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Vol. 12 No. 3 SEPTEMBER 2018

FOR THE METAL, CERAMIC AND CARBIDE INJECTION MOULDING INDUSTRIES

in this issue Design for MIM: Ten rules Arburg presents the future of PIM BASF’s Ultrafuse Published by Inovar Communications Ltd

www.pim-international.com


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• At RYER, all our feedstocks are manufactured to the highest level of quality, with excellent batch-to-batch repeatability. • RYER is the ONLY commercially available feedstock manufacturer to offer all five debind methods. • RYER offers the largest material selections of any commercially available feedstock manufacturer. • RYER offers technical support for feedstock selection, injection molding, debinding and sintering.


Publisher & editorial offices

Inovar Communications Ltd 11 Park Plaza Battlefield Enterprise Park Shrewsbury SY1 3AF, United Kingdom Tel: +44 (0)1743 211991 Fax: +44 (0)1743 469909 Email: info@inovar-communications.com www.pim-international.com Managing Director and Editor Nick Williams Tel: +44 (0)1743 211993 nick@inovar-communications.com

For the metal, ceramic and carbide injection moulding industries

Publishing Director Paul Whittaker Tel: +44 (0)1743 211992 paul@inovar-communications.com Assistant Editor Emily-Jo Hopson Tel: +44 (0)1743 211994 emily-jo@inovar-communications.com Consulting Editors Prof Randall M German Former Professor of Mechanical Engineering, San Diego State University, USA Dr Yoshiyuki Kato Kato Professional Engineer Office, Yokohama, Japan Professor Dr Frank Petzoldt Deputy Director, Fraunhofer IFAM, Bremen, Germany Dr David Whittaker DWA Consulting, Wolverhampton, UK Bernard Williams Consultant, Shrewsbury, UK Production Hugo Ribeiro, Production Manager Tel: +44 (0)1743 211991 hugo@inovar-communications.com

Advertising

Jon Craxford, Advertising Director Tel: +44 (0) 207 1939 749, Fax: +44 (0) 1743 469909 jon@inovar-communications.com Subscriptions Powder Injection Moulding International is published on a quarterly basis as either a free digital publication or via a paid print subscription. The annual print subscription charge for four issues is £145.00 including shipping. Accuracy of contents Whilst every effort has been made to ensure the accuracy of the information in this publication, the publisher accepts no responsibility for errors or omissions or for any consequences arising there from. Inovar Communications Ltd cannot be held responsible for views or claims expressed by contributors or advertisers, which are not necessarily those of the publisher. Advertisements Although all advertising material is expected to conform to ethical standards, inclusion in this publication does not constitute a guarantee or endorsement of the quality or value of such product or of the claims made by its manufacturer. Reproduction, storage and usage Single photocopies of articles may be made for personal use in accordance with national copyright laws. All rights reserved. Except as outlined above, no part of this publication may be reproduced or transmitted in any form or by any means, electronic, photocopying or otherwise, without prior permission of the publisher and copyright owner. Printed by Cambrian Printers, Aberystwyth, United Kingdom ISSN 1753-1497 (print) ISSN 2055-6667 (online) Vol. 12. No. 3 September 2018 © 2018 Inovar Communications Ltd

Design for MIM: A methodology for component development The concept of Design for Additive Manufacturing (DfAM) has quickly become established as a crucial tool in the development of metal AM applications. Thanks to DfAM, the considerations and strategies for optimising an application and maximising the opportunities presented by AM can be clearly understood and implemented. Despite being a much more mature technology, there are still relatively few designers who have a deep understanding of such a process as applied to MIM. We therefore have a situation where too many MIM parts are not designed specifically for the process, often resulting in an unnecessarily complex product development cycle and severely limiting the opportunities to take full advantage of the process. Whilst the MIM industry works hard to educate with design guidelines, perhaps there is an opportunity to replicate what has so quickly been achieved in AM and evolve a broader methodology of Design for MIM, or perhaps to borrow from AM, DfMIM. No process, AM included, offers complete ‘design freedom’, but for a high-volume manufacturing solution MIM has a remarkable potential. When AM-style tools such as topology optimisation, parts consolidation, multi-material manufacturing and simulation are applied by designers at an early stage using a structured DfMIM approach, there is the potential for a completely new generation of MIM parts to be developed. Nick Williams, Managing Director & Editor

Cover image AMT Pte, Ltd’s EPR Flow Block won an MPIF Grand Prize at POWDERMET2018 (Courtesy MPIF)

September 2018 Powder Injection Moulding International

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In this issue 61

Design for MIM: Ten rules to save time, reduce costs and improve quality

Developing a component for a new manufacturing process can be a daunting prospect. It is in any business’s nature to be cautious of change and to minimise risk; however, any successful business must also recognise when an opportunity is too good to ignore. For those who are just at the point of discovering MIM technology, Matt Bulger reveals the ten key rules for success, as observed in his nearly three decades as a developer and manufacturer of MIM components.

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The future of Powder Injection Moulding: Innovations and opportunities at Arburg’s second PIM conference

Earlier this summer industry leaders from around the world came together in Lossburg, Germany, for Arburg GmbH + Co KG’s second International PIM conference. The event had the goal of exploring the future of MIM and CIM through two days of presentations by parts manufacturers, materials suppliers, equipment producers and researchers. Dr Georg Schlieper reports for PIM International.

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Ultrafuse 316LX: BASF’s ‘Catamold® on a spool’ presents opportunities for MIM producers

BASF SE’s Catamold® feedstock is synonymous with the high volume production of components by MIM. The company has now adapted this technology for metal Additive Manufacturing via Fused Filament Fabrication (FFF). This technology

Vol. 12 No. 3 © 2018 Inovar Communications Ltd

offers MIM producers a low-investment route into metal AM, whether for prototyping or the development of entirely new applications.

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A review of the sintering behaviour of selected tool steels processed by MIM

Martin Kearns and colleagues from Sandvik Osprey review the sintering behaviour of popular tool steels such as D2 and M2, and present fresh data on a range of other tool steels, some made via both prealloy and master alloy routes. Materials investigated include AISI8620 and tool steels H11, H13, S7 and high carbon, high speed steel, T15, all sintered in nitrogen.

101 POWDERMET2018: The influence of material characteristics on the processing and properties of PIM parts A number of the papers presented during the technical sessions at POWDERMET2018 addressed issues related to achievable properties and the influence of feedstock characteristics on the processing of PIM products. This report presents a comprehensive review of selected conference papers in these categories.

Regular features 7

Industry news

113

Events guide

114

Advertisers’ index

September 2018 Powder Injection Moulding International

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Industry News

Industry News To submit news for inclusion in Powder Injection Moulding International please contact Nick Williams, nick@inovar-communications.com

OBE demonstrates weight reducing MIM with automotive valve cam follower OBE Ohnmacht & Baumgärtner GmbH & Co. KG, a manufacturer of precision mechanical metal parts headquartered in Ispringen, Germany, has developed a metal injection moulded automotive valve cam follower. According to the company, the use of MIM to produce the cam follower increases efficiency and saves weight, while also reducing translatory inertia. By using the capability of Metal Injection Moulding to create complex and lightweight shapes using highly temperature resistant alloys, OBE stated that it is possible to develop parts for the areas of automotive engines which demand the highest performance, such as components for fuel injection and combustion or valves. A valve cam follower is a key component of the valve gear, designed to improve the performance of high-speed racing engines by transforming the circular motion of the camshaft into an upward and downward motion. By designing the component

for MIM, OBE stated that it was able to improve the efficiency and economy of the production process, while reducing the part weight. OBE began MIM production in 1996 and now produces MIM components under the brand mimplus®. The company offers a range of services from product development support through to finishing and assembly of MIM components and subassemblies. In addition to its Ispringen headquarters and production plant, the company operates three subsidiaries in Italy, Hong Kong and China, and has representatives in Japan, South Korea, France and Brazil. www.obe.de

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OBE’s MIM valve cam follower, which offers reduced weight and increased efficiency (Courtesy OBE Ohnmacht & Baumgärtner GmbH & Co. KG)

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Industry News

Vibrom expands its PIM facilities with innovative technologies to meet growing demand Vibrom s.r.o, a family-run company based in Trebechovice pod Orebem, near Hradec Kralove, the Czech Republic, has expanded its manufacturing facilities to meet customer growth and increasing production volumes. The expansion was marked with a ceremonial opening on June 20, 2018, attended by eighty, including staff, customers and business partners. Following the opening, PIM International spoke to Alzbeta Bronckersova, Process Engineer at Vibrom, about the expanded facilities and the growth which is driving them. Speaking on the reasoning behind the expansion, Bronckersova stated, “Our existing customers are implementing more and more products in metal and we needed to increase our capacity. We also recognised the need to embrace the latest technologies and adapt to the recent industry trends. In particular, we see a demand for the production of much bigger parts than those that

are typically associated with MIM production.” The new facilities include an Arburg 420S Allrounder injection moulding machine with Regloplas Variotherm mould temperature controllers, a Kuka 6-axis CNC robot and a custom-built sintering furnace produced by Czech company Clasic using retort and heating elements from Plansee. Kuka’s 6-axis robot, stated Bronckersova, offers particularly interesting possibilities for the company; “It can do some post-processing on green parts during the moulding cycle. We have developed one application where it is capable of drilling six threads in one part after injection moulding.” The addition of a custom-built furnace was also critical, stated Bronckersova. “Existing customers are implementing more and more products and the volumes are getting bigger. We were in need of doubling our capacity,” she stated.

“So a furnace was developed to handle our low alloy parts, sintering just in nitrogen.” Vibrom first introduced Metal Injection Moulding into its PIM portfolio in 2012, with its first MIM production hall being opened in 2014. By 2016, the company reported that it was focused on the production of complex MIM and CIM parts with high dimensional tolerances, typically starting at volumes of around 5,000 pieces. Speaking to PIM International in June, Bronckersova looked ahead to the company’s potential development over the next five years: “We are expecting to produce parts in higher volumes, and to be producing more challenging and heavier parts,” she stated. Vibrom also sees its material offering developing in the near future. Currently, the company offers only those feedstocks available as part of the portfolios of BASF and PolyMIM, but Bronckersova stated that it aims to start producing its own feedstock from less common materials such as H13 (DIN 1.2344 tool steel) in the near future. “This is a project which we would like to start working on from the beginning of 2019,” she concluded. www.vibrom.cz

The new facilities include a custom-built sintering furnace produced by Czech company Clasic (top left) and an Arburg 420S Allrounder with Regloplas Variotherm mould temperature controllers and a Kuka 6-axis CNC robot (right)

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Powder Injection Moulding International

September 2018

© 2018 Inovar Communications Ltd

Vol. 12 No. 3


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Industry News

AP&C and Canada’s NRC develop advanced image analysis for metal powders The National Research Council of Canada (NRC) and AP&C, a GE Additive company based in Montreal, Quebec, Canada, have developed a way to test the quality of metal powders using x-ray micro-computed tomography (microCT) and 3D image analysis. According to the partners, this could lead to the production of stronger, cleaner, safer and more reliable parts for aerospace and medical devices. The testing method developed allows for the detection of very low concentrations of foreign particles in powders. Using x-ray micro-CT and 3D image analysis, each individual foreign particle is visualised and its size, brightness and overall concentration measured. In situations where cross-contamination is a concern, the technique is said to be more sensitive and discriminating than current methods available for chemical analysis. The testing method was validated using titanium powders intended to be used in aerospace parts, in collaboration with industrial partners. The NRC and AP&C are now said to be expanding its capabilities to cover other materials and metals, such as nickel alloys. In relation to Additive Manufacturing, the method could be especially useful in the qualification of recycled powders in safetycritical applications. The partners stated that they are cooperating further on improving and developing metal powder characterisation methods that are better adapted to the specific needs of industry. In addition to detecting foreign particles using x-ray micro-computed tomography, the NRC is currently working on analysing the flow of metal powders by measuring how spherical and porous particles are. Louis-Philippe Lefebvre, Powder Forming Team Lead, Medical Devices Research Centre, NRC, stated, “We hope this new method will support the industrial adoption of 3D printing and ease its implementation in highly regulated environments such as the aerospace and medical devices industries. As a leader with over thirty years of experience in Powder Metallurgy and Additive Manufacturing, the National Research Council is pleased to have joined forces with AP&C to improve the reliability of the manufacturing process and metal powder behaviour.” “The competitiveness of 3D printing relies heavily on the capability of machine users to recycle their powders; however, the industry is concerned that foreign particles will be introduced in the feedstock as the powder is recycled,” added Frederic Larouche, Executive Vice President & Chief Technology Officer, AP&C. “The method we are developing could help confirm that the feedstock maintains the utmost cleanliness during processing. Leveraging our complementary research and development competencies should help speed the development of 3D printing technologies.”

Vol. 12 No. 3 © 2018 Inovar Communications Ltd

Dr Fabrice Bernier, a researcher at the NRC, analyses powders used in Additive Manufacturing (Courtesy National Research Council of Canada) AP&C has been collaborating for more than six years with the National Research Council of Canada on developing and characterising titanium and nickel superalloy powders for AM, Metal Injection Moulding and other Powder Metallurgy processes. “Our partnership with the National Research Council, a recognised research organisation with deep expertise in Powder Metallurgy and materials characterisation, is supporting Advanced Powders & Coatings’ growth and allows us to offer betterintegrated solutions to our partners,” concluded Larouche. www.ge.com/additive/additive-manufacturing/materials/apc-homepage | www.nrc-cnrc.gc.ca

AMT Pte Ltd 3 Tuas Lane, Singapore 638612 Tel: +65-6865 5700 I Fax: +65-6863 6550 contact@amt-mat.com I www.amt-mat.com ISO 9001:2015 ISO 13485:2003

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Industry News

Metal Injection Moulding in China: 2017 part sales estimated at $788 million The 2017 China Metal Injection Moulding Industry Status Report, published by the Powder Metallurgy Branch Association of the China Steel Construction Society, provides invaluable insight into the recent development of China’s Metal Injection Moulding industry. Sales of MIM parts were reported to be in the region of CNY ¥5.4 billion ($788 million) in 2017, an increase of 10–15% compared to 2016. At present, there are said to be over 250 MIM manufacturers in China. The major driving force for growth in China’s MIM industry continues to be consumer electronics applications, with the largest application area being mobile phones (65.7%), followed by wearable devices (6.9%) and computers (4.9%). Other application areas for MIM include automotive (7.2%), hardware (6%) and medical devices (3.9%). The total shipment of materials (powders and feedstock) for MetaI Injection Moulding was reported at between 8000 and 8500 tons. The report stated that market share remains relatively equally divided between domestic (55%) and foreign (45%) producers. It was estimated in the report that around 80% of Chinese MIM firms have the capability to produce feedstock in house, although many use a combination of ready to use and self manufactured feedstocks. Of imported feedstock, BASF’s Catamold is reported to have accounted for 90% of the market. The most widely used MIM materials in China continued to be stainless steels (70%) and low alloy steel (20%), accounting for a combined 90% of production. Tungsten-based materials accounted for 8% of production, with hardmetals and copper, titanium and aluminium alloys making up the remaining 2%. It was reported that new materials R&D for MIM was focused on nickel free alloys, non-magnetic titanium and aluminium alloys. Applications for

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these materials were found mainly in the automotive and medical industries, including for renewable energy vehicles and medical implants, and in the aerospace and specialist hardware industries. The report anticipates that, with the continued involvement of investors, as well as moves by some Chinese-based MIM enterprises toward stronger integration and overseas development, the pace of

growth for the industry will quicken. Meanwhile, innovative small and medium-scale enterprises will continue to have the space to grow and develop as the industry evolves. www.cncscs.org/english/about5. asp MIM in China: Industry insight The June 2018 issue of PIM International features reports on visits two Chinese MIM producers, Shanghai Future High-tech Co., Ltd. and Shenzhen Shindy Technology Co., Ltd. Read these reports in full on our website. www.pim-international.com

MIM material consumption in China, 2017 Hardmetals, copper, titanium, aluminium alloys 2% Tungsten-based materials 8%

Stainless steels 70%

Low alloy steel 20%

Metal Injection Moulding material consumption in China, 2017

MIM applications in China, 2017 Other, 5.40% Medical devices, 3.90%

Mobile phones, 65.70%

Hardware, 6.00%

Automotive, 7.20% Computers , 4.90% Wearable devices, 6.90%

Metal Injection Moulding applications in China, 2017

Powder Injection Moulding International

September 2018

© 2018 Inovar Communications Ltd

Vol. 12 No. 3


Thermoprozessanlagen GmbH

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Industry News

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POWDERMET2018: State of the PM industry in North America 2018 The Opening General Session of the POWDERMET2018 International Conference on Powder Metallurgy and Particulate Materials, San Antonio, Texas, USA, June 17-20, included a presentation by MPIF President John Sweet, who gave delegates a detailed overview of the state of the North American Powder Metallurgy industry. Sweet stated that the PM industry as a whole gained in 2017, with metal powder shipments growing modestly. PM tooling and equipment makers reported favourable business levels, along with MIM producers. Metal powder shipments and trends Manufacturers of metal powders for conventional PM experienced favourable business levels in 2017 and reported a positive outlook for 2018. Most powder shipments in North America increased. Companies are continuing to add new and improved products to strengthen the industry’s technology edge and Sweet stated that some of these new products include gas atomised alloys for AM, machinabilityenhanced powders, magnetic materials and premixes with reduced levels of nickel. It was reported that metal powder shipments in Europe last year were stable, whilst PM markets in Asia experienced modest growth, with China in the lead. Sweet stated that, according to most industry observers, the US market for traditional PM grade powders has stabilised. With existing technology and applications, annual near-term growth will be modest, ranging in the lower single digits. Without the introduction of new high-volume PM ‘champion’ parts, the industry will ease into a maturing mode. Nevertheless, MIM-grade powder shipments will see higher growth figures along with similar powders for AM applications. While demand for PM parts from the automotive industry will remain fairly stable overall in 2018, markets such as lawn and garden, agricultural, commercial, off-road and products connected to home building are gaining. In the annual PM Industry Pulse Survey conducted by the MPIF, 78% of the Metal Powder Producers Association (MPPA) members who responded plan on increasing capital spending this year. MPPA members rank the three most significant business challenges they face as: expanding PM applications, an aging workforce and the impact of the ‘new’ automotive industry. Manufacturing challenges include expanding capacity, developing new materials and continuous improvement. Most companies are operating above 80% of rated capacity.

Industry News

Equipment trends PM equipment suppliers, including suppliers of tooling, compacting presses and sintering furnaces, enjoyed a healthy 2017, according to Sweet, and sales are expected to increase again in 2018. Equipment builders and tool makers face the same scarcity of skilled employees as their customers and one company expects a drop in production this year due to the difficulty in replacing its experienced retiring employees. Strong trends include more precise tolerances in tooling, more automation and data collection in equipment operation. Metal Injection Moulding trends highlighted Members of the Metal Injection Molding Association (MIMA) reported a positive outlook for 2018. The US MIM parts market in 2017 increased up to 5% to an estimated range of $367–$420 million. The industry still includes about 25–30 commercial job shops and 15–18 captive parts operations making dental/medical and firearms parts for their own products. The top seven MIM job shops account for more than 50% of the commercial market, stated Sweet. It is estimated that MIM-grade powders consumed in the US (domestically produced and imports) in 2017 increased by about 5% to an estimated range of 1,430 mt (1,577 st) to 1,829 mt (2,016 st). However, some estimate a much larger market at about 3,175 mt (3,500 st).

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Industry News

Automation and process control of the MIM manufacturing process is a continuing trend. MIM parts makers are eliminating waste and handling for quicker processing flow. Narrowing the design cycle of new MIM parts with 3D modelling and mould simulation is another trend. The MPIF Pulse Survey reported the following principal MIM market mix, according to weight of parts shipped. In contrast, the number of parts shipped changes the mix somewhat. The firearms and medical sectors still account for more than 50% of the total MIM market, a trend recorded for at least the past five years. On the heels of a peak year in 2016, US firearms manufacturers faced reduced sales in 2017, impacting MIM parts suppliers that are adjusting to a new norm. Depending upon the national political situation and calls for more stringent national gun controls, the firearms market will stabilise to a more normal supply-anddemand model. Technology trends The MPIF Technical Board continues to encourage and generate programs to advance PM technology. For 2018, the Technical Board developed the special interest program ‘Energy Generation & Storage Technologies’, an outgrowth from the PM Technology Scan—2017

Future perspective Sweet concluded by stating that opportunities within PM are substantial and that the industry will continue innovating with new processes and products. 98% of the MPIF members that responded to the 2018 PM Pulse Survey believe sales will remain the same or increase in 2018. “All six of the federated trade associations report a lack of skilled employees and are concerned with an aging workforce. The PM industry needs to address this shortage of employees to support growing sales. NSF and the CPMT/Axel Madsen grants put young engineers into the pipeline. Now it is up to us to attract and retain these young engineers, a key to our industry’s continued success,” stated Sweet. Without a doubt, PM will persist for many years as an important manufacturing process and technology. The industry has a rich history of creative and resourceful PM practitioners overcoming marketplace challenges, reinventing itself by adopting new technologies and entering new markets. In the end, Sweet was confident that PM remains a unique industry with a bright future, prepared to meet and conquer all obstacles. www.mpif.org

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‘Review of Battery Technology for Potential Future PM Applications’. In addition, the board developed the PM Technology Scan—2018 ‘Machinery Sensors & Information Technology’, stressing that the ability to control processes is directly related to monitoring the variables driving the process. Sweet explained that the MPIF Technical Board and the Center for Powder Metallurgy Technology (CPMT) continue to collaborate to advance PM through outreach activities. For example, the National Science Foundation (NSF) and the annual CPMT/Axel Madsen Conference Grants provide funding for university students to attend POWDERMET2018 and AMPM2018. Students are provided the opportunity to engage with other university students, exchange activities at their universities and are paired with Tech Board mentors to guide them through the conference and receive feedback from the students. CPMT has provided over $140,000 in conference grants to 109 students since 1990, with an estimated 25% of the recipients remaining connected to the PM industry. Additionally, CPMT scholarship awards, which are separate from the grant program, have surpassed $500,000, awarded to nearly 150 students since 2000.

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September 2018

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Vol. 12 No. 3


VISIT US AT

BOOTH 59

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Industry News

PSI moves towards continuous atomisation with its largest capacity vacuum inert gas atomiser to date

• Low weight • Good mechanical stability • Low heat capacity • high open porosity • dust- and particle-free surface • homogeneous shrinkage • Absorbtion of the binder into the pores during the debindering process • Very smooth surface finish • Compatibility to Molybdenum, CFC, RSiC • Good to very good thermal shock resistance • Handling and assembly with robots possible

Al2O3 ZrO2 LTCC Dentalceramics

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Phoenix Scientific Industries Ltd (PSI), Hailsham, UK, recently installed its largest capacity vacuum inert gas atomiser (VIGA) to date at a UK-based metal powder supplier. Equipped with a 500 kg capacity furnace, and having the option to add a second as production requirements increase, the system is designed to produce high-quality metal powders that are suitable for the MIM, Additive Manufacturing and HIP industries (Fig. 1). The design for the VIGA installed by PSI features two induction furnaces that are diametrically opposed and pour alternately into a central tundish, which is also heated by induction, under which sits the atomisation die (Fig. 2). PSI stated that the die is the crucial component in the system and its performance is key to the production rate of in-size powder. The company stated that with this atomiser design a tonne of powder can be produced in one production cycle with evacuation and gas backfill being performed on both furnaces and melting rates being adjusted so that when one furnace is emptied, the second is available, enabling atomisation to continue without pause. “Those considering atomising system configurations might ask, ‘Why not have a single furnace of one tonne and avoid any complications that two

Fig. 1 The new one tonne VIGA system 500 kg furnaces might confer?’” stated Bill Hopkins, Managing Director of PSI. “The answer is that big is not always better.” Hopkins explained that, with the induction furnaces used for atomisation, the pour rate is relatively slow compared to other operations such as casting. This means large melts being held at temperature for long periods with the associated problems of refractory wear, slag and high inclusion counts – all deleterious to the quality of nickel or steel PM components used in high-performance applications.

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Fig. 2 Schematic of the dual-furnace tilt and pour system designed for the new atomiser installed by PSI

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In addition, temperature control of melt from a large induction furnace, kept at high angles of tilt for prolonged periods, is not straightforward. Faster pour rates and therefore atomisation rates of the melt, due to geometric fluid and heat flow considerations at the atomisation die, lead to higher temperatures in the near vicinity of the atomisation spray plume, with negative consequences for in-size powder yields and morphology. Faster pour rates also imply correspondingly high atomising gas flow rates to achieve the desired median size in the as-atomised powder. The gas supply system, including pumped cryogenic supplies, is a significant capital and operating cost for a production atomiser. Further, a tilting induction furnace occupies a significant vertical distance that must be accommodated within the diameter of the requisite cylindrical vacuum chamber, leading to disproportionate capital cost as,

for a given volume, larger-diameter chambers are much more expensive than smaller diameter, longer chambers housing two smaller furnaces. Additionally, a large melt which is not poured for any reason will take much longer to cool down and restart for the next process cycle than a small one. Air melting furnaces supplying atomisation systems can readily be supplied with ‘bale out’ facilities to empty a furnace and thus save the refractory lining, but this is expensive to arrange and cumbersome to operate within a vacuum chamber. Hopkins concluded that, in a batch process involving metal refining operations prior to the atomisation stage of the process, productivity of good quality powder is not necessarily increased by increasing furnace size. There appears to be an optimum size around the 500 kg level where the capital expenditure and operation expenditure costs, which form part of a metal powder cost, are minimised.

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Fig. 3 IN718 nickel alloy powder produced by a PSI VIGA

To optimise yields of powders for MIM, the use of atomising gas heated to 500°C to increase the yield of sub 20 µm powder to the extent that the capital investment in plant to both heat the gas and later dissipate the significant increase in thermal energy, is well-justified. Generally, a reduction of 5 µm to the d50 value of as-atomised powder is obtained compared to room temperature atomising gas. For AM, where the desired ‘cut’ lies in the ranges 15–45 µm or 15–60 µm,

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atomisation parameters can be set to optimise the yield of in-size powder without the use of hot gas, and similarly for HIP. In addition, the use of lower metal pouring rates to reduce the standard deviation or ‘spread’ of the size distribution will generally increase the rate of in-size powder production and give a better product, although reducing the rate of as-atomised powder production. Hopkins stated that, in a batch VIGA, the time spent actually atomising is a relatively small fraction of the total cycle time, which includes loading, evacuating, melting, melt conditioning (composition trimming) and cooling. As a result, to pour and atomise faster than is optimal for maximising in-size yield and quality is often counterproductive, as only a little time is saved. However, even when batch atomisation is optimised for yield and quality, the productivity of a high-value batch VIGA is still very low in terms of capital utilisation. “In the same way that strand casting of low carbon steels

displaced ingot casting in the last century, now is the time to introduce the same approach to vacuum inert gas atomisation of steels and nickel superalloys and enjoy the same capital expenditure and operating cost benefits which this approach brings to lowering powder cost,” Hopkins stated. With air-melting furnaces, the approach is relatively simple from an engineering standpoint. Alternately pouring furnaces are arranged to feed a central tundish (Fig. 2). As long as the non-pouring furnace can be recharged and is able to produce melt faster than the alternate furnace’s contents can be atomised, then the process will continue until the pouring and feeding refractories become worn or blocked and the process is halted to replace them. For premium quality powders, where the slag and inclusions associated with air melting are unacceptable, the challenge is to keep the atomising tundish constantly ‘topped up’ with metal which has been de-slagged,

vacuum refined for oxygen and carbon control and compositionally controlled to close tolerances. PSI reports that it is currently working with a major steel maker to interface the best and lowest cost bulk steel production techniques and deliver this molten feedstock to PSI twin-furnace atomisers for further refining actions before alternately pouring and atomising on a continuous basis. Here, the challenges are similar to those faced in the early days of continuous steel casting, e.g. control of pouring rates and development of pouring refractories to ensure the highest atomiser utilisation and lowest downtime. The company anticipates that this development will raise VIGA productivity from the 20–30% typically encountered in systems around the world, to more than 80%. This will allow a step change reduction in powder cost for MIM and AM applications and in turn promote the further growth of these industry sectors. www.psiltd.co.uk

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EPMA reports success of its 2018 Powder Metallurgy Summer School The European Powder Metallurgy Association (EPMA) held its eighteenth Powder Metallurgy Summer School in Vienna, Austria, July 2-6, 2018, at TU Wien. The five-day programme was hosted and coordinated by Dr Christian Gierl-Mayer, TU Wien, Austria, and Dr Marco ActisGrande, Politecnico di Torino, Italy. The programme was delivered by a range of specialists from both industry and academia, whose expertise reflect many key topics currently being employed in today’s Powder Metallurgy industry. The course began with an introduction to materials science followed by an introduction to Power Metallurgy. Presentations were then given on metal powder manufacturing, shaping technologies, sintering and post sintering operations. The properties of PM parts were discussed, along with an overview of Metal Injection Moulding and Additive Manufacturing processes. Modelling and a presentation reviewing phase diagrams were followed by a full day of practical work, where Dr Bob Moon and Dr Brian James discussed a number of case studies, organised group problem solving sessions and conducted hands-on lab work. The last two days included presentations on furnace technologies, hardmetals, light metals and magnets, as well as a detailed look at low alloy steels, special steels and high temperature materials. There was also a tour to Lithoz. The EPMA Summer Schools are particularly designed for young graduate designers, engineers and scientists drawn from a wide range of disciplines such as materials science, design, engineering, manufacturing or metallurgy. The course is open to graduates, preferably under the age of 35, who have received their degrees from a European university. The EPMA reported that a total of 60 delegates attended this year’s Summer School. Powder Injection Moulding International was a media partner for the event and participants received copies of the latest magazine, as well as copies of Metal Additive Manufacturing and Powder Metallurgy Review magazines. www.summerschool.epma.com

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Leading MIM furnace manufacturer reports strong demand from the AM sector, opens new German facility Leading Metal Injection Moulding furnace manufacturer Elnik Systems LLC, Cedar Grove, New Jersey, USA, is reporting strong sales growth to the metal Additive Manufacturing industry. The company specialises in laboratory and production scale vacuum debinding and sintering furnaces that have been specifically developed for the processing of MIM parts. As such, its systems are well suited to the thermal processing of parts produced using the new generation of MIM-like processes. The company told PIM International magazine that it has now supplied nine systems to the metal AM industry, with usable volumes ranging from 27 to 117 litres. Stefan Joens, Vice President of Elnik Systems, commented,

“There are multiple reasons for our success in the metal binder jetting and filament-based AM sector. The most important is the ability for potential customers to experiment with the furnaces at our on-site development partner, DSH Technologies, LLC.” “This service has helped part makers to understand the quality of our furnace systems, the consistent results that can be achieved and their flexibility of use before committing to a purchase. Our reputation in the debinding and sintering industry is also a strong attraction – we have demonstrated our value to the MIM industry over several decades, and now the metal AM industry is doing its homework before investing.”

Toll services expanded Elnik Systems and DSH have for many years offered toll debinding and sintering services from the New Jersey facility, enabling companies to process small-to-medium volumes of MIM and MIM-like AM parts before investing in their own furnaces, or as part of a component development programme. This service is now also being offered to the European market from a new facility in Waldachtal, Germany. Elnik Systems GmbH has the capability of processing first stage debinding via the catalytic process and second stage debinding and sintering services in an Elnik MIM3045 furnace. This large furnace has a 117 litre usable volume, is high vacuum capable, features argon purification, allows survey thermocouples to be used as needed and can process any binder-containing metal powder part, be it from a binder jetting, filament-based or pellet-based metal AM process. www.elnik.com | www.dshtech.com

MIM2019: Metal Injection Moulding Conference issues call for presentations An official call for presentations has been announced for MIM2019: International Conference on Injection Molding of Metals, Ceramics and Carbides, to be held in Orlando, Florida, USA, February 25-27, 2019. Presentation submissions will close on September 28, 2018. The conference is sponsored by the Metal Injection Molding Association, a trade association of the Metal Powder Industries Federation and its affiliate APMI International. Authors wishing to present a paper at MIM2019 should submit an abstract using the submission form, which can be downloaded via the conference website. All accepted abstracts will require a PowerPoint presentation to be submitted for review prior to the conference. Presentations are invited on the topic of innovations in: • PIM part design • PIM tooling • Moulding • Debinding • Sintering

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MIM2019 will be held at the Hilton Orlando Lake Buena Vista, Orlando, Florida, USA (Photo courtesy Carlo Pelagalli) • Metals & alloys for MIM • Ceramic Injection Moulding • PIM of hard materials As well as featuring international conference presentations, a tabletop exhibition will showcase leading materials and technology suppliers from around the world. www.mim2019.org

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Carbolite Gero’s MIM and AM seminar addresses challenges of heat treatment On July 13, 2018, furnace specialist Carbolite Gero organised a one-day seminar on Metal Injection Moulding in Neuhausen, Germany. The seminar was targeted at component manufacturers with experience in MIM and Additive Manufacturing (AM) who have an interest in new processing opportunities. The organisers stated that a combination of technical presentations on the subject of MIM and AM, plus additional presentations from various interdisciplinary manufacturing areas, provided participants with new ideas for process optimisation. Both MIM and AM are growing markets with excellent future prospects and Carbolite Gero stated that both manufacturing processes have a clearly interdisciplinary orientation, ranging from powder production through preparation and shaping to post-treatment. As such, the seminar

successfully contributed to promoting interdisciplinary exchange in this field. Prof. Dr. Carlo Burkhardt, Director of the Institute for Strategic Technology and Precious Metals at Pforzheim University, Germany, reviewed the MIM and AM processes and outlined existing challenges in these areas. Gerhard Raatz, Retsch Technology, Haan, Germany, considered the possibilities of particle size and shape analysis of metal powders using Dynamic Image Analysis. In a presentation on chemical analysis, Mike Lucka explained how to determine the carbon content in finished MIM parts with analysers from Eltra GmbH, Haan. Elisa Götze, from Karlsruhe Institute of Technology (KIT), then offered insight into research activities in the field of ceramic AM at the wbk Institute for Production Technology.

For debinding and sintering processes, Carbolite Gero believes that it is essential to create optimum gas paths to ensure uniform temperature distribution. It is for this reason that simulations have to be performed ‘to make the invisible visible’ and improve on details which cannot be seen. Carbolite Gero has therefore worked in close cooperation with the University of Pforzheim and Merkle & Partner GbR, Heidenheim, Germany, to improve debinding and sintering furnaces through computer simulations. The basics and potential of simulations were presented by Nelson Brito, University of Pforzheim, and Dr Christian Mielke, Merkle & Partner GbR. Finally, Carbolite Gero introduced its entire product portfolio for PIM and Additive Manufacturing. This includes facilities for catalytic (EBO) and thermal (GLO) debinding, metallic furnaces for debinding and sintering up to 1450°C (PDS, HTK) and facilities for stress relief heat treatment up to 800°C (GPCMA). www.carbolite-gero.com

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PSI Ltd - Hailsham - UK Tel: +44 (0)1323 449001 - info@psiltd.co.uk

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Industry News

AP&C acquires gas atomisation equipment from Avio Aero

well-suited to powder recycling for those customers seeking sustainable solutions. “Without ongoing materials GE Additive’s materials division, such as Titanium Aluminideleaderscience research and innovation, CM Furnaces,powders long recognized as an industrial in performance-proven, high AP&C, Montreal, Canada, has (TiAl), is being transferred to AP&C’s additive will struggle to advance. temperature fully continuous sintering furnaces for MIM, CIM and traditional press So, acquired the gas atomiser facility in Montreal. while thisproductivity relocation makes and sinter now OFFERS YOU A CHOICE, for maximum and sense equipment currently installed at GE The move is intended to better commercially, it is also a key element elimination of costly down time. Aviation business Avio Aero’s plant position the Additive Manufacturing of our future materials development in Cameri, Italy. This technology technologies available within the strategy.Rapid HavingTemp this complementary Choose one of our exclusive BATCH hydrogen atmosphere furnaces. is said to be complementaryDesigned to GE family, allowing both companies technology in the AP&C portfolio for both debinding and sintering, these new furnaces assure economical, AP&C’s proprietary Advanced to better focus on their respective opens up wider possibilities for simple and efficient operation. Plasma Atomisation (APATM) businesses – AP&C on materials and us as a business and also for our process. powder production high and Avio Aero on sintering customers, who with continue to want OR... choose our continuous temperature furnaces complete As the MIM and AM industry additively manufacturing aero engine to push boundaries,” stated Alain automation and low hydrogen consumption. continues to experience dramatic components, using Arcam’s EBM Dupont, President & CEO, AP&C. growth, so does the demand for CONTACT technology andmore powders developedon byour fullGiacomo US for information line of furnaces with your Vessia, Cameri plant powder and materials – with AP&C.choice of size, automation, atmosphere leader, capabilities Avio Aero, commented, “The and titanium and nickel-based alloys for The equipment is expected to up to 3100˚F equipment moving to Canada means temperature ranges / 1700˚C. the aerospace industry especially in be operational by March 2019. As a more volume and capabilities at our demand. In anticipation of further result, AP&C will become a preferred Cameri plant. And of course more increasing demand over the coming supplier of TiAl for GE Aviation, as 3D printing machines. In addition years and following a strategic well as extending its technology to focusing on additive processes, E-Mail:business review, the gas atomiser portfolio and ability to offer a wider we will also have the time and more info@cmfurnaces.com technology installed in 2014 at Avio range of possibilities to its customers space to train and equip our existing Web Site: 103 Bloomfield, NJ 07003-4237 Aero’s Cameri facility, originally through an extended choice of Dewey Street and new team members with future Tel: 973-338-6500 Fax: 973-338-1625 http://www.cmfurnaces.com it was intended for the in-house powder processes. Gas atomisation manufacturing skills.” production of special metal alloy technology is said to be particularly www.ge.com/additive

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Ex-GE Chairman & CEO joins Desktop Metal’s Board of Directors

APMA2019 to be held in Pune, India, and Call for Papers issued

Jeffrey Immelt, former Chairman and CEO of General Electric, has been elected to the Board of Directors of Desktop Metal, Burlington, Massachusetts, USA. Immelt brings with him more than forty years of technology and business experience and said of his election to the board, “I am excited and honoured to join the Desktop Metal board and work with this exceptional team of visionary entrepreneurs.” Ric Fulop, Desktop Metal’s Founder and CEO, stated, “On behalf of Desktop Metal’s directors and entire team, it’s an honour to welcome Jeff to our board. In addition to his experience leading one of the largest and most admired companies in the world, Jeff is a respected executive with a passion for technology and innovation. His track record for driving creativity and on a global scale makes him a valuable addition to the board as we continue to drive Desktop Metal’s innovation and growth strategy.” Founded in 2015, Desktop Metal offers two metal Additive Manufacturing systems – the Studio System™ for rapid prototyping and the Production System™ for series production of metal AM parts at scale. Using its proprietary Single Pass Jetting (SPJ) technology, the Production System is said to be 100 x faster than currently available laser-based AM systems. “Since it was founded nearly three years ago, Desktop Metal has become a trailblazer across the Additive Manufacturing landscape and I have a tremendous respect for the company’s ability to innovate,” Immelt added. “I look forward to sharing my experiences and contributing to the future direction and growth of this emerging metal 3D printing pioneer.” www.desktopmetal.com

The 5th International Conference on Powder Metallurgy in Asia (APMA 2019) will be held at the JW Marriot Hotel in Pune, India, from February 18–21, 2019. The event will be hosted by the Powder Metallurgy Association of India (PMAI).

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APMA 2019 will be India’s largest ever conference on Powder Metallurgy and particulate materials, and is expected to attract over 500 delegates. The conference will showcase the capabilities of the PM industry through technical papers offering updates on research, industry developments and trends across the PM supply chain. A call for papers has been issued and abstract submissions will close on September 30, 2018. www.apma2019.com

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Industry News

Leading ceramic Additive Manufacturing event to be held in Vienna AM Ceramics 2018, a key event for the Additive Manufacturing of high-performance ceramics, is scheduled to take place at Fleming’s Conference Hotel in Vienna, Austria, from October 9–10, 2018. Organised by DKG (the German Ceramic Society) in cooperation with Lithoz, Cluster Werkstoff Keramik, 3Druck.com, Ceramic Applications and the CFI, the conference will give attendees the opportunity to connect with global AM companies and research institutes for a discussion of AM for high-performance ceramics. Key topics addressed during the conference programme will be: • State-of-the-art ceramic Additive Manufacturing technologies and material use • Design rules and process management for ceramic Additive Manufacturing • Potential and challenges of ceramic AM for various industries • Best practice examples, opportunities and feasibility studies

Additively manufactured ceramic components (Courtesy Lithoz) • Upcoming trends in AM beyond prototyping A number of presentations will be featured across the two-day event, with speakers from companies and organisations including Lithoz GmbH (Austria), the Manufacturing Technology Centre – MTC (UK), Imerys Technology Center Austria GmbH, Alumina Systems GmbH (Germany), Ceramco Inc. (USA) and more. Last year, AM Ceramics 2017 attracted more than eighty participants from the ceramic sector. Registration for the 2018 event is now open and includes attendance to all sessions on the conference programme. www.am-ceramics.dkg.de

Carbolite Gero offers updated retort furnace Carbolite Gero has launched an updated GPCMA/174 retort furnace which it states is suitable for a variety of laboratory, pilotscale and industrial applications requiring heat treatment to 1150°C. The completely revised 174 litre furnace reportedly reduces O2 levels to below 30 ppm and offers uniform The GPCMA/174 temperature distribution and gas retort furnace tightness. Continuous monitoring of inert gas flow volumes and forced cooling for faster cycle times are further features said to ensure safe and efficient operation. Designed with a modified inert atmosphere for annealing and sintering of parts, the furnace can be fitted for compliance to AMS 2750E Class 1 (+/-3°C) and be equipped with instrumentation type A, B, C or D. The GPCMA/174 features cascade control for loadtemperature sensing, as well as a swing door design for ease of loading and unloading, and is said to be ideal for applications which call for a single platform furnace and small volume requirements for one-off components. www.carbolite-gero.com

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Industry News

Fraunhofer IFAM celebrates its 50th anniversary in Bremen On June 13, 2018, the Fraunhofer Institute for Manufacturing Technology and Advanced Materials (IFAM) celebrated its 50th anniversary with a formal reception held by the mayor of the Free Hanseatic City of Bremen, followed by a dinner attended by more than 350 employees and invited guests from industry, politics and science. The Workgroup for Applied Materials Research (AFAM) was founded in 1968 by Prof Dr Ing habil Alexander Matting of the Technical University of Hannover, Germany. Located in the north of Bremen and vested with a budget of less than 1 million Deutsche Mark, the original focus of the workgroup and its twenty-five

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Staff gather as part of the 50th anniversary celelebrations at IFAM in Bremen initial researchers and technicians was on welding technology and the impact of the welding process on joined materials. In 1970, the workgroup was integrated into the Fraunhofer Gesellschaft, and established in 1974 as a Fraunhofer Institute, updating its

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title accordingly to Fraunhofer IFAM. Over the course of the 1970s and 80s, the group’s research focus expanded towards manufacturing technology, surface technology and material behaviour. Its researchers began to explore bonding as an alternative joining method and the first training

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courses and lectures on adhesive bonding were held. An early venture into powder technology involved some successful experiments on the sintering of tungsten heavy metal alloys. In 1992, the Dresden Branch laboratory for Powder Metallurgy and composite materials was integrated into the institute, bringing with it thirty-five researchers and technicians and further enhancing its powder technological competence and research experience. The technical centre for Metal Injection Moulding was also established during the early 1990s. Powder technology has since played an important role in Fraunhofer IFAM’s R&D activities. In the present day, the institute’s researchers and technicians have a deep and comprehensive knowledge of the entire powder metallurgical production process from powder to component. R&D solutions are implemented at the institute’s

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facilities using state-of-the-art industrial-scale equipment. Since the mid-90s, Fraunhofer IFAM has also been focused on the area of metal Additive Manufacturing. Among the most recent of the institute’s achievements in metal AM is its development of a process which uses Fused Filament Fabrication (FFF) to manufacture metal parts, announced in October 2017. Today, Fraunhofer IFAM is one of Europe’s largest research institutes in the fields of powder technology, casting technology, surface technology and bonding. It has an annual budget exceeding €42 million and its primary business areas are the automotive, aviation, energy and environment, medical technologies and life sciences, and maritime industries. It currently employs more than 660 staff at five locations in Germany and has registered a total of 1,172 patents and published more than 5,000 scientific papers to date. www.ifam.fraunhofer.de

Hagen Symposium 2018 programme published The 37th Hagen Symposium on Powder Metallurgy, organised by the Fachverband Pulvermetallurgie (FPM), will take place in Hagen, Germany, November 29-30, 2018. The German-language event will include presentations on a wide range of PM technologies, as well as discussions on how a digitised industry 4.0 will impact the Powder Metallurgy sector. It has been announced that the recipient of this year’s Skaupy Award, to be presented during the symposium, is Dr Ing Thomas Weissgärber, Fraunhofer IFAM, Dresden. In his opening Skaupy lecture, Dr Weissgärber will discuss the production of Powder Metallurgy composites with functional properties. www.pulvermetallurgie.com

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Industry News

Tosoh to increase zirconia powder production capacity to meet demand for dental and decorative applications

Air Products to relocate its global headquarters

Japan’s Tosoh Corporation has announced its decision to increase its production capacity for zirconia powder, an advanced ceramic product the company manufactures at its Nanyo Complex in Shunan City, Yamaguchi Prefecture. Tosoh’s high-strength, hightoughness yttria-stabilised zirconia powder has, states the company, earned a dominant share of the global market through its quality and stability. Applications for the powder include components such as connectors for fibre optic systems and grinding media for raw materials used in the electronics industry. In recent years, Tosoh developed a product lineup (Zpex®, Zpex Smile, Zpex4) of zirconia powders that features varying grades of translucency to meet

Air Products, Allentown, Pennsylvania, USA, has announced that it will begin construction on its new global headquarters in Lehigh Valley, Pennsylvania, close to its existing location. The new headquarters will be based on a fifty acre site and the company expects to break ground in March 2019, with completion targeted for Summer 2021. The new headquarters will be occupied by approximately two thousand employees. As it continues to focus strongly on Industrial Gases, Air Products has divested a number of non-core businesses over the last two years. These moves, in combination with other operational changes, are said to have resulted in excess building space at Air Products’ present location. www.airproducts.com

the increasing demand for use in dental applications. The company has also created a variety of colour grades for decorative and fashion applications and has rolled these products out worldwide. Zirconia powder is one of the main products of Tosoh’s Advanced Materials Division and the company aims to further expand the scale of business and strengthen profitability by responding to rapidly increasing demand. The company will invest a total of ¥5 billion in expanding the facility, resulting in an increase of 30% over current production capacity. Construction was scheduled to start in August 2018 with completion in June 2019. Commercial operations are slated to begin in October 2019. www.tosoh.com

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Industry News

Sandvik reports record-high orders and revenues in its second quarter 2018

GET INSIGHT INTO YOUR POWDERED METAL MATERIALS COMPLEMENTARY ANALYTICAL TOOLS FOR POWDER METALLURGY AND ADDITIVE MANUFACTURING • Automated imaging for assessing the shape and roughness of metal powders • Laser diffraction for measuring the particle size distribution of metal powders • Gel permeation chromatography for determining the molecular weight and structure of polymeric binders and waxes

• X-ray fluorescence for elemental identification and quantification • Rheology for evaluating flow behavior of injection molding feedstocks and binders • X-ray diffraction for determining crystal structure, stress, and phase analysis of metals and alloys

www.malvernpanalytical.com/powder-metallurgy

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Sandvik AB, headquartered in Stockholm, Sweden, has reported record results for the second quarter of 2018. In the period, both order intake and revenues were said to have increased by 12% year-on-year, and strong positive development was reported in all three business areas. Björn Rosengren, President and CEO of Sandvik, stated, ”On the back of increased demand in all three major geographical regions stemming from positive development in all customer segments, we reported record-high orders and revenues for the second quarter of 2018. The high activity level in combination with a sustained focus on efficiency resulted in both adjusted operating profit and the operating margin of 19.4%, reaching all-time-high levels.” Adjusted operating profit was said to have risen by 36% year-on-year to SEK 5,067 million (Q2 2017: 3,718 million), which Sandvik stated was supported primarily by strong organic growth. Across the Sandvik Group, orders increased significantly in all three major global regions, with Asia showing 17% growth, Europe 16% and North America 8%. Underlying customer activity was said to be high in all customer segments and regions. Sandvik Materials Technology, which includes the Osprey metal powders business, reported an adjusted operating profit of SEK 558 million (Q2 2017: 189 million) and a 17% increase in order intake including the impact of large orders. Excluding the impact of these large orders, order growth amounted to 37%. Revenues grew organically by 8%, with higher alloy prices supporting both order intake and revenues by 4%, primarily related to nickel. Sandvik Materials Technology also saw a positive impact on its Q2 operating profit of + SEK 72 million from changes to currency exchange rates and + SEK 201 million from changes to metal prices. This helped to offset a capital loss of SEK 24 million sustained due to the company’s exit from the Fagersta Stainless joint venture. For the first six months 2018, demand for Sandvik’s products was said to have improved year-on-year, with order intake noting organic growth of 9% compared to the first six months 2017. Excluding the impact from large orders, the growth amounted to 11%. Revenues increased by 13%, thought to be attributable to a broadbased improvement in customer activity in all business areas and in most customer segments. Demand for Sandvik’s products improved or remained stable in all regions. The six month operating profit was SEK 9,314 million (2017: 6,763 million) and the operating margin was 18.7% (2017: 14.9%), negatively impacted in the amount of – SEK 110 million due to changed exchange rates. Changed metal prices had a positive impact of SEK 302 million (2017: 75 million). www.home.sandvik.com

Powder Injection Moulding International22/06/2018 September 2018 15:20:42

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Industry News

Wittmann Battenfeld celebrates 10th anniversary with more than 1,400 visitors Wittmann Battenfeld celebrated its tenth anniversary with an event at its Kottingbrunn facility, Austria, from June 13-14 2018, that was attended by more than 1,400 guests. Ten years ago, Battenfeld Kunststofftechnik GmbH was integrated into the Wittmann Group and, over the course of the last ten years, the company’s entire product portfolio has been renewed and the capacity at the Kottingbrunn facility substantially expanded over several construction phases. Novel applications and the latest process technologies were demonstrated on fourteen machines from the company’s PowerSeries, among them the new vertical VPower, which was shown for the first time. The presentation of Wittmann 4.0, the company’s answer to Industry

4.0, was also highlighted. In addition to the integration of robots and peripherals on a large number of machines, the entire range of connected appliances was presented in a separate Wittmann 4.0 cell. The event opened with presentations on the company’s history, with a focus on the last ten years. In a keynote speech, Prof Dr Johannes Schilp from Augsburg University then spoke about cyber-physical production systems and explained how they could be implemented in practice. During guided company tours in the afternoon, visitors were able to view both the exhibits and the production facilities in Kottingbrunn, which have been extended by 2,200 m², including a new processing line for larger machines in the SmartPower and EcoPower series. Several ‘expert

Guests at Wittmann Battenfeld’s celebrations in Kottingbrunn corners’ dealt with topics such as process technology, integration and plasticising systems, where short presentations were offered to enable guests to gain insights into the latest technologies and processes from Wittmann Battenfeld. Georg Tinschert, Managing Director of Wittmann Battenfeld, stated, “These last ten years were successful years for our company. We are glad that so many of our customers and partners were here to celebrate with us.” www.wittmann-group.com

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Industry News

Micromeritics Instrument Corp acquires Freeman Technology Micromeritics Instrument Corporation, Norcross, Georgia, USA, a manufacturer of products for advanced materials characterisation, has announced its acquisition of Freeman Technology, Tewkesbury, UK. Freeman specialises in providing instruments for the measurement of powder flow and other behavioural properties to maximise process and

product understanding, accelerate R&D toward formulation and commercialisation and optimise powder processes. “The acquisition of Freeman Technology is very strategic to the growth of Micromeritics,” commented Preston Hendrix, President of Micromeritics. “Not only does it expand our portfolio of products and

PM Tooling System The EROWA PM Tooling System is the standard interface of the press tools between the toolshop and the powder press machine. Its unrivalled resetting time also enables you to produce small series profitably. www.erowa.com

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Powder Injection Moulding International

solutions in high-growth market segments where we are already active and have a large, global base of customers, but Freeman Technology’s strong scientific and applications focus is very much in line with the pre- and post-sales support customers have come to expect from Micromeritics.” Tim Freeman, Managing Director of Freeman Technology stated, “We are excited about joining forces with and becoming a Micromeritics company, as they have penetration in complementary segments, global market coverage and the infrastructure to help us to accelerate the growth we have established in our business since 1995.” Micromeritics offerings include techniques for characterisation of the density/volume, surface area and porosity, physical and chemical absorption, size and shape of particles, porous materials and powders. In addition to designing, building and selling its own instrumentation, Micromeritics also offers complimentary OEM and private label instruments under its Particulate Systems brand, through the Micromeritics global sales channel and distributor partners. The company also operates testing, certification and methods development laboratories under the Particle Testing Authority and PoroTechnology brands in Asia, the Americas and Europe. www.micromeritics.com www.freemantech.co.uk

September 2018

Submitting news to PIM International is free of charge and reaches a global audience. For more information contact Nick Williams: nick@inovar-communications.com

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Industry News

Euro PM2018 Congress & Exhibition attracts record number of abstracts The European Powder Metallurgy Association (EPMA) states that it has received a record number of abstracts for its Euro PM2018 Congress & Exhibition, set to take place in Bilbao, Spain, October 14-18, 2018. According to the association, over three hundred abstracts have been submitted, representing an increase of over 30% compared to Euro PM2017. The result will reportedly be one of the most extensive Euro PM Technical Programmes in the conference’s history. The Euro PM2018 Technical Programme will aim to showcase how the fields of Powder Metallurgy – from conventional press and sinter to metal Additive Manufacturing, hard materials and diamond tools, Hot Isostatic Pressing, and Metal Injection Moulding, can create unique advantages for industrial designers and engineers.

This year’s event will be held in the Bilbao Exhibition Centre (BEC), with technical sessions taking place in the BEC Tower, one of the tallest buildings in Bilbao. Running parallel to the technical programme, the Euro PM Exhibition will represent all areas of the PM industry, from raw material suppliers through to equipment manufacturers and nondestructive testing companies. The BEC’s exhibition pavilion is said to offer more than 5,000m2 of dedicated exhibition space and will host more than one hundred exhibitors. In addition to the technical sessions, delegates will have the opportunity to attend seven Special Interest Seminars (SIS) covering the following sectors: • Metal Injection Moulding – Quality and tolerances of MIM components

Euro PM2018 takes place in Bilbao • A critical analysis of press & sinter technology • Soft and hard magnetic materials • Raw materials for a competitive and sustainable Powder Metallurgy industry • Micromechanical testing of hardmetals • Additive Manufacturing case studies and outlook • Hot Isostatic Pressing The full technical programme is available to download via the event website. www.europm2018.com

VACUUM DEBINDING AND SINTERING Advantages at one glance: Thanks to a MIM Box and appropriate gas streams, the system enables users to perform vacuum debinding and sintering in one process cycle, without contamination of the components/hot zone. Vacuum debinding and sintering in one process cycle offers economic benefits in terms of cost and lead time reduction.

www.tav-vacuumfurnaces.com

Vol. 12 No. 3 © 2018 Inovar Communications Ltd

TAV VACUUM FURNACES SPA Via dell’industria, 11 - 24043 Caravaggio (BG) - ITALY ph. +39 0363 355711 - info@tav-vacuumfurnaces.com

September 2018 Powder Injection Moulding International

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Industry News

Gevorkyan adds post-processing and automation capabilities, plans to invest in metal AM Gevorkyan s.r.o., a family-owned business based in Vlkanová, Slovakia, was established more than twenty years ago by military aircraft engineer Artur Gevorkyan. The company reports that it has expanded its manufacturing capabilities in order to offer enhanced solutions to its Metal Injection Moulding and Powder Metallurgy customers. As well as a new hardening operation, a department for automation and robotisation has been established with the intention of accelerating production efficiency. The company’s laboratory has also been expanded with a new metallographic operation. The company currently produces and supplies metal parts made by PM, MIM and HIP technologies to customers in more than thirty

countries worldwide. End-user sectors include the automotive, lock and security systems, garden and hand tool, oil, medical, cosmetic and fashion industries. The company states that it is reasonably independent of the automotive industry, which accounts for 30% of its total portfolio. The majority of its customers come from Europe, North and South America, but also from China or India. The company reports that it develops over a hundred new parts each year and manufactures two thousand different types of component annually. A large part of its component portfolio is made up of PM and MIM components successfully transferred from conventional technologies such as casting or machining.

The Gevorkyan factory All tooling, whether for powder compaction or injection moulding, is prepared in-house. The company also states that it is self-sufficient with regards to secondary operations, including mechanical machining and heat treatment. In 2019, the company plans to install technology for metal Additive Manufacturing. It is already using AM technology for plastic materials in its maintenance department, where AM components are used as spare parts whilst awaiting the supply of original components. www.gevorkyan.sk

龙鼎粉末 METAL POWDERS

Adopting Chinese advanced gas and water combined atomization technology

China’s leading supplier of MIM powders Yingtan Longding New Materials & Technology Company Ltd,. (LDNMT)

powders, and other alloy powders in a variety of particle sizes and tap density based on the demands of its customers. Its product line includes 316L, 304L, 17-4PH, 4J29, F75, HK30, 420W, 440C, Fe2Ni, 4140, and FeSi. Its customers have received its products with high acclaim

Products Index

The company provides various types of structural material powders, magnetic material

Item 316L 17-4PH 304L HK30 4J29

T.D.(g/cm3) 4.80 4.70 4.80 4.70 4.90

S.S.A(m2/g) 0.34 0.34 0.34 0.35 0.36

S.D.(g/cm3) 7.90 7.70 7.80 7.70 7.95

The Address on Bejing Division: No.102, Shangdi MOMA Building 5, Anningzhuang Road, Haidian District, Beijing, China. (Opposite the Xiaomi Science and Technology Park ) Fax: +8610-82815329 Tel: +8610-82815329 Contact : Mr. Cheng Dongkai Mobile: 13911018920 Email: chengdongkai@longdingpowder.com Website: www.ldpowder.com

148-210广告.indd 1

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Industry News

Tekna’s five-year investment plan to expand metal powder production capacity Metal powder manufacturer Tekna Plasma Systems Inc., Sherbrooke, Quebec, Canada, has revealed that it will invest up to $128 million over the course of a five-year plan to expand its global manufacturing output and boost its research and development capabilities. According to the company, these investments reflect a long-term commitment to both the metal Additive Manufacturing, MIM and microelectronics markets. Tekna’s investment plan is expected to help the company increase its global metal powder manufacturing capacity to over 1,000 tons per year; an expansion driven by growing demand from its active customer base. It will include an expansion to manufacturing floor space, the acquisition of production

equipment, and the purchase of resources for product development efforts. The project will benefit from $33 million in financing from the Canadian government. “Building on a portfolio of over one hundred cutting-edge metal powder options, as well as on

our global manufacturing and sales infrastructure, these investments will ensure that Tekna maintains its leadership position,” added Luc Dionne, Tekna’s Chief Executive Officer, “with some of the broadest ranges of metal powders, and one of the greatest capacities available to the 3D printing and microelectronic markets, [we serve] the supply chains of giants in the aerospace, automotive, biomedical and microelectronics industries.” www.tekna.com

The capacity expansion will increase its global metal powder manufacturing capacity to over 1,000 tons a year (Render Courtesy Tekna Plasma Systems)

MIM, CIM & Blast media Established 1993 ISO 9001:2015 Certified NDT department Certified measuring centre Injection overmoulding Customized solutions

www.vibrom.cz

Vibrom spol. s r.o., Orlická 1271, 503 46 Třebechovice pod Orebem, Czech Republic

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September 2018 Powder Injection Moulding International

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Tel: +1 317 337 0441 dwebster@amp-llc.net ldonoho@amp-llc.net


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Tessa Stillman receives MPIF’s 2018 Distinguished Service Award The Metal Powder Industries Federation (MPIF) Awards Committee announced Tessa Stillman as the recipient of its 2018 Distinguished Service to Powder Metallurgy (PM) Award during POWDERMET2018, the International Conference on Powder Metallurgy and Particulate Materials, in San Antonio, Texas, June 17–20. This annual award recognises individuals who have served the North American PM industry in an active capacity for at least twenty-five years and who their peers believe deserve special recognition. Stillman, the MPIF’s Senior Manager, Standards & Technical services, began her career with the federation in 1973 as a part-time typist. Over the years, she has held various management and administrative positions and has worked with numerous boards and committees for the MPIF and APMI. She works closely with the MPIF Technical Board and is said to have guided the annual MPIF/APMI Technical Program Committees, and the related speakers/session chairmen activities, since 1980. Stillman has also been involved in all MPIF standards development work since the early 1980s. She received SAE International’s Forest R. McFarland Award in 2001 for her PM Materials Committee activities and, in 2017, was recipient of ASTM International’s B09 Committee on Metal Powders and Metal Powder Products Distinguished Service Award. After forty-five years working with the MPIF, it was announced that she will retire at the end of this year. Nominations invited for the 2019 Distinguished Service Award The MPIF is seeking nominations for its 2019 Distinguished Service to Powder Metallurgy Award. The

Vol. 12 No. 3 © 2018 Inovar Communications Ltd

Industry News

annual award recognises individuals who have served the PM industry in an active capacity for at least twenty-five years, and who their peers believe deserve special recognition. Recipients will receive their award at the POWDERMET2019 conference in Phoenix, Arizona, USA, June 23–26. 2019. The nomination form can be downloaded from the MPIF website, with all submissions sent by September 15, 2018. www.mpif.org

Tessa Stillman, MPIF Senior Manager, Standards & Technical Services (Courtesy MPIF)

R9 Robot Control

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September 2018 Powder Injection Moulding International

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Industry News

Carpenter reports positive results for its Q4 and full year 2018 MIM powder specialist Carpenter Technology Corporation, Philadelphia, Pennsylvania, USA, has announced its financial results for the fourth quarter and fiscal year ended June 30, 2018. Net sales for its fourth quarter 2018 were reported at $618 million, up from $507.7 million in its fourth quarter 2017 and its highest quarterly sales in six years. Net sales for the company’s

full year 2018 were $2,157.7 million, up from $1,797.6 million in 2017. A net income of $42.8 million was reported for the fourth quarter of the company’s fiscal year 2018 (Q4 2017: $25.5 million). Total net income for the year reported at $188.5 million, a significant improvement on the net income of $47 million reported for the full year 2017.

MIM debind and sinter vacuum furnaces Over 6,500 production and laboratory furnaces manufactured since 1954 • Metal or graphite hot zones • Processes all binders and feedstocks • Sizes from 8.5 to 340 liters (0.3–12 cu ft.) • Pressures from 10-6 torr to 750 torr • Vacuum, Ar, N2 and H2 • Max possible temperature 3,500°C (6,332°F) • Worldwide field service, rebuilds and parts for all makes

MIM-VacTM Injectavac® Centorr Vacuum Industries 55 Northeastern Blvd Nashua, NH 03062 USA Tel: +1 603 595 7233 Fax: +1 603 595 9220 Email: sales@centorr.com

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Powder Injection Moulding International

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Tony Thene, Carpenter’s President and CEO, commented on the results, “Our fourth quarter results marked the culmination of a successful year as strong execution of our strategy, the strength of our increasing solutions-focused customer approach and growing market demand resulted in our best quarterly operating income performance since the fourth quarter of fiscal year 2014.” “Our performance in fiscal year 2018 and, especially during the fourth quarter, demonstrates that our strategy is resonating with customers, and whether it is materials for rotating jet engine parts to medical implant materials to 3D printed parts, we offer the best solutions for our customers,” he concluded. Carpenter’s Performance Engineered Product division, the segment of the company that includes the Dynamet titanium business and the Carpenter Powder Products (CPP) business, achieved net sales for the fourth quarter of the fiscal year 2018 of $116.3 million, up from $106.2 million in the fourth quarter of fiscal year 2017. Operating income for this division was said to be $7.9 million, compared to $5.8 million in the previous year. Thene stated that during its fiscal year 2018, Carpenter has significantly evolved its AM offerings, adding part design and production with its acquisition of metal Additive Manufacturing service provider CalRAM, establishing an AM Technology Center in Reading, Pennsylvania, USA, and developing its capabilities as a small-scale AM solutions provider. Looking ahead to 2019, he stated that Carpenter will rapidly evolve to offer end-to-end AM solutions across multiple industries. He pointed to the company’s planned opening of an Emerging Technology Center in Athens, Alabama, USA, in twelve months, and its involvement as a founding partner in GE Additive’s Manufacturing Partner Network, as further evidence of its commitment to developing its presence in AM. www.cartech.com

© 2018 Inovar Communications Ltd

Vol. 12 No. 3


Reinvent how you manufacture with RenAM 500Q

1 × laser

2 × lasers

RenAM 500Q is Renishaw’s new quad laser AM system. It features four high-powered 500 W lasers, each able to access the whole powder bed surface simultaneously. RenAM 500Q achieves significantly higher build rates without compromising quality, vastly improving productivity and lowering cost per part. • Full field of view for all lasers for optimum production efficiency • Enhanced gas flow to provide consistent high quality processing • Faster turn-around between builds with improved automated powder and waste handling systems

For more information visit www.renishaw.com/renam500q

Renishaw plc Brooms Road, Stone Business Park, Stone, Staffordshire, ST15 0SH, United Kingdom T +44 (0)1785 285000 F +44 (0)1785 285001 E additive@renishaw.com

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4 × lasers


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Industry News

Award winning parts showcase the capability of Metal Injection Moulding technology The international Metal Injection Moulding industry accounted for a significant proportion of the winning parts in the Metal Powder Industry Federation’s (MPIF)

2018 Powder Metallurgy Design Excellence Awards competition. The winners were announced during the POWDERMET2018 International Conference on Powder Metallurgy

and Particulate Materials, San Antonio, Texas, USA, June 17-20, 2018. The parts showcase the ability of Metal Injection Moulding to deliver complex, high-performance and cost-saving solutions for end-users in a diverse range of end-user sectors, from automotive and aerospace to medical devices and firearms.

Grand Prizes Aerospace/Military/Firearms: Indo-MIM Pvt. Ltd. The Grand Prize in the Aerospace/ Military/Firearms Category was won by Indo-MIM Pvt. Ltd., India, for three metal injection moulded stainless steel parts: a rear insert, a slide stop and a trigger lever (Fig. 1). Together, the three parts form an assembly that goes into the P10 9 mm pistol. All three parts have extremely complex geometries that would be extremely difficult to achieve by machining.

Fig. 1 Indo-MIM Pvt. Ltd’a insert rear, slide stop & trigger lever won a Grand Prize in the Aerospace/Military/Firearms category (Courtesy MPIF)

Fig. 2 AMT Pte, Ltd’s EPR Flow Block won a Grand Prize in the Hardware/ Appliance category (Courtesy MPIF)

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Hardware/Appliance: AMT Pte, Ltd The Grand Prize in the Hardware/ Appliance Category went to AMT Pte, Ltd, Singapore, for a metal injection moulded stainless steel EPR flow block single sensor (Fig. 2). The component, part of the specimen inlet module of gas chromatography analytical equipment, includes two dedicated internal channels to manage gas in and out of the five ports without permitting leakages. Forming these 90° internal channels required the use of a hydraulic core-pull slider system. By integrating multiple, formerly cast- and-machined parts into one metal injection moulded component, the complex geometry proved challenging for tool design as well as for the MIM process. The sensor is processed close to net-shape, with the tapping of threads in the pre-formed holes being the only secondary operation performed.

© 2018 Inovar Communications Ltd

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Industry News

Medical/Dental: ARC Group Worldwide The Grand Prize in the Medical/ Dental Category was awarded to ARC Group Worldwide for a MIM 17-4 PH size 5 cutting block made for Smith & Nephew (Fig. 3). The block goes into the recently launched Visionaire FastPak Single Use Instruments used in knee-replacement surgery. The extreme complexity created by the overall size of the component, which weighs in at nearly 450 g (1 lb), combined with non-uniform wall thicknesses and the need for stress mitigation for finished machining operations, makes this a highly challenging part to process via MIM. The MIM component is estimated to save 60% in cost over traditional manufacturing methods.

Fig. 3 ARC Group Worldwide’s cutting block won a Grand Prize in the Medical/ Dental category (Courtesy MPIF)

Electronic/Electrical: ARC Group Worldwide The Grand Prize in the Electronic/ Electrical Category went to ARC Group Worldwide for a MIM stain-

less steel shaft grounding guide section made for Cutsforth, Inc (Fig. 4). The guide section is part of the customer’s Shaft Grounding System used in brush excitation

maintenance on turbine generators in the nuclear, gas, coal, wind and hydro industries. Although the part design has many undercuts due to the nature of the

Fast MIM NEW FASTER 3D METAL PRINTING

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Industry News

Awards of Distinction Automotive-Engine: Indo-MIM Pvt. Ltd Another Award of Distinction in the Automotive-Engine Category was won by Indo-MIM Pvt. Ltd., India, for a MIM stainless steel fuel-inlet orifice used in fuel rail systems of diesel engines in Ford vehicles (Fig. 5). The metal injection moulded part is formed close to net shape, requiring only bright annealing to remove surface oxidation and enhance brazing. The previously machined part was redesigned for MIM in order to overcome the difficulty of producing tapered holes from opposite ends that are free of burrs at their meeting point. The two perfectly aligned holes are achieved using two slides.

sliding track features, its design still allows for a twoplate mould without any slides. By controlling features such as gate location, fill time, hold pressure and barrel temperature, the MIM process was optimised to produce aesthetically pleasing near net shape components.

Aerospace/Military/Firearms: ARC Group Worldwide An Award of Distinction in the Aerospace/ Military/ Firearms Category was presented to ARC Group Worldwide for a MIM low-alloy steel trigger bar made for Honor Defense (Fig. 6). The nearly 75 mm (3 in) long pistol part is made up of several complex contours with thin cross-sectional areas, making it impossible to hold distortion free through sintering. Several secondary processes, utilising a high-resolution multi-view camera system, were optimised to allow micro-adjustment of each contour to meet the profile requirement, while still delivering cost effectiveness compared with the original machined part.

Fig. 5 Indo-MIM Pvt. Ltd.’s orifice fuel inlet won an Award of Distinction in the Automotive: Engine category (Courtesy MPIF)

Fig. 6 ARC Group Worldwide’s trigger bar won an Award of Distinction in the Aerospace/Military/Firearms category (Courtesy MPIF)

Fig. 4 ARC Group Worldwide’s shaft grounding guide won a Grand Prize in the Electronic/Electrical category (Courtesy MPIF)

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Industry News


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Industry News

to redirect gases and reduce the effects of recoil. Innovative gating and sintering strategies enabled tolerances to be maintained without secondary sizing or bending operations. In a relatively untapped market for MIM, this new part demonstrates perfectly the complexity, overall size and cost-effectiveness that MIM offers.

Fig. 7 ARC Group Worldwide’s compensator brake won an Award of Distinction in the Aerospace/Military/Firearms category (Courtesy MPIF)

Aerospace/Military/Firearms: ARC Group Worldwide A further Award of Distinction in the Aerospace/Military/Firearms Category was presented to ARC Group

Worldwide for two MIM stainless steel compensator brakes – a 5.56 and a 7.16 calibre – made for Sig Sauer (Fig. 7). The parts are attached to short-barrelled rifles

Hand Tools/Recreation: Indo-MIM Pvt. Ltd An Award of Distinction in the Hand Tools/Recreation Category went to Indo-MIM Pvt. Ltd., for a MIM stainless steel passive plus body that goes into a safety assembly of mountaineering equipment (Fig. 8). Together with a Kevlar rope and a carabiner to which it is assembled, the part helps to lock the rope in the event of a slip. Sophisticated shut-offs in the tooling were required in order to achieve the complex internal geometry, which is produced to

Atect PIM feedstocks

Using Atect Full-Mould binders

atect Feedstocks atect atect Feedstocks atect Feedstocks Feedstocks • Best combinationUsing of flowability and viscosity • Minimised binder residue thanks to ‘thermal atect Full-Mould Binders atect Feedstocks atect Feedstocks Using Using atect Using atect Full-Mould atect Full-Mould Full-Mould Binders Binders Binders for excellent injection quality only’ complete decomposition Best combination of atect flowability and viscosity for excellent injection quality Using Using Full-Mould atect Full-Mould Binders Binders Best combination Best combination Best of combination flowability of flowability and of viscosity flowability and viscosity forand excellent viscosity for excellent injection for excellent injection qualityinjection quality quality expansion the mould by Barus effect for excellent transferability • High expansionHigh in the mouldin through the • Extraordinary shape retention and rigidity Highbinder expansion High residue expansion High in the expansion mould in the mould byonly inBarus the by mould Barus effectby for effect Barus excellent foreffect excellent transferability for excellent transferability transferability Minimize by thermal complete decomposition

Best combination Best of flowability combination and of viscosity flowability forand excellent viscosity injection for excellent quality injection quality Barus effect forExtraordinary excellent transferability eliminates secondary machining Minimize Minimize binderMinimize binder residue residue by binder thermal by residue thermal only by complete only thermal complete decomposition only complete decomposition decomposition shape retaining rigidity eliminating secondary machining

Flow index (volume/time)

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Powder Injection Moulding International

polymer) polymer)moldingpolymer)

E-mail: pimsales@atect.co.jp E-mail:E-mail: pimsales@atect.co.jp pimsales@atect.co.jp E-mail: pimsales@atect.co.jp

www.atect.co.jp pimsales@atect.co.jp E-mail: pimsales@atect.co.jp E-mail: pimsales@atect.co.jp September 2018

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Vol. 12 No. 3


Time to rethink your components with MIM? STRONG ER, BETTER, FASTER,...

Sintex can help you to rethink your components and make them stronger, better, faster, more competitve – or something completely different. Located in Denmark – and with Metal Injection Moulding (MIM) as our core competence – our focus is on creating high-quality components in the most efficient, innovative and automated production facilities. We believe that this is the way to create the best component and significant value for our customers. www.sintex.com

<


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Industry News

Fig. 8 Indo-MIM Pvt. Ltd.’s passive plus body won an Award of Distinction in the Hand Tools/Recreation category (Courtesy MPIF)

Fig. 9 Indo-MIM Pvt. Ltd.’s hearing aid enclosure won an Award of Distinction in the Medical/Dental category (Courtesy MPIF)

net shape. A small sizing operation and heat treatment, as well as grit blasting for the part’s finish, are the only secondary operations.

aid enclosure (Fig. 9). Both MIM parts are fabricated to near-net shape, with the cup only having a sizing operation to bring its overall dimensions within specification and the cover finish undergoing glass-bead blasting. The extremely thin walls of the parts, as well as complex features such as holes, pips, and pips with holes, would make this component more difficult and more expensive to produce using any other conventional method.

Medical/Dental: Indo-MIM Pvt., Ltd An Award of Distinction in the Medical/Dental Category went to Indo-MIM Pvt. Ltd., India, for two permalloy parts – a cup and a cover – that are assembled to form a hearing

Electronic/Electrical: ARC Group Worldwide An Award of Distinction in the Electronic/Electrical Category was presented to ARC Group Worldwide for a MIM stainless steel upper beam handle made for Cutsforth, Inc (Fig. 10). The part goes into an EASYCHANGE Removable Brush Holder assembly used in turbine generators in the power industry. Redesigned from a previously 100%-machined part, the as-moulded component, with its many intricate details, needs only one slight machining operation to meet tolerance and functional requirements. The MIM process reduced the per part cost by 60%. www.mpif.org

PolyMIM GmbH is a manufacturer that offers two different binder systems for metal injection molding: • polyPOM – our catalytic binder system • polyMIM – our water soluble binder system These two binder systems have excellent characteristics during the production process and combine attractive prices with worldwide availability. Our portfolio includes products for mass production for the telecommunication and automotive industries as well as the high-end sector with our special alloys. Please be informed that PolyMIM is participating from 14 th to 18th of October at the Euro PM2018 in Bilbao, Spain. You’re Welcome to visit us at our exhibition booth #98 PolyMIM GmbH Am Gefach 55566 Bad Sobernheim, Germany Phone: +49 6751 85769-0 Fax: +49 6751 85769-5300 Mail: info@polymim.com

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Fig. 10 ARC Group Worldwide’s upper beam handle won an Award of Distinction in the Electronic/Electrical category (Courtesy MPIF)

September 2018

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Vol. 12 No. 3


U.S. Metal Powders, Inc. A M PA L | P O U D R E S H E R M I L L O N

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Shaping the Future Together United States Metal Powders, Inc. has been a global leader in the production and distribution of metal powders since 1918. Together with our partners and subsidiary companies, AMPAL and POUDRES HERMILLON, we are helping to shape the future of the metal injection molding industry (MIM). Dedicated Research, Leading Edge Technology, Global Production & Customization • Aluminum alloy powders • Nodular and spherical aluminum powders • Aluminum based premix powders

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Industry News

New binder system for improving titanium Metal Injection Moulding The binder systems used in Metal Injection Moulding play a crucial role in the successful processing of defect-free Ti components. Binders include components of plasticiser (the primary component), polymers (the backbone component) and surfactants, with a combination of these in the metal powder-based feedstock allowing the safe handling of the injection moulded parts during subsequent debinding and sintering. In particular, adequate green strength should be provided by the backbone polymer after the removal of the primary binder. In the MIM of titanium, the reactivity of the powder with impurities such as carbon, which is present in all binders, and the high affinity of the Ti powders for oxygen, pose additional requirements.

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A paper by M D Hayat, et al, (University of Auckland, New Zealand), published in Powder Technology, Vol. 330, 2018, pp. 304–309, describes the development of a new binder system which meets the challenge of providing feedstock homogeneity and good green strength in injection moulded Ti parts. The authors had previously studied the use of polyethylene glycol (PEG), poly(propylene carbonate) (PPC)-based binders and found that, whilst they showed promising results in terms of feedstock homogeneity and thermal degradation behaviour, the injection moulded samples showed a complete loss in dimensional stability because of insufficient green strength. They therefore sought to modify the PEG/PPC binder by adding a small amount of

Powder Injection Moulding International

September 2018

poly(methyl methacrylate) (PMMA). PPC and PMMA are suitable as backbone binders, with both being water insoluble, and the addition of PMMA was found to provide the necessary properties to achieve adequate green strength of the injection moulded Ti parts until the initial stage of sintering. The authors used a commercial purity gas atomised Ti powder having spherical particle shape and nominal particle size of < 45 µm. Interstitial contents in the Ti powder were 0.122 wt.% O2, 0.003 wt.% C and 0.008% N2. The modified binder for Ti-MIM contained 73 wt.% watersoluble PEG, 20 wt.% PPC, 5 wt.% PMMA and 2 wt.% SA (Feedstock A). Powder loading in the feedstock mixture was 67 vol.% based on capillary rheometer experiments. As a comparison the binary PEG/ PPC (73:25 by wt.%) with 2 wt.% SA binder feedstock (Feedstock B) was also used in order to evaluate the effect of PMMA in the ternary blend.

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Both feedstocks were injection moulded at 130°C, mould temperature of 25°C, injection pressure of 90 MPa and cooling rate of 10 s. Water debinding was conducted to remove PEG and thermal debinding of the remaining binder was carried out under a purging argon gas and under a high vacuum. The resulting poor shape retention of Feedstock B was attributed to insufficient interaction/binding between PEG and PPC even though the mixture was homogeneous after mixing, as confirmed by SEM. The addition of PMMA, even in small amounts, in the binder system was considered to reduce PPC leaching during the water debinding stage, thereby increasing green strength. The authors reported that the thermal degradation of the less stable PPC starts at around 200°C. The initial weight loss of 17% at 200°C implies that PPC was almost completely decomposed followed by the decomposition of PEG. This binder decomposes completely around 320–340°C. The addition of only 5 wt.% PMMA in the PEG/ PPC blend system shifts the onset decomposition temperature of the binder from 230°C to a higher temperature of 300°C and ending at 430°C with the addition of PMMA broadening the temperature range over which the second weight loss takes place. Thus, PMMA increases the thermal stability of the binder system, which could be attributed to the chemical interactions between PPC and PMMA, and leads to significantly improved green strength and adequate dimensional stability for subsequent thermal processing. It was also found that the complete combustion of the water insoluble backbone polymers PPC and PMMA at relatively low to moderate thermal treatment temperatures did not produce undesirable impurities after thermal debinding. The authors reported that thermal debinding under argon gas leads to a higher content of oxygen (0.25 wt.%) compared to thermal debinding in

Industry News

high vacuum (0.17 wt.%). However, in both these cases, the impurity contents of the thermally debound samples are well below the maximum permitted limits of the relevant ASTM standard (0.30 wt.%). They also reported that whilst oxygen pick-up during sintering cannot be completely avoided, it can be kept to a minimum level using a clean, high vacuum sintering furnace (vacuum 10−2 Pa or better). They concluded that, based on the current research, the impurity contents under high vacuum managed to

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achieve levels meeting ASTM standard F2989-13 Grade 1 quality during thermal debinding, which suggests that high-quality titanium parts can be produced using this binder system if a high vacuum sintering furnace is used. Further investigations of debinding and sintering processes in relation to this binder system for Ti-MIM are planned. www.auckland.ac.nz www.journals.elsevier.com/ powder-technology

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Promising properties achieved with MIM of non-spherical HDH titanium powders MIM has been used extensively in recent decades to produce near net shape small- to medium-size intricately shaped components in high volumes using metal and alloy powders. However, in the case of titanium powders, progress in using MIM as a manufacturing process has been relatively slow due in the main to the high cost of low-oxygen content fine spherical powders (≤ 45 micron). However, non-spherical hydride-dehydride (HDH) titanium powder with higher oxygen content is readily available at a fraction of the cost of low-oxygen spherical titanium powders and efforts are underway to develop viable processes for the Metal Injection Moulding of HDH Ti powders. In a paper by A Dehghan-Manshadi and colleagues published in the Journal of Manufacturing Processes (Vol. 31, 2018, pp. 416-423), the pim international 2016-09.pdf

1

authors presented the results of collaborative research undertaken at the Queensland Centre for Advanced Materials Processing and Manufacturing (AMPAM), St. Lucia, the School of Engineering, RMIT University, Melbourne, Australia, and Baosteel Special Metals Ltd, Shanghai, China, into identifying suitable process parameters for MIM of HDH Ti powder. The researchers used a non-spherical HDH Ti powder having an average particle size of 45 µm and purity of 99.0%. The Ti powder particles contained pores and crevices, which absorb extra binder, so that, whereas a 70 wt.% powder loading can be used for a spherical Ti powder, the optimum loading in the HDH Ti powder is around 61%. However, the authors state that this is still higher than previously reported research on MIM of HDH Ti powder.

The HDH Ti powder is mixed with a binder system consisting of 61 wt.% paraffin wax, 36 wt.% high density polyethylene and 3 wt.% stearic acid. A dry mixture of the HDH Ti powder and binder was loaded into a twin screw extruder, preheated to 175°C and extruded ten times to produce a uniform mixture. This extrusion exercise showed that, after ten times extrusion of the mixture, the pressure inside the extruder barrel is minimal, indicating a well-mixed feedstock. The mixture was then cooled to room temperature and manually crushed into pellets of < 3.0 mm to form the feedstock for the MIM process. After moulding, the MIM test bars were immersed in a hexane bath at 50°C for 20 h to remove the paraffin wax component of the binder system. Thermal debinding was performed by slow heating of samples to 550°C under argon at a flow rate of 3 l/min. The researchers undertook sintering experiments using a variety of temperature-time combinations, with sintering performed in a vacuum

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Sales Agent in Europe Burkard Metallpulververtrieb GmbH Tel. +49(0)5403 3219041 E-mail: burkard@bmv-burkard.com

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of 10−3 Pa. The combination of a sintering temperature of 1250°C and a time of 120 min was found to be the most promising isothermal sintering condition, leading to a relatively high sintered density of 96.5% accompanied by longitudinal shrinkage of 13.6% for MIM of HDH Ti. The results of sintering at different temperatures for 120 min on shrinkage and density are shown in Fig. 1. An examination of the sintered Ti microstructure showed that the material was nearly pore-free in the surface layer (almost 100 µm) compared with the central region of the sintered sample. The encouraging tensile properties (tensile strength = 395 MPa, elongation = 12.5%) obtained from sintering at 1250°C for 120 min confirmed that the temperature-time combination of 1250°C for 120 min can serve as a suitable sintering condition for MIM of HDH Ti. The tensile strength is higher than that of mill-annealed ASTM Grade 3 CP Ti but lower than that of the ASTM Grade 2 CP Ti.

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Fig. 1 Shrinkage and relative density calculated based on the theoretical density of 4.51 g/cm3 for CP-Ti of MIM HDH Ti samples after sintering at different temperatures for 120 min. (From paper by A Dehghan-Manshadi, et al, Journal of Manufacturing Processes Vol. 31, 2018, pp. 416-423) The oxygen level of the sintered MIM Ti samples in the current study is higher than expected, which is attributed to the high oxygen level in initial HDH powders. While this high oxygen level (along with the presence of 3–4% porosity) is not desirable, the MIM-processed samples still offer 10–12% tensile elongation, which meets the criterion required for most

wrought titanium alloys including Ti-6Al-4V in the mill-annealed condition. The authors concluded that MIM of HDH Ti has potential for structural applications in many industry sectors and at a significant cost-advantage compared with MIM of spherical Ti powders. www.journals.elsevier.com/journalof-manufacturing-processes

EMBEMOULD® MIM - feedstock | MIM & CIM binders At eMBe we have the products and services to help you „shape up“ your metal or ceramic powders, from binders for solvent or water debinding to ready-to mould feedstock. Develop your individual products with us by using our in-house laboratory and extensive experience as one of Europe´s leading PM additive suppliers. Our services focus on product development and product innovation to continuously meet our customers’ evolving needs worldwide.

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Numerical simulation of stress distribution during supercritical debinding of MIM Inconel 718 Debinding of powder injection moulded components made using highly loaded mixtures of metal or ceramic powders and thermoplastic polymers is generally carried out using solvent, thermal or catalytic processes. The solvent debinding step to extract the soluble polymer in the green PIM parts can be undertaken using water or a conventional solvent, but this can be time consuming due to the low diffusion rate of the polymer. An alternative and quicker route to solvent debinding is to use a fluid in a supercritical state, for example carbon dioxide (CO2). The supercritical CO2 is obtained at a pressure of 7 MPa and temperatures up to 304K and has been found to be very effective as a debinding agent as well as being more environmentally friendly because it produces no VOC emissions. Researchers at the Femto-ST Institute, University of Bourgogne Franche-Comte, Besançon, France, have been studying the use of CO2 supercritical fluid instead of a regular solvent for the extraction of organic binder in MIM components based on Inconel 718 superalloy powder. In a paper presented at the 21st International Conference on Material Forming (ESAFORM), held in Palermo, Italy, April 23-25, 2018, and published in AIP Conference Proceedings Vol. 1960, Aboubakry Agne and Thierry Barriere described their recent research into the effect that the high temperature and pressure used in supercritical debinding using CO2 can have on the stress and deformation on the outer surfaces of MIM Inconel 718 components, caused by differentiated thermal expansion and binder extraction. In a previous paper [1] the authors had shown that polyethylene glycol (PEG), a soluble polymer, is totally removed by supercritical CO2 from a MIM component produced from feedstock containing Inconel 718 powders, polypropylene, polyethylene glycol and stearic acid as binder. They also modelled the polymer extraction

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process and found the results to be in good agreement with the experiment. The optimal conditions in terms of temperature and pressure of supercritical debinding were found to be 423 K and 40 MPa and these conditions were used in the present study which focused on analysing the stress distribution, fluid flow and deformation of a MIM Inconel 718 cylindrical component. The authors stated that, during supercritical debinding, three phenomena may induce deformation and stress inside the component: the extraction of polymer, the effect of the supercritical fluid on the component and the thermal expansion due to heat transfer. The shrinkage due to removed polymer measured after supercritical debinding can be negligible (less than 1%). The fluid’s effect on the mechanical structure and thermal expansion during the process are probably the main phenomena that can produce severe stress during the debinding step. Fig. 1(a) shows a diagram of the supercritical debinding equipment used in the research. Gaseous CO2 is first extracted and cooled to a liquid state before being pumped to a pressure necessary to achieve the supercritical state. The CO2 is heated and fed into the cylindrical reactor (Fig. 1(b)), which contains the green MIM part. The CO2 is then recovered and cooled, and a recycling line separates the extracted organic binder materials and CO2. The reactor and the cylindrical reactor were modelled in two dimensions (2D) by finiteelement method (FEM) and simulated using the fluid-structure interaction. The 2D axisymmetric model coupling fluid-structure interaction was performed using the Comsol Multiphysics finite-element® software platform with a stationary solver to analyse the stress distribution, the fluid flow and the deformation of a cylindrical component. The resulting numerical simulation could be used

Powder Injection Moulding International

September 2018

(a)

(b)

Fig. 1(a) The supercritical debinding equipment and (b) the reactor and the cylindrical green MIM part in 2D used to generate numerical debinding simulations. (From paper by A Agne and T Barriere, ‘Numerical simulation of stress distribution in Inconel 718 components realised by Metal Injection Moulding during supercritical debinding’, published in AIP Conference Proceedings, Vol. 1960, 2018) to analyse how the supercritical fluid affects the component and if the stress can produce defects during the polymer extraction. The authors stated that the results show that the mean stress inside the component is less than the fluid’s pressure. This low stress is due to the low velocity on the outer surfaces of the component. However, there is a shrinkage of 0.25% during the process and the component undergoes swelling and elongation due to the pressure applied by the supercritical CO2 fluid and to the thermal dilation, respectively. It was found that the high pressure of the supercritical CO2 debinding agent does not produce defects inside the component. [1] A Agne and T Barriere, ‘Modelling and numerical simulation of supercritical CO2 debinding of Inconel 718 components elaborated by Metal Injection Moulding’, Appl. Sci. Vol. 7, 2017, 1024 www.femto-st.fr

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Stainless Steel Powders for MIM, Additive Manufacturing, & Other Fine Powder Applications More than 30 years ago, AMETEK developed a proprietary method of producing and processing fine metal powders to meet our customers’ exacting specifications. Our ongoing commitment to innovative and advanced metallurgical technology, customized formulations, grades, and sizing that support MIM, Additive Manufacturing, and other Fine Powder applications make AMETEK your supplier of choice! Austenitic Stainless Steel Standard grades include P303L, P304L, P309L, P310L, and P316L. Other grades available upon request. Ferritic Stainless Steel Standard grades include P409, P410L, P420L, P430L, P434L, and P446. Other grades available upon request. 17-4 PH Precipitation Hardening Stainless Steel Leading producer of 17-4 PH and 70/30FeCr master alloy. Other specialty alloys include NiCr, NiAl,  PM400, PN200, PT400, and PNF50.

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Mouldability and segregation of low pressure injection moulded Inconel 718 Low Pressure Injection Moulding (LPIM) using pressures lower than 1 MPa has become an attractive alternative to High Pressure Injection Moulding (HPIM), which requires moulding pressures up to 200 MPa. Recent research undertaken by Vincent Demers and colleagues at Ecole de Technologie Superieure, Montreal, the Polytechnique Montreal and Pratt & Whitney, Canada, has focused on the suitability of several feedstocks based on Inconel 718 powder for LPIM and, in particular, on the viscosity and segregation of such feedstocks. The team’s findings were recently published in Advanced Powder Technology, Vol. 27, 2018, pp. 180-190. In their report, the authors stated that the main difference between HPIM and LPIM manufacturing technologies lies in the binder viscosity used for powder transportation during the injection stage, and that low-viscosity feedstocks formulated with low molecular weight polymers have been used in LPIM to increase mouldability and shape complexity in the manufacture of metallic parts. They further stated that a LPIM feedstock is generally designed to minimise segregation and should also maximise mouldability, provide adequate green strength in the moulded component, maximise the solids loading potential and maximise the debinding potential. Their focus in this project was placed on the study of the mouldability and segregation criteria. Both these criteria are linked to the rheological behaviour of the feedstock, for which there is a compromise between these two parameters. Using too low a feedstock viscosity should easily fill the mould cavity, but would also lead to heterogeneity of solids loading within the green part. Conversely, mouldability and segregation are both reduced if a feedstock with too high a viscosity is used. Therefore, the ideal feedstock viscosity should minimise the segregation parameter without

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compromising the mouldability parameter, and vice versa. The authors used gas atomised Inconel 718 having typical particle size of 12 µm. They used this powder to formulate nineteen different feedstocks, which were referenced by their volume fractions of constituent binder such as paraffin wax (PW), ethyl vinyl acetate (EVA), used as thickening agent, and stearic acid (SA) as surfactant. SA and EVA were blended in different proportions with paraffin wax. Powder loading in the feedstocks ranged from 61 vol.% to 74 vol.%, although solids loading higher than 70 vol.% was used only to assess the critical solids loading. Each powder-binder mixture was injected into a hot mould (90°C) for time periods ranging from 1 min, 10 min and 60 min to produce cylindrical shapes (9.5 mm diameter, 35 mm tall), which were rapidly cooled to room temperature. The time between injection moulding and solidification of the feedstocks ranged from a few seconds to a few minutes, but the authors extended this to 60 min in order to foster the segregation of the powder. As can be seen in Fig. 1, all mixtures of PW and SA generated a similar rheological behaviour regardless of the proportion of surfactant used. An addition of 1–20 vol.% of SA in PW was found to generate a significant decrease in the viscosity values of feedstocks as measured by a rotational rheometer, as well as a change in the shape of the viscosity profile, compared to the feedstocks formulated from paraffin wax (40PW) alone. The EVA thickening agent may also generate an intricate effect on viscosity. For example, a small addition of EVA (39PW-1EVA) was stated to induce a significant decrease in viscosity values along the majority of the shear rate range compared to the feedstocks formulated from wax (40PW) alone. From a mouldability perspective, the low and constant viscosity values over

Powder Injection Moulding International

September 2018

Fig. 1 Viscosity profiles for feedstocks formulated from paraffin wax (PW) + surfactant agent (SA) and wax + thickening agent (EVA). (From paper: ‘Experimental study on moldability and segregation of Inconel 718 feedstocks used in low-pressure powder injection molding’, by V Demers, et al, Advanced Powder Technology Vol. 29, 2018, pp. 180–190) the medium-to-high shear rate range indicate the potential of this feedstock to be injected at low pressure into complex shapes. Segregation within green parts was evaluated using a thermogravimetric analyser. It was found that the variation in solids loading within a moulded part can be measured with a sensitivity of at least ± 0.25 vol.% of powder. The results also indicated that the predominant powder-binder separation appears clearly at the top and the bottom of the moulded part and that the intensity of segregation depends both on the binder constituents used in feedstock formulation as well as the viscosity profile of the feedstock. The mixture containing only paraffin wax produced the best trade-off between high mouldability and low segregation for an injection process requiring an extended time range between injection and solidification of the part (e.g. ≤ 10 min). For a short processing time (e.g. < 1 min in molten state), the feedstocks containing PW with SA, or a small amount of EVA can be also be considered as good candidates for the LPIM process because their viscosity and segregation potential are relatively low. www.journals.elsevier.com/ advanced-powder-technology

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Ten rules for MIM success

Design for Metal Injection Moulding: Ten rules to save time, reduce costs and improve quality Developing a component for a new manufacturing process can be a daunting prospect. It is in any business’s nature to be cautious of change and to minimise risk; however, any successful business must also recognise when an opportunity is too good to ignore. It is the latter that has driven such dramatic growth in the global MIM industry over the last decade. For those who are just at the point of discovering this technology, Matt Bulger reveals the ten key rules for MIM success, as observed in his nearly three decades as a developer and manufacturer of MIM components.

In the early days of the Metal Injection Moulding industry, in the 1980s, it was a given that the original drawings and specifications for a potential MIM part were conceived with another technology in mind, typically machining or casting. Early MIM producers yearned for the day when a part would be specifically designed for the MIM process: this would give the customer a more effective part, production and development would follow a more straightforward path, and economics, quality and efficiencies would improve for all involved parties. Today, with MIM market acceptance and awareness at a much higher level, there are many alert designers who can identify parts which are candidates for MIM at an early stage in the design process. This presents an excellent opportunity for MIM producers to share general design advice, giving best chance possible to produce a successful component. Following are some basic considerations for component design and specification that should benefit all parties. These factors can directly affect the manufacturability of the part, which will then impact cost, quality, lead-time, etc.

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The following points are not intended to be a comprehensive design guide; they are general observations for a typical MIM process and the results will almost certainly vary from operation to operation. These are high-level observations that are potentially already understood but are easily overlooked.

1

Make sure the material and processes required are suitable for MIM Today there are many materials available in MIM with known properties, so, if at all possible, pick one with good industry support and

Fig. 1 MIM is a mature manufacturing process capable of extremely high production volumes. However, to benefit from this capability, it is important that key ‘Design for MIM’ guidelines are followed

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UNSPECIFIED TOLERANCES .XXX = ±.005 .XX = ±.015 .X = ±.050 MACHINE FINISH 125 MAX. ANGLES = ±1° REMOVE ALL BURRS BREAK SHARP CORNERS THIRD ANGLE PROJECTION

+ Fig. 2 Standard tolerance block with ‘reasonable’ MIM tolerances

Option 1 - BAD: 50.00 mm + 0.00, - 0.50 mm Option 2 - GOOD: 49.75 mm +/- 0.25 mm

Fig. 3 Two ways to specify the same dimension, each with a total tolerance band 49.50–50.00 mm

Shrink rate of 18.2% in the Z dimension

Y

Shrink rate of 17.6% in the Y dimension

Z X

Shrink rate of 17.8% in the X dimension

Fig. 4 Rectangular bar with example shrinkage rates in the X, Y and Z dimensions

documentation. One way in which this can become tricky is when seemingly unrelated design requirements create conflicts. For example, a part design can specify a heat treated low alloy steel because the application needs

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strength and hardness. That material is then specified to undergo ferritic nitrocarburising, sometimes known as Melonite, among other trade names. Ferritic nitrocarburising is often specified because it delivers an attractive black surface finish with

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excellent wear resistance. However, the temperature of that process is typically well over 500°C for a time of 25 minutes or longer, and this combination of temperature and time will anneal just about any heat treated low alloy steel. What started off as a heat treated steel is heat treated no longer. As the old saying goes: “You can’t have your cake and eat it too!”

2

Do not over-specify default tolerances

When designing a part, the temptation is to specify an ultra-accurate component. Why not? MIM is sold as an extremely precise net-shape process. However, this can come at the expense of making a more easily produced - and thus more economical - part. One overlooked path to this result is through overly stringent default tolerances in the drawing title block (Fig. 2). While the tolerances seen here are reasonable, it only takes a few keystrokes to make these tighter (i.e. for .XXX inch tolerances, some drawings are now specified to +/- 0.002 in. instead of the historical default of 0.005 in.). These tightened tolerances apply globally across the print. It is not unusual to end up in a situation where a non-critical tolerance ends up being specified much more tightly than a critical-to-function requirement that the designer has specified directly. Many first prototypes can be delayed, or a tooling rework required, simply because the component is over-specified for no functional benefit. As a corollary issue, there is often difficulty in having a print changed once issued. Suppose a design gets through review and no one notices that the requirements dictated by the default tolerances cannot be met by the quoted MIM process. Even for a requirement that is not critical to function, the designer will not be inclined to change the print, because what is their incentive? If there is a problem down the road, the finger is pointed at the designer

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Ten rules for MIM success

Fig. 5 MIM tooling, particulary for large and highly complex components such as this smartphone frame, requires significant investment. It is therefore important that key tolerances, gates, ejection pin locations, etc, are carefully considered in conjunction with a MIM producer at the earliest phase of a component’s development (Courtesy Arburg)

as the person that allowed the looser tolerance. Changing the print can look to the designer like a no-win scenario. The bottom line is that it is best to have these items addressed early in the part development.

3

Ensure that the part model reflects nominal part requirements The key issue here is that MIM tolerances will always have a +/- variation around the standard shrinkage from the tooling. One basic reason is that moulded and sintered parts always have slightly varying densities, which make individual parts, to some extent, larger or smaller. However, on a part print, the designer may specify an ‘unbalanced’ tolerance to show design intent. For example, let’s say a component has a 50 mm dimension. The designer absolutely does not want the dimension to exceed 50 mm, so on the

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print it is specified as “50.00 mm + 0.00 mm, - 0.50 mm.” The span of allowable tolerances is 49.50 mm – 50.00 mm which has a 49.75 mm nominal. If the part model is created from the print and the part model informs the toolmaker that the dimension should be 50.00 mm, then the steel in the tooling will be made at the top end of the spec (50.00 mm) instead of the nominal (49.75 mm). Tooling built in this way virtually ensures that the result will include a sizable percentage of components made outside the specification because it was not built to the nominal 49.75 mm desired. Forget any chance of meeting a decent Cpk under those conditions! So, at some point in the design process, verification will be needed that the model reflects part nominals (Fig. 3), no matter what the design intent may be. Rest assured that the tool maker will always revert to the model.

4

Remember that not all shrinkage is isotropic

It is generally acknowledged in the MIM industry that most, if not all, MIM processes will create parts that will not shrink by the same amount along different axes (Fig. 4). This differential rate of shrinkage is extremely difficult to predict in advance. If the tooling

Y

X

Fig. 6 If there are differing shrinkage rates in the X and Y direction, it will create an oval, not a straight cylinder

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90° to each other) will create ovality in cylinders and internal diameters (Fig. 6), thus forcing dimensions with tight circularity requirements to be machined. When compared to other established technologies, MIM’s relative lack of cylindrical accuracy puts it at a competitive disadvantage to processes such as screw machining and hobbing. Don’t go into a MIM operation looking to find a bunch of gears!

5

Make all critical dimensions ‘steel-safe’ in the tool

A

B

Fig. 7 This award winning MIM part from ARCMIM has features where ‘steelsafe’ tool design should be considered. At point A, the internal diameter tooling should be made to the high end of specification, whilst at B, the outside diameter should be made to the low end of specification to be steel-safe (Courtesy MPIF)

was made to nominal for all three axes, at best you will have only one axis where the finished sintered part will be centred on its nominal desired

so process stability is usually not the problem. However, optimisation of all dimensions on a part is likely to require tool modifications. This

“One direct effect of non-isotropic shrinkage is to make cylindrical geometries a challenge to manufacture competitively in MIM. dimension. The other two dimensions will not be centred on their nominal (either higher or lower) and this will degrade dimensional capability, especially when calculating Cpks. The good news is that the suboptimal result is typically very repeatable in parts that are gated and moulded in the same orientation,

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issue must be understood for tightly toleranced components requiring statistical process control. One direct effect of non-isotropic shrinkage is to make cylindrical geometries a challenge to manufacture competitively in MIM. The differing shrinkage rates (usually with a maximum and minimum at

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When initially sampling a MIM component, do not be surprised if, after sintering, the part is not centred on desired nominal dimensional values, whether due to non-isotropic shrinkage or other issues. If statistical dimensional control requirements have a strict application of a high (e.g. > 1.33) Cpk value, then any dimension not centred on the nominal will have difficulty in meeting this specification. Often a change in the tooling is the only option to adjust these dimensions in the finished parts. A change in the tooling will require either adding or removing material. If you need to add material to the mould it is sometimes possible to have the dimension fixed by plating. There are multiple concerns such as achieving a uniform plating, ensuring that the plating adheres strongly to the underlying metal and selecting only certain characteristics to be plated. Most often, adding material to an existing mould cavity is done by welding steel into the mould cavity. Given the small size of most MIM parts, the welding process is typically Micro-TIG or laser welding. After material is added, these added ‘gobs’ of steel need final machining, often by EDM. Concerns with welding include damaging the underlying or adjacent cavity steel and ultimately longterm adherence of the weld to the underlying metal. Requiring a welding step adds time and expense to the

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tool adjustment. If all else fails, remaking part or all of the cavity is the last-ditch option. This entails long lead times and high cost. So, modifying a tool where you need to add material is always a pain. It is always easier to remove material in a tool than to add it. In the design stage, the part model should be reviewed to identify where critical dimensions may need optimisation to ensure that they process to nominal. Internal features, such as diameters and slots, should be made to the ‘high’ side of the specification, while outside dimensions, such as the part length or outside diameters, should be made to the low side. The part in Fig. 7 illustrates this well. The part needs a final internal diameter of 10 mm +/- 0.04 mm, which will be made by a pin in the tool. Total tolerance span is 9.96–10.04 mm. The expected shrink factor is 20%, so a nominal tool size would be 10.00 x 1.2 = 12.00 mm. However, if the MIM process makes the part oval, the functional diameter will be less than the nominal 10.00 mm desired result. The solution is to make the pin in the tool target the high end of the specification. In this case a finished 10.03 mm diameter is at the ‘high’ end of the spec, but still within the specification, so make the pin in the tooling 10.03 x 1.2 = 12.036 mm.

6

Consider inspection and verification requirements during the design phase There is no doubt that the revolutionary development of 3D CAD modelling has made the design of complex parts easier. When combined with MIM’s design capabilities, the ability to create complex geometries, with features such as blended surfaces for a visually appealing and functional component, is useful and commonplace. As an example, the curved finger surface on the trigger in Fig. 8 has a radius that changes constantly from tip to base. While it is easy to create

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Ten rules for MIM success

A Fig. 8 In this award winning MIM firearms part from Parmatech Corporation, the trigger radius (A) constantly changes from tip to base. The ease with which MIM can achieve such features allows the design of both visually appealing and functional components; however the quality inspection methods for such surfaces can be challenging (Courtesy MPIF)

this type of surface, it is a lot more difficult to inspect the same surface and this creates quality control issues. Consider: • What method will be used to inspect? Comparator overlay? Optical inspection coupled with CAD analysis? Do these methods have sufficient precision to meet required statistical analysis? • Do both parties have the same inspection capability? Can results between the part maker and part purchaser be correlated? • Are there reliable datum points on the part to precisely locate the part for inspection? • What will the inspection time be per part? What is the sampling plan? Can the inspection be done economically?

The time to discuss these issues is before the project starts. Many designers are unaware that their component has attributes which will create inspection difficulties. Often, these difficult-to-inspect requirements are not critical to part performance and so mutually acceptable requirements can be established before complications arise. Addressing these issues at first-article submission is poor timing for all sides.

7

Do not ignore the need for parting lines, ejector pins and gates All engineers with experience in moulding technologies, whether plastic, die casting or MIM, realise that to convey material through the tooling to create a part you need to:

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MIM design rules

Fig. 9 It is essential to consider the need for parting lines, ejector pins and gates at an early stage. In these award winning parts by Indo-MIM Pvt. Ltd, the ejector pin locations are clearly visible and their location will have been agreed in advance with the client. Note that logos and text can be efficiently incorporated into a part by MIM (Courtesy MPIF)

• Introduce the material into the die cavity through a gate(s) • Remember that the tool needs to open, which creates parting lines where different sections of the tool contact each other • Remember that the part needs to be ejected, pushed out by ejector pins/blades/etc. Gate location, ejector locations and parting lines can all have a major effect on part quality, tool cost and tool life. It is essential - but easily overlooked - to reach agreement up front on these requirements, from all parties involved in the tool and part design (Fig. 9). There will be competing points of view from the different parties. For example, often the easiest way to create tooling will put the gate or parting line on a critical surface. If this creates variation unacceptable for the part function, the alternative may be putting in a slide or other tool element that drives the tool cost

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higher, lead-time longer, etc. For these issues to be avoided: • The designer must communicate what part surfaces are critical • The tool maker must communicate how they plan to create the tool cavities • The MIM part producer must bridge the concerns of designer and tool maker while ensuring the result will be a reliable tool that maximises productivity and repeatability.

8

Acknowledge that nothing good happens during MIM part shrinkage There is an old saying, applicable when someone does something illadvised late in the evening: “Nothing good ever happened after midnight.” A similar truism can be made with the MIM process; “Nothing good ever happens during shrinkage.”

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With few exceptions, the volume occupied by any molten material will decrease as it solidifies. This is a good thing for moulding technologies such as metal die casting and plastic injection moulding, as the decrease in volume frees the part to be ejected upon solidification. The shrinkage seen in these technologies is typically in the 0.5%-1.5% range, with some exceptions. In MIM processing, the shrinkage is much larger (Fig. 10) and there are a few stages to component shrinkage: Moulding shrinkage A MIM part will shrink from the tool cavity dimensions to the as-moulded part. The action is similar to what is seen in a plastic moulded part, but in MIM processing the shrinkage is relatively low, in the 0.3%-0.5% range. Variation in shrinkage can affect final dimensions, especially if there is poor melt temperature control during moulding, but it is typically a minor factor in overall dimensional variation.

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Debinding shrinkage This is also a minor contributor to overall shrinkage and, in certain feedstock systems, will result in dimensional growth rather than shrinkage. Variation in this step is typically minor. Sintering shrinkage The dominant factor in MIM shrinkage from mould cavity dimensions to finished part is in sintering, as the relatively low-density moulded part (for example, 5.0 g/cm3 is not unusual for steel MIM feedstock) densifies to a high-density (> 7.5 g/cm3 typical) sintered component. This can lead to a 15-20% linear shrink, which is much more shrinkage than in most other mould or cast technologies. While MIM shrinkage is repeatable in a well-maintained process, it must be recognised that it will increase part variation. Typically, the larger the dimension, the higher the likelihood that issues can arise such as drag on ceramic furnace trays, part warpage or gravity effects. These are common occurrences and need to be acknowledged as possible variables early in the product development cycle.

9

Choose a material which can be coined

For complex parts, it is safe to assume that there will be some level of warpage or distortion during the MIM process, as the part shrinks

Fig. 10 Demonstrating shrinkage in MIM: the part at the rear is as-moulded, whilst the parts at the front are after sintering (Courtesy Sintex a/s)

is commonly referred to as coining and is very prevalent within the MIM industry. Fig. 11 shows an awardwinning part that required coining to correctly realign its ‘U’ feature after distortion in sintering. A requirement in coining is that the yield strength of the material is exceeded during the operation. If the applied force during coining does not

“For complex parts, it is safe to assume that there will be some level of warpage or distortion during the MIM process, as the part shrinks 15-20% from its moulded to its sintered state.” 15-20% from its moulded to its sintered state. One way to correct distortion is by physically moving the part back into the original, nondistorted geometry. This operation

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significantly exceed the material yield strength, then the part will exhibit elastic spring back and do its best to return to its sintered dimensions. One way to minimise springback

variation is to choose the alloy with the lowest as-sintered yield strength that will meet component material requirements. For example, 316L and 17-4PH are common MIM alloys and both are effective corrosion-resistant stainless steels. If the application has relatively low requirements for strength and hardness, then choosing 316L makes sense because of its much lower sintered yield strength. If coined, it will retain the desired shape much better than 17-4 PH.

10

Consider mould filling integrity during part design One way to grow the available MIM market is to expand the design envelope for MIM applications. As much as you want to take on more challenging parts, care must be taken to ensure the part can be moulded

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first time. As this article highlights, designers need to consider the basics of ‘Design for MIM’, just as they need to consider ‘Design for Additive Manufacturing’ before adopting AM; the same goes for any manufacturing process. If there is one clear message to take from this article it is that for the smoothest MIM journey, speak with a MIM part producer as soon as you recognise that your part is a candidate for MIM. Time spent discussing the issues raised here at the beginning will save time and money over the lifetime of your part, and open up design ideas that you may never have previously considered.

Author

Fig. 11 This MPIF award winning lock hood manufactured by ARCMIM required coining after sintering to restore its original moulded configuration (Courtesy MPIF)

with sufficient material integrity. Attributes that can cause moulding or processing problems include: Thin sections Many MIM feedstocks will fill sections as thin as 0.3 mm, but the longer the distance to fill, the bigger the challenge will be. Non-fills can be an issue. Weld lines These occur where separate material flow fronts meet during moulding (e.g. material flowing around a pin) and can result in degraded strength and surface finish. Internal sharp corners These will always raise stress and can lead to cracking and lower strength properties, so introducing radii (minimum 0.1 mm radius preferred) in the tool will help greatly in reducing risk.

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Proper venting When the mould cavity is being filled with molten feedstock, the entrapped air in the cavity will build in pressure and needs to escape to enable the material to fill the cavity completely. Vents, which can be as thin as 0.01 mm, will allow air to escape while being tight enough to prevent flash formation in the vent.

Conclusion Whilst MIM components are all around us in our everyday lives, from smartwatch cases to household lock mechanisms, and automotive components to life-saving surgical devices, design engineers typically receive little or no exposure to the technology during their education and training. As a result, there is often a steep learning curve for those looking to implement this technology for the

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Matt Bulger Hudson, Ohio USA Email: atpmconsulting@gmail.com Matt Bulger, formerly President and General Manager of NetShape Technologies’ MIM division, has more than twenty-six years of experience in the fields of MIM and PM. Today he is an independent consultant for all metal powderbased technologies. He is an active supporter of the industry through his work with the Metal Powder Industries Federation (MPIF) where, amongst other positions, he served as President of the Metal Injection Molding Association (MIMA) and Chairman of MIMA’s Standards Committee. In addition to his role as a consultant, he serves as Administrative Director for the Association for Metal Additive Manufacturing (AMAM).

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ABSTRACT SUBMISSION DEADLINE: SEPTEMBER 30, 2018

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International Conference on Injection Molding of Metals, Ceramics and Carbides February 25–27, 2019 • Orlando, FL

CALL FOR PRESENTATIONS MANUFACTURING INNOVATIONS: • Part design • Tooling • Molding • Debinding • Sintering MATERIALS ADVANCEMENTS: • Metals & alloys • Ceramics • Hardmaterials TARGETED AUDIENCE: • Product designers • Engineers • End users • Manufacturers • Researchers • Educators • Students

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The second Arburg PIM conference

The future of Powder Injection Moulding: Innovations and opportunities at Arburg’s second PIM conference Earlier this summer PIM industry leaders from around the world came together in Lossburg, Germany, for Arburg GmbH + Co KG’s second International PIM conference. The event, which took place five years after the company’s inaugural PIM conference, had the goal of exploring the future of metal and ceramic injection moulding through two days of presentations by parts manufacturers, materials suppliers, equipment producers and researchers. Dr Georg Schlieper reports on the event for PIM International.

Global and regional PIM markets Several speakers presented their estimates for market data for the global PIM industry. According to Professor Randall M German, San Diego State University, California, USA, the total sales value of PIM products exceeded $2.5 billion in

2017 (Fig. 1), with an annual growth rate of 12%. The Asian PIM industry, led by China, is by far the strongest, generating about two-thirds of the world’s MIM parts production. Europe has a market share of about 20% and the US about 15%. The Asian market is driven mainly by the consumer electronics sector, whereas the European market is widely based on

2800

Sales by key countries/regions

2400

Annual sales (million $)

The second Arburg PIM Conference took place at Arburg’s Customer Care Centre in Lossburg, Germany, on June 5–6, 2018. This international event focused on the future potential of Metal and Ceramic Injection Moulding technology and was attended by around 200 participants from twenty-three countries. As with the first Arburg PIM conference, held in 2013, invited delegates gathered to exchange news on the latest application developments along with fresh perspectives on production processes, materials and equipment. Over the two-day event, eighteen presentations were made by experts from research and industry alike, addressing various aspects of the future of PIM technology. In addition to these high-level presentations, delegates could see the injection moulding of various groundbreaking MIM and CIM components, such as smartphone casings, turbine wheels and LED heat sinks. A number of social events provided the opportunity for networking with fellow guests.

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PIM

2000

(includes metals, ceramics and carbides)

1600 1200 800

MIM

400 0

1985

1990

1995

2000

2005

2010

2016

China

$910 m

Europe

$426 m

USA

$310 m

Taiwan

$230 m

India

$150 m

Japan

$103 m

Korea

$80 m

Singapore

$52 m

2020

Fig. 1 Estimated global MIM and PIM sales (Courtesy Prof R M German)

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The second Arburg PIM conference

Fig. 2 Gerhard Böhm, Sales Managing Director at Arburg, welcoming participants to the 2nd Arburg PIM conference (Courtesy Arburg)

automotive and consumer products. In the US, firearm components play a key role in the MIM industry. The size of the Ceramic Injection Moulding sector is roughly 15% of the global PIM market. MIM in North America Jim Neill, CM Furnaces, and Scott Robinson, Centorr Vacuum Industries, took a closer look at the MIM market

K Johnson, Contributing Editor. The article referred to input and interviews with sixteen industry experts representing consultants, metal powder suppliers, equipment makers, service companies and MIM part manufacturers in the USA. The speakers estimated a sales volume of MIM parts in North America amounting to $367–420 million and an annual growth rate of 5%. Note

“The speakers estimated a sales volume of MIM parts in North America amounting to $367–420 million and an annual growth rate of 5%.” based on data taken from an article published in the March 2018 issue of the International Journal of Powder Metallurgy, written by Peter

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that the North American figures refer only to the Metal Injection Moulding industry and do not include ceramics.

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MIM in Europe Lionel Aboussouan, Executive Director of the European Powder Metallurgy Association (EPMA), presented market data on both the MIM and PM industries. The annual turnover of the European MIM industry was estimated at €410 million ($475 million) and the world market at $2.58 billion. Aboussouan highlighted that, whilst the European MIM market is dominated by automotive and consumer products, mechanical engineering and medical applications are also important (Fig. 3). PIM in Asia A comprehensive and detailed overview of the Asian PIM industry was given by Prof Peng Yu, Associate Professor at the Department of Materials Science and Engineering, Southern University of Science and Technology, Shenzhen, China. Yu put the annual sales of the Chinese MIM industry in 2017 at $853 million. Two

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thirds of Chinese MIM production goes into cell phones, while the remainder is relatively evenly distributed among the common MIM applications such as automotive, consumer, tools and medical (Fig. 4). Japan suffered six years of declining MIM production between 2010 and 2016, but recovered in 2017 to an estimated $100 million in MIM market revenues, with an expected growth rate of 5-6%. The Japanese MIM market is primarily based on industrial machinery, medical and automotive applications. India’s PIM industry tripled its revenues from $50 to $150 million between 2014 and 2016, with most of its products exported to North America, Europe and Japan. Other important suppliers of PIM products are South Korea ($80 million) and Singapore ($52 million). Asia’s MIM industry is expected to continue to experience strong growth, particularly in the automotive and medical markets.

Computer simulation of PIM processes One method for the further advancement of PIM technology is the widespread use of computer simulation software for the injection moulding process, as highlighted by Götz Hartmann of MAGMA, the company behind Sigmasoft PIM simulation software. Although computer simulation in plastic injection moulding technology is today widespread, there is still a lot of catching up to do in relation to Powder Injection Moulding. One reason for this is that thermoplastic materials and PIM feedstocks show significantly different flow behaviour and computer models therefore require special adaptations for PIM feedstocks. Hartmann assured participants that today’s computer models are very reliable in describing the actual processes involved in the injection moulding of PIM feedstock and can therefore save time and money when it comes to tool design. The effect of wall friction on powder-binder segregation has been

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The second Arburg PIM conference

Consumer 24%

Automotive 43%

Mechanical engineering 17%

IT 4% Medical 12%

Fig. 3 MIM market segments in Europe (Courtesy EPMA)

Automotive 7% Cell phones 66%

Consumer 7%

Computers 5% Tools 6% Medical 4% Others 5% Fig. 4 MIM market segments in China (Courtesy Peng Yu)

studied in capillary rheometer tests. Unlike thermoplastics, whose flow behaviour is referred to as ‘fountain flow’, a flow behaviour known as ‘jet flow’ often occurs in PIM feedstocks. In places where the cross-section of the cavity increases, jetting may take place associated with a segregation of binder and powder. These phenomena can now be realistically represented by computer models.

Modelling the flow of PIM feedstocks can help to detect possible moulding defects at the beginning of tool design and correct them prior to the actual mould manufacture and also to improve mould filling. Hartmann gave other examples of computer modelling of PIM processes. He outlined that the thermal balance of the mould and the heat flow within the mould

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Temperature °C 170 165 160 155 150 145 140 135 130 125 120 115 110 105

Temperature development of the mould, one cycle at a stable process, Variotherm 165°C / 120°C

100

Fig. 5 Computer modelling of the mould temperature (Courtesy MAGMA) 90% -10 µm

Injection Moulding Pressure (MPa)

90 80

70 59 Vol% 60

56 Vol% 59 Vol%

90% -10 µm

90% -22 µm

90% -10 µm

90% -22 µm

-32 µm

90% -22 µm

-32 µm

-32 µm 62 Vol %

65 vol %

62 Vol 50 % Solid Loading 65 vol %

62 Vol % 40% Solid Loading 65 vol

ding

30

-32 µm

20 10 0

1200

56 Vol%

59 Vol%

62 Vol %

65 vol %

Solid Loading

Fig. 6 Injection moulding pressures for 17-4PH powders (Courtesy Catamold Sandvik Osprey)

1000 800

1200

600

0

20

Die pressure (Bar)

200

New EVO feedstock evo Catamold

Catamold

Traditional POM-based feedstock

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Catamold 60 80 evo

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Speed (cm3/s)

100

(cm3/s)

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100 200 0

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40

60

Injection speed (cm3/s)

80

100

Fig. 7 The reduced moulding pressure required for Catamold evo (Courtesy BASF)

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is of prime importance for efficient injection moulding. The computer model must cover all heat-relevant parts of the mould, including their thermophysical properties and the heat transfer between neighbouring parts. Fig. 5 shows four temperature images of a mould during one cycle for Variotherm, an innovative mould tempering technology. The temperature profile in the sintering furnace has also been modelled, and a study showed that the arrangement of the parts on the trays has a significant influence on the temperature uniformity in the furnace. A so-called ‘military’ arrangement in straight rows allows a more effective radiation heat exchange among heating elements and parts compared to a chaotic or random arrangement, designated as ‘guerilla style’. This leads to a much more efficient heat exchange within the furnace, and consequently supports a more uniform temperature in the furnace load. The effect of various heating rates and the orientation of the parts in relation to the heat source on temperature gradients in the 90% -10load µm has also been studied furnace 90% -22 µm by computer simulation.

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Innovation in powders and feedstocks for PIM 17-4PH: particle size vs. processability The availability and cost of raw materials is a substantial part of the total manufacturing cost for PIM parts and can therefore be expected to play a key role in the future of the technology. For metal Catamold powders, particle size is a major cost factor, with fine powders being more expensive than coarse powders. Keith Murray Catamold evo of Sandvik Osprey, Neath, UK, a leading supplier of gas atomised metal powders, presented a study on the effect of the particle size of 17-4PH, one of the most widely-used MIM alloys, on processing and final properties. Gas atomised powders exhibit spherical particle shapes

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The second Arburg PIM conference

Fig. 8 Various MIM and CIM parts were injection moulded in the conference’s display area during conference breaks, including these bionically optimised MIM heat sinks for LED lights, manufactured from Catamold 316L (Courtesy Arburg)

and excel in flow characteristics, low impurity levels and high tap densities. The study compared three gas atomised grades with particle sizes 90%-10 µm (D50 = 5.4 µm), 90%-22 µm (D50 = 10.3 µm) and -32 µm (D50 = 13.5 µm). Feedstocks with various solid loadings from 56– 65 vol.% were prepared with a polyoxymethylene (POM) based binder. The plot of injection moulding pressure versus solid loading (Fig. 6) shows that grade 90%- 22 µm offers the best mouldability at solid loadings up to 62 vol.%. At higher solid loadings, not only does the moulding pressure increase, but porosity was also higher and coarser after sintering at 1350°C. The best results were achieved with the 90%-22 µm grade with a solid loading of 62 vol.% and sintered at 1350°C. Catamold evo: the next generation BASF’s Johanna Wallot presented information on the ‘next generation’

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of POM based feedstock, offering improved mouldability and marketed under the trade name Catamold evo. The suffix ‘evo’, it was stated, stands for evolution and is intended to represent both

The evolution of CIM feedstocks A review of the challenges of ceramic feedstocks was provided by Karin Hajek of Inmatec Technologies GmbH, Rheinbach, Germany, a manufacturer of

“The expertise of the feedstock manufacturer lies in processing the ceramic powders into a homogeneous powder-binder mixture, destroying agglomerates and producing granulates of homogeneous shape and size...” the continuity of the original binder concept and a progression towards new applications. The die pressure required for the new feedstock demonstrates the improvement it offers in moulding characteristics (Fig. 7).

ready-to-use CIM feedstocks. Hajek highlighted the importance of identifying the right ceramic powder grades for demanding engineering applications that do not exceed given cost limitations. The expertise of the feedstock

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The second Arburg PIM conference

Mould insert

TCU

Liquid hot runner

TCU

Outlet

Outlet

Inlet

Inlet

Vario Consumer Energy Battery

Fig. 9 Schematic of test mould for a mobile phone back cover (top left) and dynamic temperature control system (top right). Lower images show a smartphone back cover in the green state (left) and as-sintered (right) with achieved tolerances (Courtesy Arburg)

manufacturer lies in processing the ceramic powders into a homogeneous powder-binder mixture, destroying agglomerates and producing granulates of homogeneous shape and size for even dosage. The feedstocks should exhibit high flowability and be completely free from metallic contamination. Inmatec offers three standard types of binder system; one is based on wax-polymer and suitable for partial debinding in water; another, based on polyamide, requires partial debinding in acetone; and the third is based on POM and requires catalytic debinding in a nitric acid environment. Customised ceramic powders and binder formulations are also developed.

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Innovation in production technology Extending the size range of PIM parts Arburg, the conference host, was represented in a presentation by Hartmut Walcher, a member of Arburgâ&#x20AC;&#x2122;s PIM Team. Walcher analysed the injection moulding process and developed ideas on how to extend the limits of component size, to reduce wall thickness and to improve the dimensional stability of PIM products. An innovative system for dynamic mould temperature control was identified as a major step towards improved flow length and dimensional stability. Traditionally, injection moulding machines are equipped with a single temperature control unit (TCU), which maintains the mould temperature at

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a level that freezes the feedstock to allow the component to be removed. The new dynamic temperature control enables two temperature levels: a higher one for the injection phase and a lower one for the cooling phase. The higher temperature in the injection phase facilitates the flow of the feedstock. A test mould was built for a smartphone back cover and operated with a dynamic temperature control system (Fig. 9, top). The dynamic temperature control is composed of two TCUs, one supplying hot water for the high temperature and one supplying cooler water for the lower temperature. The switch-over unit (Vario) directs the water to the mould (Consumer) as required. The energy

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The second Arburg PIM conference

Fig. 10 Turbocharger adjusting lever and pin made by 2C-MIM. The parts combine weldable stainless steel and a wearresistant cobalt alloy (Courtesy Schunk Sintermetalltechnik)

storage unit (Battery) serves to save energy through intermediate storage of hot or cooler water. The smartphone back cover (Fig. 9, bottom) had green part dimensions of 160 x 81 mm and a wall thickness of 1–1.2 mm. The projected area was 128 cm² and the shot volume amounted to approximately 19 cm³. The runner length was 21 mm and the maximum flow length in the mould was 47 mm, with an aspect ratio of 47. With a traditional temperature control it would have been impossible to mould this part, but flawless parts could be moulded using the dynamic temperature control system. The width of the sintered part had dimensional variations of less than +/- 0.2 mm (0.2%) and the length varied by less than +/- 0.2 mm (0.1%). The sintered density was 7.68 g/cm³; 98.3% of the theoretical density. Walcher summarised the benefits of dynamic temperature control as enabling long flow lengths, preventing powder-binder segregation and achieving a uniform green density. Consequently, shrinkage during sintering is more uniform and closer tolerances can be met. The sintered density was high enough for polishing without subsequent HIP treatment.

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Extrusion and Additive Manufacturing using PIM feedstocks PIM feedstocks are not only suitable for injection moulding, but also for extrusion and Additive Manufacturing. Therefore, some speakers included these technologies in their considerations on the future of PIM technology. Prof Dr Frank Petzoldt, from Fraunhofer IFAM, Bremen, Germany, stated that he expects many new products to be made using PIM feedstock extrusion. The process is able to generate complex profiles in a range of materials with very thin wall thicknesses. The research group DYPAM, led by Prof Gemma Herranz of Universidad de Castilla La Mancha (UCLM), Ciudad Real, Spain, has developed a strong, flexible filament based on a proprietary new binder formulation that can be coiled and printed like plastics on low cost Additive Manufacturing machines. The resulting green parts are comparable to injection moulded parts and the debinding and sintering steps are identical. This technology, called Fused Filament Fabrication (FFF), is being evaluated for the production of prototypes and small series of PIM parts, as well as for new AM designs.

Two-component MIM now a reality Michael Guenther, Schunk Sintermetalltechnik, Germany, presenting on behalf of Ingolf Langer, reviewed Schunk’s first two-component (2C-MIM) products. In this process, two different feedstocks are co-injected into a mould followed by sintering to form a two-material component with a strong join. The components presented are used in a turbocharger with a variable turbine geometry (Fig. 10). The pin must be weldable and have a wear and corrosion resistant surface, and the adjusting lever must also be corrosion resistant and not wear at the point of contact with the pin. The solution developed by Schunk was two MIM parts combining weldable stainless steel and a wear-resistant cobalt alloy. Before these parts could be produced in large numbers at high quality, numerous problems had to be solved. Several feedstock variations with different binders and powders were tested. The runners of the different materials had to be separated, the cycle times were increased and a common sintering regime had to be found for both alloys to produce parts with high densities and uniform shrinkage.

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Fig. 11 The injection moulding and co-sintering of two material components not only eliminates the joining process step but also opens new perspectives for adding functional properties to MIM parts. The image on the left shows joining using sequential injection moulding, whilst the image on the right is as a result of simultaneous injection moulding (Courtesy IFAM)

of the exhaust gases takes place in a two-stage Red-Ox process with the option of reducing NOx as well. A heat treatment unit can also be integrated between the hightemperature zone and the cooling zone. Cremer reported that the worldwide installed MIM-Master capacity is currently 3,500 t/a in Europe (18 units), 1,500 t/a in the Americas (8 units) and 7,200 t/a in Asia (41 units). Cremer’s ambition for 2020 is to be able to double capacity on the same floor space as today’s machines and reduce energy consumption figures to 75% of today’s values. The higher loading of the furnace will be enabled with a new integrated temperature control system on multiple levels and a modified furnace design for optimised laminar gas flow based on computer simulation.

Advanced PIM products and applications Fig. 12 Demonstration fuel injector valve sleeve made of two materials (Courtesy IFAM)

Guenther imagines more useful material combinations for multi-component MIM in the future. Combinations such as soft magnetic/ wear resistant, soft magnetic/nonmagnetic, weldable/wear resistant, wear resistant/heat resistant, low cost/high cost and metal/ceramic, were proposed. Fraunhofer’s Prof Dr Petzoldt identified a trend towards larger and heavier MIM parts and also believes that 2C-MIM is gaining increasing significance. The valve sleeve shown in Figs. 11-12 combines magnetic and non-magnetic stainless steel in a single component. This part is approximately 40 mm long, 6 mm diameter and has a wall thickness of just 0.65 mm. Advances in furnace technology The current status and plans for the future of high-temperature furnace technology for the mass production

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of MIM parts were highlighted by Ingo Cremer, Managing Director of CREMER Thermoprozessanlagen GmbH, Düren, Germany. The company’s original MIM-Master continuous debinding and sintering furnace has since evolved into a whole family of walking-beam furnaces with different production capacities, ranging from an estimated annual capacity of 72 tons to more than 400 tons of ferrous feedstock. In addition to the single-line models, twin-runner walking-beam furnaces are also available. Debinding can be carried out both catalytically and with solvents. According to Cremer, the latest versions of the MIM-Master are characterised by improved ventilation and more accurate temperature control. Gas and energy consumption have been reduced and furnaces can handle larger and heavier components. The post-combustion

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Aerospace: MIM can fly! In addition to ongoing improvements in productivity, materials and equipment, a key future task for the PIM industry is to improve on existing applications and develop new ones. Jean-Claude Bihr, General Manager of Alliance-MIM, Saint Vit, France, sees a growing demand for MIM parts in the aerospace industry, both in civil and military aircraft. Aerospace applications require a long time for development and qualification, but this is rewarded by long life cycles and viable revenues. Potential aerospace applications are injectors and a swirler in the combustion chamber, turbine and compressor blades and vanes, outer shrouds, mechanical parts, connectors and more. Elevated temperature applications require nickel base alloys such as Hastelloy X, Rene 77 and INCO 718. Where weight reduction is important and lower temperatures prevail, titanium alloy Ti6Al4V may be used, and mechanical parts and connectors are usually made of 17-4PH stainless steel.

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The second Arburg PIM conference

The swirler shown in Fig. 13 is made of Hastelloy X. Hot Isostatic Pressing (HIP) is performed after sintering to remove the residual porosity. The MIM process achieves an isotropic microstructure free from residual stresses and a surface roughness Ra of less than 2 µm without secondary machining. Schunk agreed with Alliance-MIM that the aerospace sector has great potential for MIM applications. Guenther presented the compressor vane shown in Fig. 14 as an example. This component, with a height of approximately 40 mm, is made from the nickel base alloy Inconel 713LC and entered commercial production earlier this year for Rolls-Royce. Opportunities in the dental sector Looking at innovation in the orthodontic sector, Michael Wei, CEO of MEM Dental Technology, Taiwan, reported on the future of MIM materials for dental brackets. The company’s first MIM dental brackets were made from 316L austenitic stainless steel. The next step was the Co28Cr6Mo alloy ASTM-F75. The first ceramic brackets made from zirconia and alumina were produced in 2014, shortly followed by titanium Ti6Al4V. Ongoing research is directed at a second-generation zirconia, porous NiTi alloy, niobium and magnesium alloy. CIM materials and processing innovations In the Ceramic Injection Moulding sector, representing around 15% of the PIM industry worldwide, alumina and zirconia are still the most widely used materials. Moritz von Witzleben, General Manager of Inmatec Technologies GmbH, reported that the demand for zirconia CIM products is currently growing significantly in the consumer electronics market, whilst there are an increasing number of applications for alumina in the automotive sector and the consumer products market. A growing demand is also being seen for silicon nitride and translucent ceramics. Other engineering ceramics such as

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Fig. 13 This swirler is designed for use in the combustion chamber of an aircraft engine and uses green machining to create the very small holes and sinter joining to create an assembly of multiple green parts (Courtesy Alliance- MIM)

Fig. 14 Compressor vane of an aircraft engine. This part is approximately 40 mm tall and is made from the nickel base alloy Inconel 713LC (Courtesy Schunk Sintermetalltechnik)

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Y-TZP is used for dental implants (Fig. 15), but many other applications are possible. The material is characterised by high mechanical strength and fracture toughness. The coated powder associated with CIM processing achieved a 20% higher strength than die pressed material. It was shown that CIM makes it possible to cost-effectively manufacture small, complex parts with high precision and excellent mechanical properties.

Fig. 15 Dental implant made from yttria-stabilised zirconia (Courtesy OxiMaTec)

silicon carbide and boron nitride are available, but it was stated that demand remains limited. Just like MIM, the CIM industry is also developing 2C-CIM products based on the co-injection of different feedstocks. The first ceramic-ceramic components have been developed and manufactured, but no ceramic-metal applications have yet been commercialised. Ceramic Additive Manufacturing using Fused Filament Fabrication is also under development and, according to von Witzleben, the potential of engineering ceramics manufactured by extrusion, CIM or AM is huge and still barely tapped. Yttria-stabilised zirconia (Y-TZP) for dental implants An insight into the development process for CIM materials was provided by Wolfgang Burger, General Manager of OxiMaTec, Hochdorf, Germany. The target was a biocompatible ceramic for dental implants. The material of choice was

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yttria-stabilised zirconia (Y-TZP) processed by CIM. Commercial powder grades of high chemical purity for die pressing are available from several suppliers, produced by co-precipitation of zirconia and yttria followed by calcining. The specific surface area of these powders was 7–9 m²/g, and the mean particle size D50 = 0.3-0.4 µm. OxiMaTec developed an alternative powder production process and coated the particles of extremely fine pure zirconia powder with yttria. This powder had a specific surface area of 17.5 m²/g and a mean particle size of D50 = 0.08-0.22 µm. The extremely fine powder required a modified binder formulation for plasticising, after which defect-free green parts could be produced by injection moulding. The sintering temperature to acheive full density was much lower than for the commercial powders and resulted in a superfine microstructure thanks to reduced grain growth.

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PIM materials used in energy generation and next generation vehicles The Solid Oxide Fuel Cell (SOFC) was presented as a potential application for ceramic and metallic components produced by the FFF of PIM feedstock by Dr Christina Berges, a member of the Design and Processing of Advanced Materials (DYPAM) consortium at Universidad de Castilla La Mancha, Ciudad Real, Spain. Whilst FFF enables the effective development of PIM prototypes, it was suggested that conversion to CIM for the mass production of SOFC ceramic anodes could provide a major boost to the industry. Furthermore, production of metallic interconnectors by MIM could improve the efficiency of SOFCs as well as expanding the MIM market within the energy sector. Prof Dr Petzoldt stated that he expects a growing number of so-called functional materials to be produced by PIM. Functional materials are characterised by specific properties that can be selectively influenced. They are distinguished from structural materials, but there is no clear differentiation; functional materials focus on the intended use, e.g. magnetic properties or thermal conductivity, not the structural design of components. Petzoldt envisaged neodymium-iron-boron permanent magnets of complex shape as an important potential PIM product. Magnetocaloric materials could also be applied for innovative cooling concepts.

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Fig. 16 Conference participants outside Arburg’s headquarters in Lossburg, Germany (Courtesy Arburg)

Conclusion The various contributions offered by international experts to the Arburg PIM Conference provided a diverse picture of the current state of the global PIM industry, whilst lively discussions highlighted opportunities for the development of new products. It is very unusual and highly appreciated that an industrial company such as Arburg should organise a conference of this size, providing the space and hosting the participants at its own expense

to further the industry in which it operates as a whole. It was clear from the conference that raw materials and equipment suppliers, researchers and parts manufacturers can all benefit by continuing to work hard for the future of their industry. In 1940, American computer science pioneer Alan Kay stated, “The best way to predict the future is to invent it.” It is hoped that, as with all innovative and forward-looking technologies, the efforts of all those involved in PIM technology will bear rich fruit.

Author Dr. Georg Schlieper Harscheidweg 89 D-45149 Essen Germany Tel: +49 201 71 20 98 Email: info@gammatec.com

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BASF Ultrafuse 316LX

Ultrafuse 316LX: BASF’s ‘Catamold® on a spool’ presents opportunities for MIM producers BASF SE’s Catamold® feedstock is synonymous with the high volume production of components by Metal Injection Moulding and the product’s launch, more than thirty years ago, was the catalyst for the industry’s global growth. Today, BASF has adapted this technology for metal Additive Manufacturing via Fused Filament Fabrication (FFF). This technology offers the company’s existing MIM customers a low-investment route into metal AM, whether for prototyping or the development of entirely new applications.

Through continued developments in materials, equipment, software, simulation and other process improvements, metal Additive Manufacturing is making a steady transition from a tool for prototyping to a manufacturing route capable of producing high value added metallic components. Considerable time and effort has been focused on the improvement of key AM metrics such as production rate, reliability and repeatability, without compromising the profound increases in part complexity and customisation that the technology offers. BASF, with several decades of experience in the development, production and optimisation of a range of materials for Metal Injection Moulding and metal feedstock extrusion, continues to advance the field of metal AM. The Ultrafuse 316LX metal composite filament is BASF’s entry point into metal AM materials, leveraging the metallic powders and binder formulations of the company’s Catamold® feedstock range, the most widely used in the MIM industry worldwide. From its AM application centre in Heidelberg, Germany, BASF

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provides a full spectrum of engineering, logistics and development services. These services encompass design for AM, AM training, and ready access to BASF’s worldwide network of debinding and sintering providers. Analogous to the injection moulding of Catamold feedstocks, Ultrafuse 316LX filament has

been developed to produce green parts using almost any Fused Filament Fabrication (FFF) Additive Manufacturing system. Once built, no additional post-processing steps are required prior to debinding and sintering [1]. Taking advantage of the reliability and high productivity of catalytic debinding, Ultrafuse

Fig. 1 Stainless steel feedstock on a spool will be an unusual sight for MIM producers, but BASF believes that this technology presents a number of opportunities for the industry

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BASF Ultrafuse 316LX

Filament properties Test method

Typical values

Filament diameter

Ø 1.75 mm

Ø 2.85 mm

Filament diameter tolerance

non-contact dimensional measurement

±75 µm

±75 µm

Roundness

non-contact dimensional measurement

±50 µm

±50 µm

radius gauge

5 mm (+/-1 mm)

10 mm (+/-3 mm)

Length per spool

Tactile length gauge

250 m

100 m

Weight per spool

Scale

3 kg

3 kg

Bending radius

Table 1 Preliminary filament properties

Ultrafuse 316LX recommended build parameters Nozzle temperature (C°)

210–235

Bed temperature (C°)

90–100

Nozzle diameter (mm)

0.4

Extrusion width (mm)

0.30–0.35

Layer height (mm)

0.15–0.25

Build speed (mm/sec)

20–35

Table 2 Recommended build parameters for BASF Ultrafuse 316LX

316LX enables the production of fully sintered 316L stainless steel components, making it an ideal material for companies that are already utilising catalytic debinding and sintering in their manufacturing operations. Ultrafuse 316LX users can easily step into and explore metal Additive Manufacturing and debind and sinter their parts - be they prototypes for MIM parts or new developments - alongside traditional MIM components, without the need for special furnace runs or equipment. All of the benefits intrinsic to catalytic debinding apply to Ultrafuse 316LX. Components created with Ultrafuse 316LX benefit from the ability of FFF to produce true hollow parts without the need for removal of powder residues from internal structures. Here, the radical reduction in part mass, when combined with topological optimisation and simulation tools, will enable Ultrafuse 316LX users to further optimise their individual products and systems.

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Part manufacture from Ultrafuse 316LX Successful and efficient Additive Manufacturing of parts from Ultrafuse 316LX, as with any manufacturing method, depends on the quality of the source material, the machine being used and the proper selection of process parameters. BASF, with its established Catamold supply chain, is uniquely positioned to provide the highest levels of material performance and quality. Before Ultrafuse 316LX is sent out to customers, key quality metrics such as diameter, circularity and metal load are first verified. From a safety perspective, the encapsulation of potentially harmful metallic powders in a thermoplastic binder system has important advantages compared to other AM processes. As the metal particles are uniformly distributed and immobilised in the binder matrix, the potential hazards of handling fine metallic powders are dramatically reduced compared to Powder Bed Fusion (PBF), Direct

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Metal Deposition (DMD) or Binder Jetting. Filamentation enables more convenient handling and machine cleaning when compared to powder bed or cartridge-based systems, thus eliminating the risk of powderrelated health and explosion hazard concerns. Ultrafuse 316LX is a composite material formulation of highly refined metal powders and thermoplastic binders suited to FFF Additive Manufacturing, catalytic debinding and sintering. At more than 80% metal content by weight, the feedstock provides both high metal content and high flexibility for optimised delivery via pulley or other delivery methods commonly used in a wide variety of FFF machine designs. Due to its high flexibility, the filament can be guided through complex idler pulleys, as well as guide roller filament transportation systems, and is currently available in both industry standard 1.75 mm and 2.85 mm diameters. Table 1 gives an overview of the filament’s properties. FFF machine requirements Having been designed from the start to work with any open FFF Additive Manufacturing platform, Ultrafuse 316LX has been proven to perform well on the full spectrum of currently available FFF machines, ranging from custom-built prototypes to high-end industry level machines. Any FFF machine capable of extruder temperatures around 230°C and equipped with a heated build platform can use Ultrafuse 316LX. It is also compatible with both Bowden and direct drive extruders through the use

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BASF Ultrafuse 316LX

Fig. 2 The metal sections of this gripper were manufactured from BASF’s Ultrafuse 316LX and effectively demonstrate the current capabilities of the technology

of a non-slip outer surface. Individual machine characteristics, such as nozzle diameter, extruder type and thermal characteristics, will affect part quality outcomes, and each user must determine which machine parameters are best suited for their individual platform’s configuration and part requirements. A fundamental requirement of all FFF AM operations is a level surface or build plate to which the material can adhere while allowing for removal once the build is complete. Once the machine bed has been levelled during set-up, the application of polyimide film has been proven to fulfill the adhesion and separation requirements and is recommended as the build plate surface. Preparing a part for FFF The movement, material extrusion and temperature instructions FFF machines rely on to create additively manufactured parts are encoded into a set of machine instructions referred to as a G-code. Analogous to traditional Computer Numeric

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Controlled (CNC) manufacturing equipment such as milling and turning machines, FFF machine G-codes are created via Computer Aided Manufacturing (CAM) software. Referred to as a Slicer, FFF CAM subdivides the target geometry of a 3D model into a set of 2D layers with successive layers combining to produce a part. A wide variety of slicers is currently available, ranging from free open source software to extensive commercial packages equipped with a wide variety of simulation, redesign and machine optimisation tools. Recommended build parameters The proper selection of FFF process parameters is critical to ensuring final geometric accuracy, surface quality, process stability and overall part quality. A slicer’s various settings, referred to as build parameters, produce a build operation which is then encoded into a G-code file containing the machine instructions to build the required part.

Although highly capable, slicers are not able to provide optimised build instructions for any conceivable part on any FFF machine and therefore require operator optimisation. To reduce the amount of testing required to get an Ultrafuse316LX customer building their first parts, the parameters seen in Table 2 have been developed to suit the widest range of user needs and should serve as a starting point for any new project.

Design considerations A great part begins with a great design. To enable the highest possible quality and performance, Ultrafuse 316LX parts should be designed to exploit the advantages and avoid the limitations of FFF, debinding and sintering (Fig. 2). To enable further enhancements in part quality and performance, the following sections provide guidance for Ultrafuse 316LX users throughout part design, building and post-processing operations.

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BASF Ultrafuse 316LX

with geometry and build strategies, general shrinkage guidelines under typical building operations are shown in Table 3. As a part shrinks during densification, friction between the part’s base and the sintering substrate may cause distortion or warpage of a part’s shape. Ceramic powders commonly used in MIM and other sintering operations have been shown to reduce friction and thus mitigate this friction induced warpage.

Fig. 3 Extrusion width example; wall 1.05 mm extrusion width (left 0.35 mm) (right 0.40 mm), demonstrating the effect that wall thickness and extrusion width combinations can have on fill density Ultrafuse 316LX shrinkage after debinding and sintering X axis shrinkage

16.5%

Y axis shrinkage

16.5%

Z axis shrinkage

20.5%

Table 3 Typical shrinkage of Ultrafuse 316LX upon debinding and sintering

Part size FFF processed Ultrafuse 316LX has routinely produced parts in the single kilogram range. Conversely, in typical MIM operations, parts over 100 g are rarely considered feasible due to economic constraints. FFF Ultrafuse 316LX part sizes are limited by the size of the build chamber and the debinding and sintering furnaces used. Parts sizes up to 100 mm in the X and Y directions have proven to be generally achievable. A debound but unsintered part has the lowest structural integrity and therefore overhanging or undercut structures usually require support structures. To minimise the chances of structural collapse, height-to-width ratios no greater than 3 to 1 have proven to be most effective. Tolerances Typical FFF machines provide dimensional accuracies on the order of an extrusion width in the X-Y build

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plane. For example, an overall dimensional accuracy in X and Y is typically around ± 0.35 mm for an extrusion width of 0.35 mm. Build layer height is directly related to the accuracy and level of feature fidelity achievable and therefore must be accounted for in the orientation of the part on the build plate. The relation between layer height and dimensional accuracy is most pronounced for circularity. Circular features are best produced when the axis of rotation is perpendicular to the build direction. Shrinkage As individual metal particles coalesce into a solid mass, a reduction of part size occurs, and this is referred to as shrinkage. As with traditional MIM parts, oversizing factors are applied during the design stage to compensate for shrinkage during sintering. Although exact shrinkage values can vary

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Wall thickness and transitions Wall thicknesses between 1-8 mm have proven to be most consistently produced while allowing for rapid debinding. Extrusion width has a critical effect on the ability to produce stable walls. The preferred situation is a wall thickness that is a multiple of the extrusion width. Regrettably, many slicers focus primarily on a part’s outer surfaces, followed by infill. When the extrusion width and wall thickness do not match, inner portions can be left either with no infill or with partial infill, resulting in lowered density and thus reduced structural integrity. The different slicer results shown in Fig. 3 demonstrate the effect improper wall thickness and extrusion width combinations have on the fill density of features. The hexagonal sections shown have a wall thickness of 1.05 mm. At an extrusion width of 0.35 mm (left) three full extrusion widths are used to create the wall structures. Conversely, with an extrusion width of 0.40 mm (right), the slicer is forced to fill the gap between the outer surfaces with partial movements resulting in decreased mechanical properties. Thermal stresses have been found to cause delamination or cracking and may be amplified by notches or abrupt cross-sectional changes. The addition of fillets or chamfers has been shown to reduce part cracking and layer delamination during debinding and sintering. If part geometry constraints limit redesign, build orientation can often be adapted to reduce geometric distortion.

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BASF Ultrafuse 316LX

600

60%

500

50% Elongation at Break [%]

Tensile Strength [Mpa]

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400 300 200

100 0

UTS

MIM 510

FFF - XY 498

40% 30% 20%

10% 0%

FFF - Z 414

EL%

Fig. 4 Tensile strengths of MIM and Ultrafuse 316LX test specimens after debinding and sintering

Mechanical properties Sintered material tensile strength data are shown in Figs. 4-5. Ultrafuse 316LX shows an ultimate tensile strength of 498 MPa in the XY direction, with an elongation of 43%.

Green part post-processing For component features requiring high tolerances, CNC milling or grinding have routinely been utilised in both the green and sintered states. During the design stages, many users have added additional surface elements to decrease the set-up of fixturing time and expenses encountered in traditional subtractive production operations. Improper build plate adhesion and thermally induced warpage during FFF manufacturing can produce curved or otherwise distorted surfaces at the part-bed interface. Typically, part bottoms warp upwards away from the build plate. This warpage produces an overhang that can result in cracking and breakage during debinding and sintering; to ensure a flat bottom surface, adding extra material to the bottom of parts that can then be easily removed with typical cutting methods has been proven to provide increased flatness and thus improve crack reduction, stability in taller parts and other part outcomes.

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MIM 50%

FFF - XY 43%

FFF - Z 19%

Fig. 5 Elongation of MIM and Ultrafuse 316LX test specimens after debinding and sintering

Design for debinding & sintering Once the primary binders have been catalytically removed, only a small fraction of secondary binder remains and is used to provide structural integrity until sintering can consolidate the metallic contents. Part collapse is most likely during pre-sintering, in which final binder removal occurs in advance of full consolidation via sintering. This lowest point of structural stability dictates that overhang angles below 45°, which are easily achievable in FFF AM, may suffer collapse during sintering if not properly supported. Therefore, additional support structures, not typically required in AM, become necessary for the reduction of part distortion or to avoid collapse. Once adequate support has been provided, typical standard MIM process parameters apply.

Conclusion Thanks to very low capital investment requirements and the inherent ease of use of the FFF process, Ultrafuse 316LX offers manufacturers in various industries a cost-effective entry point into metal AM, thus allowing greater flexibility

during the design and testing phases when multiple iterations are being considered for a final part design. Ultrafuse 316LX enables the manufacture of low part number contracts, sample parts and preproduction prototypes with lead times not previously possible. The production of short-run replacements for legacy items is an exemplary application; this can be especially true when an existing mould is no longer available. Even greater benefits are available to those manufacturers already familiar with catalytic debinding and sintering operations within the MIM industry. Currently, BASF’s focus lies on offering 316L / 1.4404 stainless steel feedstock, however the broad range of Catamold feedstock will allow further portfolio expansions.

Contact BASF 3D Printing Solutions GmbH Email: printing@basf-3dps.com

References [1] Technical Information: Catamold®, B. A. (2003) on www.catamold.de: https://goo.gl/qx8CU9

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Sintering and properties of tool steels

A review of the sintering behaviour of selected tool steels processed by MIM MIM is a natural choice of fabrication method for complex parts in materials that are difficult to machine. Tool steels are one such class of material with significant potential applications growth, both for the MIM industry and for MIM-like Additive Manufacturing processes. In this study, Martin Kearns and colleagues from Sandvik Osprey review the sintering behaviour of popular tool steels such as D2 and M2, and present fresh data on a range of other tool steels, some made via both prealloy and master alloy routes. Materials investigated include AISI8620 and tool steels H11, H13, S7 and high carbon, high speed steel, T15, all sintered in nitrogen.

Powder metallurgical processes are well-suited to the production of hard materials in complex shapes where machining would be unfeasible or extremely costly. Ceramics and cermets are typically fabricated by press and sinter, powder extrusion or Ceramic Injection Moulding routes. In some metal systems too, tungsten alloys, stellites and tool steels are processed by the powder route, be it press and sinter or Metal Injection Moulding, for specific industrial applications where high hardness and wear resistance is required [1-3]. Examples include hand and power tool components, pump impellers and textile machinery applications. Tool steels typically have carbon content in the range 0.4-1.5% and heat treatment cycles are carefully controlled to achieve the optimum distribution of matrix carbides to deliver required wear performance. Conventionally, there are six main groups of carbon-containing tool steels: water-hardening, cold-work, shock-resisting, high-speed, hotwork and special purpose types. MIM parts makers have a full range of powder options from these families

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including popular alloys such as H13, S7, A2, M2, D2 and T15 which offer increasing hardness with increasing carbon content. The choice of alloy for a specific application will depend on cost, working temperature, required surface hardness, strength, shock resistance and toughness requirements. For more severe service environments, higher levels of refractory carbide formers (e.g. W, Mo) are used to maintain hot hardness and abrasion resistance. M2 is an example of a

high-speed tool steel which is widely adopted in MIM despite challenges posed by its narrow sintering window. This is probably the most widely used tool steel in MIM applications and it has been the subject of several studies [4-8]. The sintering mechanism in this and other high C tool steels is Super-Solidus Liquid Phase Sintering (SSLPS) and densification occurs rapidly once a liquid phase is formed at grain boundaries. Grain growth also tends to occur rapidly and, as the liquid film thickness

UTS, MPa

El %

Density g/cc

Hardness HT (HRC)

8620 AFT Data [15]

190

4

7.5

55

8620 Catamold [16]

200 (AS), 650(HT)

3

7.4

210 HRB (600-750 HRB*)

H13 [17]

1000

-

7.0 (1350°C)

41

S7 [18]

1750

2

7.3

45-53

T15 [6]

-

-

8.2

53 (AS)

Material

*case hardened

Table 1 Mechanical property data for different steels in sintered (AS) and heat treated (HT) condition

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Sintering and properties of tool steels

increases, the likelihood of distortion also increases. There have been fewer studies concerning other tool steels in relation to MIM, though reports on sintering of low alloy steels (AISI4140, 4340 and 4605) having similar carbon levels to H11, H13 show sintered density (nitrogen atmosphere) to improve as temperature rises towards the liquidus [9,10]. Lin [11] has described sintering of SKD-11, a close analogue of D2, demonstrating that gas atomised powders give widest processing windows, particularly when a finer size distribution is used (90% - 16 µm vs 90%-22 µm). Aside from these common tool steels, other materials have been adopted for tooling applications including case hardening steels and maraging steels. For parts makers who wish to preserve a tough core and develop surface hardness, AISI8620 steel is among those low carbon alloys that can achieve 60 HRC after post-sinter carburising treatment. Maraging steel 18Ni300 has been widely adopted in Additive Manufacturing because it is readily fabricated

by Powder Bed Fusion processes and can develop high hardness (55 HRC) after heat treatment [12]. It has been shown that high strength and hardness levels can also be achieved via MIM [13]. There is relatively little information published on the MIM processing of tool steels and one purpose of this study is to assess the sintering of less well characterised tool steels and their response to heat treatment. In addition to AISI8620, it examines the behaviour of H11, H13, S7 and T15 tool steels which are used in diverse applications. In the case of 8620 and H13, we contrast processing behaviour when parts are made from prealloyed or master alloy plus carbonyl iron powders (CIP). Numerous previous studies have shown the advantages that can be obtained via a master alloy approach including higher density and lower distortion [1, 9,10]. These are important considerations when coining and finishing operations will inevitably be more difficult and costly for hard materials which are intrinsically

more brittle and difficult to fabricate. Recognising the criticality of carbon control on sintering behaviour and finished part properties, a focus of the current study has been to evaluate carbon loss during sintering and heat treatment to relate this to the chemistry of starting powders. Table 1 shows a range of published values for properties of several tool steels. H11 and H13 are tough, high-strength tool steels suited to hot work environments such as for extrusion and forging dies. MIM tooling is often made from hardened steel, such as S7 or H13 [14]. S7 is widely used in plastic injection, compression and transfer moulds and componentry including core and ejector pins. High hardness and good impact toughness means it can also be used for coining tools and punches. T15 is a highly alloyed tool steel used in high-performance broaches, milling cutters, end mills, taps and reamers etc. The high V level increases wear resistance and W, Co improve high temperature performance [1-3].

Alloy

Fe

Cr

W

Mo

V

Co

Ni

Mn

Si

N

C

O

S

P

8620 PA

Bal

0.60

-

0.22

-

-

0.60

0.70

0.27

0.02

0.25

0.11

0.005

0.01

8620 MA

Bal

1.77

-

0.61

-

-

1.77

2.25

0.85

0.03

0.64

0.10

0.007

0.01

H11

Bal

5.35

-

1.28

0.45

-

-

0.46

1.09

0.05

0.37

0.12

0.008

0.01

H13

Bal

5.09

-

1.59

1.08

-

-

0.32

0.90

0.06

0.43

0.11

0.009

-

S7

Bal

3.30

-

1.50

0.27

-

-

0.30

0.32

0.03

0.56

0.14

0.01

-

T15

Bal

4.63

12.6

0.50

4.88

4.91

0.05

0.38

0.34

0.07

1.63

0.11

0.024

0.03

CIP BC

Bal

-

-

-

-

-

-

-

-

0.01

0.035

0.20

0.001

-

Table 2 Chemical analysis of powders used in this study

Material

Nominal psd

D10

D50

D90

Melt flow rate g/10 min

App Dens g/cc

Tap Dens g/cc

Hausner Ratio

Moisture %

S7 PA

90% - 22 µm

4.37

10.65

21.59

350

3.57

4.62

1.29

0.05

H11 PA

90% - 22 µm

4.05

10.16

20.97

360

3.62

4.54

1.25

0.06

H13 PA

90% - 22 µm

4.06

9.95

21.17

475

3.57

4.54

1.27

0.06

T15 PA

90% - 22 µm

5.47

11.95

21.93

455

3.84

4.80

1.25

0.05

8620 PA

90% - 16 µm

3.72

8.39

15.65

320

3.33

4.38

1.32

0.06

8620 MA

90% - 22 µm

4.50

12.94

21.81

3.62

4.80

CIP BC

90% - 12 µm

2.60

5.60

11.20

3.04

4.46

215

1.425

0.05 0.04

Table 3 Particle size and Tap Density data for powders used in this study

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While this article focuses on MIM processes, it is worth noting that results are also relevant to practitioners of binder jet Additive Manufacturing who face a common challenge in optimising the sintering of green parts.

Experimental procedure

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Fig. 1 Melt flow rate of MIM feedstocks vs Hausner Ratio of starting powders

W(V)=1E-2, W(N)=0; 1600

1:*M6C 2:*M23C6 3:*BBC_A2

1400

4:*FCC_A1#2

LIQUID+FCC_A1

5:*FCC_A1#1

BCC_A2+FCC_A1 FCC_A1

6:*LIQUID 7:*M7C3

1200 TEMPERATURE_CELSIUS

A series of prealloy (PA) and master alloy (MA) powders was produced by Sandvik Osprey’s proprietary inert gas atomisation process using nitrogen gas. The ‘as-atomised’ powders were air classified to 90%-22 µm or 90%-16 µm size ranges. The chemistry and particle size distribution data of each powder batch used in the study are shown in Tables 2 and 3 respectively. In the case of 8620 MA, an addition was made of low C CIP made by Sintez. The MA was formulated with a 3x concentration of main alloying elements with 0.7%C to which could be added low-carbon CIP powder. The carbonyl iron powder is significantly finer than the gas atomised powders and, when added to the MA, reduces the median size distribution to more closely replicate a typical 90%-14 µm powder size distribution. Feedstocks were prepared by TCK using its proprietary binder formulation to achieve a powder loading level of 61.8% corresponding to a 17.4% shrinkage factor. This shrinkage factor is typical of the target value in previous studies with gas atomised powders [9,10]. This is the sizing factor applied to the final part dimensions to design the mould. The feedstocks were moulded in an Arburg injection moulding unit to produce green standard MIMA tensile and Charpy test specimens [19]. Fig. 1 shows a correlation between the Hausner Ratio (Tap Density / Apparent Density) vs Melt Flow Rate, which shows the expected correlation between better packing of particles (low Hausner Ratio) and easier flow (higher melt flow rates). Moulded green parts were subject to an initial solvent debind (LÖMI GmbH) followed by thermal

8:*CEMENTITE 9:*GRAPHITE

FCC_A1+FCC_A1#2

1000

10:*M3C2 11:*MU_PHASE 12:*SIGMA#2

800 600 400 200 0

0.1 0.2

0.3 0.4

0.5

0.6

0.7

0.8 0.9

1.0

MASS_PERCENT C

Fig. 2 Phase stability in H13 Tool Steel: Thermocalc simulation with 0.43%C indicated as red dashed line

Material

Melt onset °C

Melt peak °C

Solidification onset °C

8620 PA

1470 - 1480

1480 - 1490

1472 - 1480

8620 MA

1350 - 1385

1460 - 1469

1440 - 1460

S7 PA

1372 - 1411

1475 - 1485

1470 - 1480

H11 PA

1410 - 1420

1460 - 1475

1470 - 1480

H13 PA

1375 - 1390

1477 - 1483

1468 - 1472

T15 PA

1466 - 1470

1493 - 1497

1487 - 1490

Table 4 Range of melting and solidification ranges determined from DSC analyses (10°C/min in Ar)

debind and sintering in a nitrogen atmosphere in an Elnik Systems furnace. The temperature profile adopted was to ramp to 750°C at

2°C/min (hold 1 h), ramp at 3°C to 1150°C (hold 1.5 h) and finally ramp at 5°C/min to sinter temperature (hold 3.5 h) followed by furnace cool.

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DSC/(μV/mg) 0.30

exo

Onset*: 1217.7°C

Value: 384.0°C, 0.14815 μV/mg

0.25 0.20

Value: 1472.1°C, 0.047253 μV/mg

Value: 1274.7°C, 0.073114 μV/mg Onset*: 1439.4°C

101.0 100.8 100.6

0.15

100.4

0.10

100.2

0.05

100.0

0.00

Onset*: 1389.6°C

-0.05

99.8

Value: 745.0°C, 0.012258 μV/mg

Onset*: 1409.4°C Onset*: 1483.8°C Value: 904.0°C, 0.03511 μV/mg

-0.10 -0.15

TG/%

200

400

600 800 1000 Temperature/°C

1200

99.6 99.4

1400

Fig. 3 Phase stability in H13 Tool Steel: DSC trace showing endotherms (red) and exotherms (blue)

Sinter T °C

Hold T °C

Quench

Temper °C

Cooling

8620 PA

1360

800

Warm oil

180

Air cool

8620 MA + CIP

1360

800

Warm oil

230

Air cool

H11

1360

1030

Warm oil

550

Air cool

H11 MA + CIP

1400

940

Warm oil

230

Air cool

H13

1360

940

Warm oil

230

Air cool

S7

1360

940

Warm oil

230

Air cool

T15

1240

1200

Warm oil

550

Air cool

M2*

1250

1200

Warm oil

550

Air cool

Alloy

Table 5 Heat treatment conditions for tool steel samples (air atmosphere)

Material

Lot Number

Nominal psd

Avg Density, g/cc

S7 PA

17D1616

90% - 22 µm

91.83

H11 PA

17D1617

90% - 22 µm

91.30

H13 PA

17D1658

90% - 22 µm

90.85

T15 PA*

17D1620

90% - 22 µm

99.60

8620 PA

17D1619

90% - 16 µm

93.15

8620 MA + CIP

17D1618

90% - 14 µm

95.25

Table 6 Density of MIM specimens achieved after sintering in nitrogen at 1360°C (*T15 at 1240°C)

Sintering was carried out at 1360°C for all alloys other than T15 which was sintered at 1240°C. The choice of sintering temperature was guided by DSC studies on powder samples which provided insights into the onset of melting on heating at 10°C/min and cooling @ 10°C/min under Ar (Fig. 2).

92

Table 4 shows the range of temperatures from three separate DSC runs. These data were compared with Thermocalc studies on corresponding alloys to relate endotherms to phase transitions on heating and crystallisation events on cooling (see red and blue traces respectively in Fig. 3).

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Sintered density measurements were carried out using a Micromeritics Accupyc model 1340 Helium Pycnometer. The carbon level of the final sintered specimens was measured using Eltra combustion analysis. For each sintering run, Charpy bars were mounted on refractory supports both cantilever style (15 mm overhang) and suspended across refractory supports (38 mm separation) to determine the extent of distortion as a function of alloy type and sintering temperature. As-sintered tensile samples were tested in triplicate in accordance with ASTM E8-08. Vickers hardness testing was carried out on tensile bar tabs using a 10 kg weight and results converted to HRC using standard tables. Polished sections of tensile specimen tabs were prepared for microstructural analysis by etching in Nital. The heat treatments applied to different specimens are shown in Table 5. Heat treatment was carried out in air without any special provisions to avoid decarburisation.

Results Table 6 shows the density values obtained for different alloys after sintering in nitrogen at 1360°C or 1240°C in the case of T15. Except for T15, which achieved nearly full density (99.6% theoretical), the lower carbon tool steels showed modest final density levels in the range 91-93%. The 8620 prealloy achieved just over 93% density while the same composition produced via a master alloy reached over 95% theoretical density. Fig. 4 shows metallographic sections of as-sintered tool steel specimens. 8620 alloy shows a mixed ferrite and fine pearlite structure with the master alloy variant exhibiting a lower level of porosity and a coarser grain size. Pores are fine and evenly dispersed. H11 exhibits a higher level of porosity than 8620 and is darker etching reflecting higher carbon and a martensitic structure. The master alloy variant which was sintered at a higher temperature shows an uneven distribution of porosity and

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with the more needle-like martensitic structure of H13. T15 shows aashows uniform microstructure of mixed mixed with the more needle-like martensitic structure H13. T15 shows aa uniform microstructure mixed with the more needle-like martensitic structure of H13. T15 shows aa uniform microstructure of mixed with the more needle-like martensitic structure of H13. T15 microstructure of mixed with the more needle-like martensitic structure of H13. T15 shows uniform microstructure of with the more needle-like martensitic structure of of H13. T15 shows uniform microstructure of of mixed with the more needle-like martensitic structure of H13. T15 shows aa uniform uniform microstructure of mixed with the more needle-like with the with more the needle-like more needle-like martensitic martensitic structure structure of H13. of T15 H13. shows T15 a shows uniform uniform microstructure microstructure of mixed of mixed with the more needle-like martensitic structure of H13. T15 shows a uniform microstructure of mixed carbides. carbides. with the with more the needle-like more needle-like martensitic martensitic structure structure of H13. of T15 H13. shows T15 a shows uniform a uniform microstructure microstructure of mixed of mixed carbides. withcarbides. with the with the more the more needle-like more needle-like needle-like martensitic martensitic martensitic structure structure structure of H13. of H13. of T15 H13. T15 shows T15 shows a shows uniform a uniform a uniform microstructure microstructure microstructure of mixed of mixed of mixed carbides. carbides. carbides. carbides. carbides. carbides. carbides. carbides. carbides. carbides. carbides. carbides. Alloy Polished (100x) Etched (100x) Etched (200x) Alloy Polished (100x) Etched (100x) Etched (200x) Alloy Polished (100x) Etched (100x) Etched (200x) Polished Etched Etched Alloy Polished (100x) Etched (100x) Etched (200x) Alloy Polished (100x) Etched (100x) Etched (200x) Alloy Alloy Polished (100x) Etched (100x) Etched (200x) Alloy Polished (100x) Etched (100x) Etched (200x) Alloy Polished (100x) Etched (100x) Etched (200x) Alloy Alloy Polished Polished (100x) (100x) Etched Etched (100x) (100x) Etched Etched (200x) (200x) (100x) (100x) (200x) Alloy Polished Alloy Alloy Polished (100x) (100x) Etched Etched (100x) (100x) Etched Etched (200x) (200x) Alloy Alloy Alloy Polished Polished Polished Polished (100x) (100x) (100x) Etched Etched Etched (100x) (100x) (100x) Etched Etched Etched (200x) (200x) (200x) 8620 8620 8620 8620 8620 8620 86208620 8620 8620 8620 8620 8620 8620 86208620 8620

8620 8620 8620 8620 8620 8620 8620 8620 8620 8620 8620 8620 8620 MA ++ MA + MA + 8620 8620 8620 MA 8620 MA + MA + MA MA ++ + MA + MA + MA + MA MA + MA CIP CIP CIP MA MA + MA + + + CIP CIP CIP CIP CIP CIP CIP CIP CIP CIPCIP CIPCIP CIP

H11 H11 H11 H11 H11 H11 H11 H11 H11 H11H11 H11 H11 H11H11H11 H11

H11 H11 H11 H11 H11 H11 H11 H11 H11 H11 H11 H11 H11 H11 MA + MA H11 H11 H11 MA MA + MA + MA + ++ MA + MA + MA + MA + MA + MA + MA + MA + CIP CIP CIP MA MA + MA + + CIP CIP CIP CIP CIP CIP CIP CIP CIP CIP CIP CIPCIPCIP

H13 H13 H13 H13 H13 H13 H13 H13 H13 H13 H13 H13 H13 H13H13H13 H13

S7 S7 S7 S7 S7 S7 S7 S7 S7 S7 S7 S7 S7 S7 S7 S7 S7

T15 T15 T15 T15 T15 T15 T15 T15 T15 T15 T15 T15 T15T15 T15T15 T15

Fig. 4 Metallography of different tool steels. Polished and etched sections. All sintered at 1360°C with exception ooo of oH11ooo Fig. Metallography of different tool steels. Polished & etched sections. All sintered Fig. 3 Metallography of different tool steels. Polished & etched sections. All sintered at 1360 with Fig. 3333Metallography of different tool steels. Polished & etched sections. All sintered at oC with oC oC with 3MA Metallography of different tool steels. C1360 with Fig. 33 Metallography of different tool steels. Polished & etched sections. All sintered at 1360 Fig. Fig. Metallography of different tool steels. Polished & etched sections. All sintered ooC ooC with Fig. Metallography of different tool steels. Polished & etched sections. All sintered at 1360 with Fig. 3 Metallography Fig. Metallography of different of different tool steels. tool Polished steels. Polished & etched & sections. etched sections. All sintered All sintered at 1360 at 1360 with (1400°C) and T15 (1240°C) oooC o o o o Fig. 3 Fig. 33 Metallography of of different tool steels. tool Polished steels. Polished & etched & sections. etched sections. All sintered All sintered at 1360 at C 1360 with C Fig. Metallography of different tool steels. Polished & etched sections. All sintered at 1360 C with o o o o o o o o Fig.Fig. Fig. 3 Metallography Metallography Fig. Metallography Metallography of different different of different of different tool tool steels. tool steels. Polished steels. Polished & etched & sections. etched sections. All sintered All All sintered sintered at 1360 at 1360 at C 1360 with C with C with with 333Metallography of different tool steels. Polished & etched sections. 1360 C with exception of H11 MA (1400 C) and T15 (1240 C) exception of H11 exception of H11 MA (1400 and T15 (1240 oC) oC) oC) oC) oC) oC) exception of H11 MA (1400 and T15 (1240 exception of H11 MA (1400 and T15 (1240 C) exception of H11 MA (1400 C) and T15 (1240 C) ooC) ooand ooC) ooC) exception of H11 MA (1400 C) T15 (1240 exception exception of H11 of MA H11 (1400 MA (1400 T15 C) and (1240 T15 (1240 ooC) ooand exception exception of H11 of MA H11 (1400 MA C) (1400 and T15 C) and (1240 T15 C) (1240 C) exception of H11 MA (1400 C) and T15 (1240 C) exception exception exception of H11 of H11 H11 of MA H11 (1400 MA C) (1400 and T15 C) and (1240 T15 (1240 C) (1240 C) C) exception of MA (1400 C) and T15

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Alloy

Start %C

Start %O

Sinter %C

ΔC start vs sintered

%C after HT

ΔC sintered vs HT

Start %N

%N after HT

Molar ratio C/O2

8620 PA

0.25

0.11

0.20

0.05

0.19

0.01

0.02

0.02

1.2

8620 MA + CIP

0.28

0.17

0.21

0.07

0.21

0.00

0.03

0.02

1.1

S7 PA

0.56

0.14

0.50

0.06

0.41

0.09

0.03

0.04

1.1

H11 PA

0.37

0.12

0.32

0.05

0.24

0.08

0.05

0.06

1.1

H13 PA

0.43

0.11

0.39

0.04

0.33

0.06

0.06

0.07

1.0

T15 PA

1.65

0.11

1.52

0.13

0.71

0.79

0.07

0.97

3.2

Table 7 Progression in %C, N, O levels in tool steels from starting powder to sintered product and ultimately heat treated products

3.50 Sag or drape (mm)

a much coarser grain size and microstructure. The H13 micrographs bear a close similarity to H11 as may be expected based on chemistry and sintered density. S7’s microstructure also resembles H13 but the phase structure shows coarser bainite laths compared with the more needle-like martensitic structure of H13. T15 shows a uniform microstructure of mixed carbides. Table 7 shows that, during the sintering process, carbon is lost from each of the alloys and the amount lost is, in all but one instance, predictable based on the amount of oxygen in the starting feedstock. The column showing the calculated molar ratio C/O2 is close to unity in most cases, suggesting that carbon has been lost as CO2 and that, once the available oxygen has been consumed, carbon level remains stable. Exceptional behaviour is shown by T15 whose C loss is far higher than

3.00 2.50 2.00 1.50 1.00 0.50 0.00

S7

H11

H13

Cantilever (15mm)

T15

8620 PA

8620 MA

Drape (38mm)

Fig. 5 Deflection of Charpy bars mounted in cantilever or suspended form during sintering at 1360°C

would have been expected based on the oxygen level in the feedstock. There are a few possible explanations for this: a high starting C level would encourage C to be lost as CO rather than CO2 but more likely is that some C has been displaced by

nitrogen during sintering in nitrogen. Certainly, the nitrogen level in the heat-treated specimen has risen dramatically at the expense of carbon and, while we do not have a direct measurement of nitrogen in the sintered sample, it is reasonable

Material

Nominal psd

Density, %TD

0.2%PS, MPa

UTS, MPa

%El

VHN

HRC

8620 PA

90% - 16 µm

93.15

280

507

15.0

138**

-

8620 MA + CIP

90% - 14 µm

95.25

339

585

13.8

164**

-

H11

90% - 22 µm

91.30

967

1760

4.7

437

44

H11 MA + CIP

90% - 14 µm

93.30

1070

1245

0.7

572

54

H13

90% - 22 µm

90.85

902

1600

4.3

402

42

S7

90% - 22 µm

91.83

763

1330

9.2

336

36

T15

90% - 22 µm

99.60

1097

1280

0.8

550

52

M2*

80% - 22 μm

99.9

1230

1471

1.5

579

54

*From ref. 7; ** normally increased by case hardening (carburising)

Table 8 Mechanical properties of as-sintered specimens

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Sintering and properties of tool steels

Material

Nominal psd

Density g/cc

0.2% PS MPa

UTS MPa

%El

VHN

HRC

8620

90% - 16 µm

93.15

680

990

5.0

257

26

8620 MA + CIP

90% - 14 µm

95.25

760

1080

5.0

270

28

H11

90% - 22 µm

91.30

1110

1450

4.6

407*

42

H11 MA + CIP

90% - 22 µm

93.30

1190

1440

2.2

404*

42*

H13

90% - 22 µm

90.85

957

1245

3.7

374*

39

S7

90% - 22 µm

91.83

1235

1590

4.5

424**

44**

T15

90% - 22 µm

99.60

-

830

0.5

816

65

M2* [7]

80% - 22 μm

99.9

1200

1330

-

890

66

Table 9 Mechanical Properties of Heat treated specimens. * data from decarburised surfaces; ** data from cross-section of decarburised sample vs surface value of 29 HRC to speculate that part of the 0.13% drop in %C on sintering of T15 is down to substitution by nitrogen. In any event, the carbon losses across all tool steels are quite modest, predictable and can be compensated for as required. Table 8 shows the results of tensile and hardness testing of the different tool steel variants and results from a previous study on M2 are included for comparison (7). In the case of 8620 low alloy steel, the master alloy provides a significantly higher strength and hardness level than the prealloy, without compromising ductility. For H11 however, the ductility of the master alloy is much lower than that of the prealloy and so, while yield strength and hardness are superior, the ultimate tensile strength is lower. The hardness shown by H11 MA (54 HRC) is the highest as-sintered value obtained from all steels in the present study. H13 tool steel properties are similar to H11 with slightly lower strength and hardness despite having a higher carbon level. The S7 product has lower hardness again than the H13 steel but significantly higher ductility, suggesting that full hardenability has not been realised in the sintering process. T15 exhibits the highest yield strength of the steels and its property set is close to that of H11 but with a slightly lower hardness of 52 HRC. On removal from the sintering furnace, it was apparent that several of the suspension and cantilever samples had failed: both T15 test specimens and the H13 cantilever

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specimen. From the surviving specimens, drape values were measured as the deflection of the cantilever and the maximum sag of the suspended test bars. Fig. 5 summarises the results and it is apparent that 8620, the lowest strength and most ductile material, exhibits greatest deflections in the prealloy form, but the deflections are much lower in 8620 made by a master alloy route. Indeed, despite its more modest strength and higher ductility, it shows less distortion than any of the other tool steels.

while T15 displays highest hardness (65 HRC), but low ductility and tensile strength. H11 and H13 on the other hand show moderately increased strength levels but lower hardness. Fig. 6 shows microstructures of selected heattreated samples to contrast with as-sintered structures in Fig. 4. 8620 shows a tempered martensitic structure without evidence of significant grain growth. H11 does not display the needle like martensite evident in the as-sintered microstructure and

“For H11 however, the ductility of the master alloy is much lower than that of the prealloy and so, while yield strength and hardness are superior, the ultimate tensile strength is lower...” Tool steels are usually heat treated to develop maximum hardness and heat treatments were devised for each of the tool steel variants based on literature sources. The conditions used are summarised in Table 5. The data in Table 9 show that 8620, S7 and T15 have undergone some degree of hardening. 8620 and S7 exhibit significantly higher strength and hardness while retaining decent ductility levels,

exhibits coarse grain structure which, together with lower C (see Table 7) begins to explain its fall in hardness. The PA and MA versions of H11 show heat treated hardness levels of 42 HRC, representing a significant degree of softening for the MA variant in particular. The final carbon level in H11 PA of 0.24% is much lower than the typical level of 0.38% for this grade. H13 shows similarities to the H11 PA but here there is also evidence of grain

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Sintering and properties of tool steels

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aa tempered martensitic structure without evidence of significant grain growth. H11 does not martensitic structure without evidence of significant grain growth. H11 does not aa tempered tempered martensitic structure without evidence of significant grain growth. H11 does not tempered martensitic structure without evidence of significant grain growth. H11 does not edle like martensite evident in the as sintered microstructure and exhibits coarse grain structure tempered martensitic structure without evidence of significant significant grain growth. growth. H11 does not grain structure like martensite evident in the as sintered microstructure and exhibits coarse a0aedle tempered martensitic structure without evidence of grain H11 does not not grain structure like evident in the as sintered microstructure and exhibits coarse grain structure shows amartensite tempered martensitic martensitic structure without evidence of significant grain growth. H11 does structure without evidence of significant grain growth. H11 does not 00edle shows a tempered without evidence of significant grain growth. H11 does not edle like martensite evident in the as sintered microstructure and exhibits coarse grain structure shows a tempered martensitic without evidence of significant grain growth. H11 does not structure without evidence of significant grain growth. H11 does not shows edle like martensite evident evident in the asinsintered microstructure and exhibits coarse graingrain structure lay the needle like martensite the as sintered microstructure and exhibits coarse structure boundary carbide films which indilay evident in the as sintered microstructure and exhibits coarse grain structure ay the needle like martensite sintered microstructure and exhibits coarse grain structure Alloy Heat treated (200x) As sintered (200x) lay the needle like martensite evident in the as sintered microstructure and exhibits coarse grain structure ay the needle ay like martensite and exhibits coarse grain structure Heat treated sintered microstructure As-sintered Alloy treated (200x) As sintered (200x) AlloyHeat Alloy Heat treated (200x) As sintered (200x) cate the matrix has been denuded Alloy Heat treated (200x) As sintered (200x) (200x) (200x) Alloy Heat treated (200x) As (200x) Alloy Alloy (200x) (200x) As sintered sintered (200x) Alloy Heat treated Heat treated treated As sintered (200x) Heat As (200x) (200x) As sintered sintered (200x) in carbon leading to a reduction in Heat treated (200x) (200x) As sintered (200x) Alloy (200x) As sintered (200x) hardness to 39HRC. S7 likewise 8620 8620 8620 8620 8620 8620

shows a coarse microstructure bainitic microstructure. T15 appears, in contrast to others, to have a more refined and uniform microstructure and Table 7 shows that its chemistry has changed markedly with carbon having been displaced significantly by nitrogen.

8620 8620 8620 8620 8620

8620 8620 8620 8620 MA 8620 8620 8620 MA + 8620 8620+ 8620 MA + 8620 MA + MA ++ CIP MA MA + MA + CIP MA MA + CIP MA ++ CIP CIP CIP CIP CIP CIP CIP

Discussion

The purpose of this study was to examine the sintering behaviour of some popular tool steel grades of interest to the MIM and Additive Manufacturing communities. The choice of 1360°C as a sintering H11 H11 H11 H11 temperature for most of the alloys H11 H11 H11 H11 H11 H11 H11 was guided by Thermocalc and DSC studies and has not been optimised for any single alloy. Likewise, the use of nitrogen as the sintering atmosphere was a pragmatic first step and deeper analysis, beyond the H11 H11 H11 H11 H11 scope of this study, may reveal other H11 H11 MA + H11 MA + H11 MA + MA ++ H11 atmospheres to be advantageous in MA + MA MA + MA + MA + CIP CIPCIP MA + CIP CIP achieving higher sintered density. MA + CIP CIP CIP CIP CIP Indeed Liu et al. [5] and Varez et al. CIP [6] have determined that, in vacuum, densification of M2 tool steel occurs at much lower temperatures than in nitrogen and an increase of 60°C is needed in order to achieve H13 H13 H13 H13 H13 H13 similar densification in a nitrogen H13 H13 H13 H13 H13 atmosphere. This is attributed to H13 the stabilising effect of nitrogen on austenite and the elevation of the liquidus temperature with increasing nitrogen. T15 however achieved high S7 S7 density after sintering at 1240°C in S7 S7 S7S7 S7 S7 S7 nitrogen and, with optimised heat S7 S7 S7 treatment, hardness values well above 65 HRC should be possible. The dramatic change in chemistry on heat treatment of T15 with C falling from 1.52% to 0.79% while N T15 rose from 0.07 to 0.97% must have T15 T15 T15 T15 T15 a significant effect on properties, T15 T15 T15 T15 T15 the use of vacuum heat treatment T15 T15 in future should maintain the starting carbon level. The net effect Fig. 5 Metallography of different tool steels. Polished & etched sections. Fig. 55 Metallography Metallography of different tool steels. Polished & etched sections. Fig. of different tool steels. Polished & etched sections. Fig. 55 Metallography Metallography of different different tool steels. steels. Polished & etched etched sections.of nitridation and decarburisation Fig. of tool Polished & sections. Fig. 55 Metallography of different tool steels. Polished & etched sections. Fig. Metallography of different tool steels. Polished & etched sections. Fig. 6 Metallography of different tool steels polished and etched sections on hardness is difficult to estimate Fig. 5 Metallography of different tool steels. Polished & etched sections.

Fig. 5 Metallography of different tool steels. Polished & etched sections. Fig. Fig. 55 Metallography Metallography of of different different tool tool steels. steels. Polished Polished & & etched etched sections. sections. 96

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70 60 HRC

and there are few references to the hardness of carbide and nitride phases [20]. For the remaining alloys in this study, density levels of 91-95% are relatively modest by MIM standards but are at a level where post-HIP treatment may enhance mechanical properties if desired. For 8620, the density and strength level values reported before and after heat treatment are in line with values reported by parts makers [15,16] and, in practice, parts would likely be subjected to further treatments such as case hardening to enhance surface hardness. The MA approach, using a 3x concentrate 8620 alloy and compounding with 2 parts CIP has again been confirmed to be advantageous in achieving higher density, enhanced mechanical properties and lower distortion than evident in PA 8620. Table 4 shows that the MA itself shows earlier onset of melting (higher C) and fine CIP will also accelerate the sintering process. Fig. 7 shows a summary of hardness values expected of popular tool steels with the open range indicating the typical working hardness ranges. Superimposed on this, black symbols indicate the peak hardness values determined in this study. For comparative purposes, hardness ranges for 3 other common tool steels (D2, M2, 18Ni300) are shown along with green symbols highlighting data obtained from three other MIM studies featuring Sandvik Osprey’s gas atomised powders [7,11,13]. In this study, H11 and T15 met hardness expectations, but H13 and particularly S7 did not. Reasons for this may be found in a lack of densification on sintering, inhibited to some extent by the nitrogen sintering atmosphere (6) and by some degree of carbon loss on sintering, but more so on heat treatment. Indeed, the carbon loss on sintering itself is shown, in Table 7, to be quite modest and predictable based on the starting level of oxygen in the powder components. The greater loss of carbon on heat treatment is a concern, not only because it

Sintering and properties of tool steels

Vol. 12 No. 3 © 2018 Inovar Communications Ltd

50 40 30 H11

H13

S7

D2

M2

T15

18Ni300

Fig. 7 Typical min/max working hardness ranges for different tool steels (2). Black symbols- values achieved in this study; green symbols (D2/SKD-11 – Lin et al [11]; M2 & 18Ni300 – Kearns et al. [7,13])

is a variable, but because, unlike the sintering losses, it is a surface rather than a bulk phenomenon. As shown in the footnote of Table 9, the hardness of S7 for example is 15 HRC higher in the bulk compared with its decarburised surface. Values for H11 and H13 samples, also heat treated in air, and T15, must therefore be seen as sub-optimal and representative of decarburised surfaces. The hardness and tensile properties measured on heat treated samples should be treated with caution.

Summary and conclusions The present study shows that a range of popular tool steels can be sintered to > 91% density in nitrogen gas at 1360°C and, under these conditions, sintered properties are somewhat below expectations of conventional tool steels. Peak as-sintered strength is shown by H11 (PA) tool steel (1760 MPa) while peak hardness (54 HRC) is exhibited by H11 (MA). In the case of H11, H13 and

“The fact that carbon control is predictable following the sintering stage is an important finding, confirming previous studies and highlighting the benefits of using gas atomised metal powders with relatively low and consistent oxygen levels..” The fact that carbon control is predictable following the sintering stage is an important finding, confirming previous studies and highlighting the benefits of using gas atomised metal powders with relatively low and consistent oxygen levels. Variable carbon levels within what is a narrow sintering window for tool steels makes control of hardness and part tolerances challenging.

S7, low density is attributed to sintering being inhibited by the nitrogen atmosphere that tends to stabilise austenite and retard the overall hardening process. 8620 on the other hand achieves good property levels, at least in line with published values and the master alloy approach to making this alloy yields benefits in density, properties and dimensional stability: 8620

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Sintering and properties of tool steels

and H13 made via a master alloy route achieve ~2-3% higher density than their prealloy equivalents at 1360°C. T15 achieved excellent hardness levels in the as-sintered and heat treated conditions (65 HRC), albeit the heat treated material features a much reduced carbon level, offset by a gain in nitrogen from the heat treatment environment. Heat treatment of H11, H13 and S7 resulted in some additional decarburisation, which depressed hardness values. Carbon loss on sintering is modest and explained by combination with oxygen from powders to form CO2 in all cases but T15, where nitrogen substitution is suspected to play a part in carbon loss. Low oxygen level in gas atomised powder is advantageous in moderating carbon loss and controlling final part tolerances.

[2] www.crucible.com/eselector/ general/generalpart1.html

Acknowledgements

[8] G Herranz et al., Sintering process of M2 HSS feedstock reinforced with carbides, PIM International, Vol. 4 No.2 June 2010, 60-65

Grateful thanks are due to Dr Shahin Mehraban and Dr Nick Lavery of University of Swansea for DSC studies, and to Agneta Östberg, Anders Willson, Dr Peter Harlin and Linn Larsson of Sandvik Materials Technology for Thermocalc and metallographic analyses. Our appreciation also goes to Andrew Williams of Sandvik Osprey for specimen deflection measurements.

Author Dr Martin Kearns Powders Group Director Sandvik Osprey Limited Red Jacket Works Milland Road Neath SA11 1NJ United Kingdom Email: martin.kearns@sandvik.com www.materials.sandvik

98

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[3] G Hoyle, “High Speed Steels,” Butterworths & Co, London, 1988. [4] J V Bee et al., Sintering Mechanisms in Vacuum Sintered M2 and T15 High Speed Steel Powders, Metal Powder Report, 177-180, 182, March 1988 [5] Z Y Liu et al., Sintering of Injection Moulded M2 High Speed Steel, Materials Letters 45 (2000) 32-38 [6] A Varez et al., Sintering in Different Atmospheres of T15 and M2 HSS produced by modified MIM process, Mater. Sci. & Eng. A366 2004 318-324.

[17] R Beslera et al., Effect of Processing Route on the Microstructure and Mechanical Properties of Hot Work Tool Steel, Materials Research. 2017; 20(6): 1518-1524 [18] www.indo-mim.com/pdf/ mim_materials_leaflet.pdf [19] MPIF Standard 35 handbook. [20] A. Friedrich et al., Synthesis of Binary Transition Metal Nitrides, Carbides and Borides from Elements, Materials (Basel) 2011 Oct 4(10) 1648-1692.

[7] M A Kearns et al., Sintering and Properties of MIM M2 High Speed Steel Produced by Prealloy and Master Alloy Routes, Powdermet 2015

[9] A J Coleman et al., Effect of Particle Size Distribution on Processing and Properties of Metal Injection Moulded 4140 and 4340, Powdermet 2011, San Francisco, CA. [10] A J Coleman et al., Processing and Properties of MIM AISI 4605 via Master Alloy Routes, Powdermet 2012 [11] L Haotian, Metal Powder Injection Moulding of SKD-11 Die Steel: Powder and Process Characteristics, PMAROC 2009, Tai1wan [12] www.eos.info/material-m [13] M A Kearns et al., Studies on Metal Injection Moulding of Maraging Steel: Microstructure and Property Relationships, Powdermet 2016 [14] H Irrinki et al., Material Selection for the Production of Injection Moulding Tooling by Additive Manufacturing, Metal Additive Manufacturing, Summer 2016 2(2), 77-88

References

[15] www.aftmim.com/mim-designguide/material-properties.php

[1] A M Bayer et al., High Speed Tool Steels, ASM Handbook 16 Machining, 51-59 (1989)

[16] BASF Datasheet – Catamold® 8620, April 2006. www.basf.de/ catamold

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POWDERMET2019

International Conference on Powder Metallurgy & Particulate Materials 2 0 1 9

Additive Manufacturing with Powder Metallurgy

June 23–26, 2019

Sheraton Grand • Phoenix, Arizona

Call for Papers & Posters TECHNICAL PROGRAM Held with the co-located conference AMPM2019, Additive Manufacturing with Powder Metallurgy, POWDERMET2019 attendees will have access to over 200 technical presentations from worldwide experts on the latest research and development. TRADE EXHIBIT The largest annual North American exhibit to showcase leading suppliers of powder metallurgy, particulate materials, and metal additive manufacturing processing equipment, powders, and products. SPECIAL CONFERENCE EVENTS Including special guest speakers, awards luncheons, and evening networking events.

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PIM at POWDERMET2018

POWDERMET2018: The influence of material characteristics on the processing and properties of PIM parts A number of the papers presented during the technical sessions at the POWDERMET2018 conference, organised by the Metal Powder Industries Federation (MPIF) and held in San Antonio, Texas, June 17-20, 2018, addressed issues related to achievable properties and the influence of feedstock characteristics on the processing of Powder Injection Moulded products. This article presents a comprehensive review of selected conference papers in these categories.

The effects of grain size and pore size on the high cycle fatigue behaviour of injection moulded Ti-6Al-4V compacts The first paper on this subject was presented by Kentaro Kudo, Kazunari Shinagawa and Hideshi Miura of Kyushu University, Fukuoka, Japan, reporting a study of the effects of grain and pore size on the high cycle fatigue behaviour of metal injection moulded Ti-6Al-4V [1]. As a consequence of a number of previously reported studies, it is now possible to match the static properties (tensile strength, elongation) of wrought material with injection moulded Ti-6Al-4V. However, dynamic properties such as high cycle fatigue strength remain significantly below those of wrought material. There are two reasons for this: injection moulded Ti-6Al-4V compacts still contain some retained pores, and additionally have a coarse lamellar microstructure consisting of α and β

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phases as a result of sintering in the β single phase region. In the reported study, to improve the high cycle fatigue strength of injection moulded Ti-6Al-4V alloy compacts with pores, the authors focused on the influence of pore size and grain size. They controlled the grain size by changing the conditions

of sintering and heat treatment, and the pore size by adjusting powder particle size. In particular, the grain size was considerably refined by a hydrogenation and dehydrogenation (HDH) treatment, which had been newly developed for strengthening the Ti-6Al-4V alloy, and the effects of a wide

Fig. 1 The city of San Antonio, Texas, hosted the MPIF’s POWDERMET2018

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Microstructure refinement method

Typical MIM

HDH

α+β sintering5

Normal

Powder Sintering temperature Sintering time

Fine

1350 °C

980°C

1100, 1150, 1230, 1300°C

4h

24, 48, 96 h

2h

-

-

-

Heat treatment

Fine powder4

HDH

Table 1 Experimental conditions [1]

10

10

99.995

9

8

8

99.966

6

6

99.752

5

4

4

98.185

3

2

2

87.342

1

0

0

36.788

-1

-2

-2

0

10

20

30 40 50 Pore diameter [µm]

60

70

0.062

F [%]

y = -ln[ln{j/(n+1)}]

7

Typical MIM Typical MIM-HIP fine-1100℃ fine-1150℃ Fine-1230℃ Fine-1300℃ HDH HDH-HIP 980℃-24 h 980℃-24 h-HIP 980℃-48 h 980℃-96 h Fine-1100℃-HIP Fine-1300℃-HIP

Fig. 2 Results of extremal statistics [1]

range of grain size and pore size on the high cycle fatigue strength were investigated. Two types of powders with different particle size were used. The ‘normal’ particle size powder was manufactured by gas atomisation and had a median diameter of 28.8 µm, while the fine particle powder was manufactured by plasma atomisation and had a median diameter of 15.0 µm. The powder loading of the feedstock was set at 65 vol.% and the binder consisted of 69 mass% paraffin wax (PW), 10 mass% carnauba wax (CW), 10 mass% atactic polypropylene (APP), 10 mass% ethylene vinyl acetate polymer (EVA) and 1 mass% di-n-butyl phthalate (DBP). The feedstock, obtained by kneading the powders and binder, was injection moulded into tensile and fatigue test specimen dies. The green compacts were subjected

102

to solvent debinding in a heptane saturated atmosphere, followed by thermal debinding and sintering in a continuous vacuum furnace for various sintering temperatures and times. Hot Isostatic Pressing treated compacts were also prepared as comparative material, with the HIP conditions being set at 900°C for 2 h in a 103 MPa Ar atmosphere. The hydrogenation and dehydrogenation treatment (HDH) was performed on compacts made from normal particle size powder. Hydrogenation was conducted at 1000°C for 1 h for the solution treatment and 650°C for 4 h for the aging treatment in an atmosphere of H2 : Ar = 1:1 (vol.%). Dehydrogenation was conducted at 650°C for 12 h in vacuum, followed by cooling in the furnace. The experimental conditions are shown in Table 1. Compacts made from normal particle size powder were subjected to two types of sintering. One was β single phase

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region sintering, carried out at 1350°C for 4 h. The compacts sintered in the β region were also treated by HDH. The other sintering treatment was carried out in the α + β dual phase region to suppress grain growth during sintering and the conditions were set at 980°C, which is just below β transus temperature (1000°C) of Ti-6Al-4V, for 24, 48, and 96 h. The compacts made from fine particle powder were sintered at temperatures in the range 1100°C–1300°C for 2 h, i.e., at sintering temperatures lower than that of the compacts made from normal particle size powder. For wrought materials, it is well recognised that the largest inclusion has a great influence on fatigue strength and, therefore, this study sought to estimate the maximum pore size, by the method of Murakami using ‘extremal’ statistics. The results of extremal statistics are shown in Fig. 2. The lines descending perpendicularly to the x-axis from ymax of the approximate straight line for each data set represent the estimated value of the maximum pore diameter dmax. The compacts made from normal size powder showed dmax from 45–60 µm. The compacts made from fine size powder showed a smaller dmax from 20–35 µm. The compacts treated by HIP showed even smaller pore size, from 10–17 µm. In these compacts, maximum pore diameters were almost equal regardless of the difference in powder particle size. Table 2 shows various properties of sintered and HIP treated MIM Ti-6Al-4V alloy compacts. The relative densities of all compacts were above 95%, a level at which remaining pores would be closed. Although there were variations in the oxygen contents, the overall tendency observed was for an increase on using fine powder and applying a HIP treatment. However, all oxygen contents were below 0.35 mass% and previous published work had indicated that these levels would not exert an influence on elongation.

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PIM at POWDERMET2018

Relative density [%]

Oxygen content [mass%]

Grain diameter [µm]

Tensile strength [MPa]

Elongation [%]

Fatigue strength [MPa]

Typical MIM

97.4%

0.19%

149 µm

837 MPa

15.1%

291 MPa

Typical MIM-HIP

99.9%

0.32%

162 µm

1033 MPa

10.5%

331 MPa

HDH

97.5%

0.25%

3.5 µm

1018 MPa

6.0%

470 MPa

HDH-HIP

100%

0.31%

4.5 µm

1032 MPa

6.7%

635 MPa

980°C-24 h

96.3%

0.25%

19 µm

833 MPa

5.4%

373 MPa

980°C-24 h-HIP

99.9%

0.19%

20 µm

964 MPa

18.2%

530 MPa

980°C-48 h

98.3%

0.25%

23 µm

902 MPa

11.7%

478 MPa

980°C-96 h

98.8%

0.25%

25 µm

931 MPa

18.3%

475 MPa

Fine-1100°C

95.7%

0.22%

47 µm

907 MPa

4.7%

375 MPa

Fine-1100°C-HIP

100%

0.26%

75 µm

972 MPa

10.3%

403 MPa

Fine-1150°C

97.2%

0.31%

85 µm

937 MPa

4.9%

319 MPa

Fine-1230°C

97.5%

0.31%

118 µm

956 MPa

11.2%

328 MPa

Fine-1300°C

98.1%

0.26%

149 µm

977 MPa

14.0%

318 MPa

Fine-1300°C-HIP

99.9%

0.28%

171 µm

962 MPa

14.3%

340 MPa

Condition names

Table 2 Various properties of sintered and HIP treated compacts [1]

‘Typical’ MIM compacts had a large grain size of around 150 µm, whereas HDH-treated compacts showed very fine grain size. The tensile strength of most compacts satisfied the standard value for wrought material (over 895 MPa). Although most compacts showed sufficient elongation relative to wrought material (over 10%), the compacts with low relative density or treated by HDH showed relatively low elongation. The HDH-treated sintered compacts showed 470 MPa fatigue strength (rotating bend endurance limit). In addition, the compacts sintered at 980°C for 48 h had 478 MPa fatigue strength, the highest value among the sintered compacts. The compacts sintered at 980°C for 24 h and HIP treated showed 530 MPa fatigue strength, which is higher than the standard value of wrought material (510 MPa by ASTM Grade 5). The compacts, treated by HDH and HIP showed 635 MPa, the highest fatigue strength in HIP treated compacts. This value was twice as high as the fatigue strength of ‘typical’ MIM compacts.

IPF (Inverse Pore Figure) mapping images are shown in Fig. 3. ‘Typical’ MIM compacts showed coarse α colonies. HDH-treated compacts showed significantly fine equiaxed α +β microstructure. However, it was found that for HDH-treated material the prior β grains were very coarse, with the intercept method indicating a value of 801 µm in HDH compacts; this

was taken as being the cause of the observed low elongation levels in such compacts. The compacts sintered at 980°C in the α+β region showed equiaxed α grains. The fine powder compacts showed fine microstructure compared with typical metal injection moulded compacts, and the pore size was finer than that of normal powder compacts.

35µm µm µm 35 µm 3535 µm35 35 µm

Typical MIM(b) (b) HDH (c) 980 (a)(a) Typical MIM (b)HDH HDH Typical MIM (b)(b) HDH (c) 980 °C-24 hh h h (c)(c) °C-24 °980 C-24 hC-24 (a)(a) Typical MIM (b) HDH Typical MIM (a)(a) Typical MIM HDH (c) °hC-24 980 °C-24 (c) 980 °980

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Fig. 3 Inverse Pore Figure (IPF) mapping images of cross-sectional view of various compacts [1]

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Fatigue strength [MPa]

PIM at POWDERMET2018

750 700 650 600 550 500 450 400 350 300 250

as HIP treated

as sintered

0

0.1

0.2 0.3 0.4 0.5 1/grain diameter [ 1/µm]

0.6

0.7

Typical MIM Typical MIM-HIP HDH HDH-HIP 980℃-24h 980℃-24h-HIP 980℃-48h 980℃-96h Fine-1100℃ Fine-1100℃-HIP Fine-1150℃ Fine-1230℃ Fine-1300℃ Fine-1300℃-HIP wrought

Ratio of fatigue strength to HIP treated compacts [MPa/MPa]

Fig. 4 Relationship between grain diameter and fatigue strength. The fatigue strength of the sintered compacts sharply decreases due to grain refinement, unlike the tendency of the HIPed compacts [1] 1.1 1 0.9 0.8 0.7 0.6

Crack initiated from pore 0

5 10 15 Estimated value of pore dmax /grain diameter [µm/µm]

20

Typical MIM Typical MIM-HIP HDH HDH-HIP 980℃-24h 980℃-24h-HIP 980℃-48h 980℃-96h Fine-1100℃ Fine-1100℃-HIP Fine-1150℃ Fine-1230℃ Fine-1300℃ Fine-1300℃-HIP wrought

Ratio of fatigue strength to HIP treated compacts [MPa]

Fig. 5 Relationship between the ratio of maximum pore diameter to mean grain diameter and the ratio of fatigue strength compared to that of HIP treated compacts (Plotted points with arrows indicate that the failure started from a pore) [1] 1.1 1.05

1 0.95 0.9 0.85 0.8

95

96

97 98 Relative density [%]

99

100

Typical MIM Typical MIM-HIP 980℃-24h-HIP 980℃-96h Fine-1100℃ Fine-1100℃-HIP Fine-1150℃ Fine-1230℃ Fine-1300℃ Fine-1300℃-HIP wrought

Fig. 6 Relationship between relative density and ratio of fatigue strength compared to that of HIP treated compacts (These compacts have relative pore diameter <2) [1]

Fig. 4 demonstrates that the relationship between grain diameter and fatigue strength approximated to the Hall-Petch law. Wrought material had a fatigue strength of 725 MPa and a grain diameter of 2.5 µm and the as-HIPed compacts and the wrought material were observed to follow the same Hall-Petch line.

104

Next, the authors evaluated the relationship between “the ratio of maximum pore diameter to the grain diameter” and “the ratio of fatigue strength to that of HIP-treated compacts.” The results obtained are shown in Fig. 5. The plotted points with arrows indicate that failures initiated from pores. As the grain diameter decreases and the relative

Powder Injection Moulding International

September 2018

pore diameter (the ratio of maximum pore diameter to the grain diameter) becomes larger, the fatigue crack initiates from pores and the fatigue strength tends to decrease. Subsequently, a dominant factor for the region having a small pore diameter (relative pore diameter < 2) was considered. The relationship between relative density and ratio of fatigue strength is shown in Fig. 6. When relative density is decreased, the fatigue strength ratio tends to decrease. These results indicate that the fatigue strength is affected by relatively small pores. In summary, when the pore size is relatively large against the grain size, the largest pore acts as the defect that initiates a fatigue crack and significantly reduces the fatigue strength. When the pore size is relatively small against the grain size, the number of pores (relative density) reduces the fatigue strength even if the pores are small and of a low number, as seen in the MIM compacts.

Effect of particle size distribution and powder loading on the processing and properties of 17-4PH MIM feedstock Next, a paper from Shu-Hsu Hsieh, Chung-Huei Chueh and I-Shiuan Chen, Chenming Mold Ind. Corp. (UNEEC), Taiwan, and Martin Kearns, Paul Davies, Keith Murray and MaryKate Johnston, Sandvik Osprey Ltd., UK, considered the effects of particle size distribution and powder loading on the processing and properties of 17-4PH MIM feedstock [2]. The paper reported the results of a systematic study of the effects of particle size distribution on the sintering behaviour and final properties of 17-4PH. Various size fractions (90%-10 μm, 90%-22 μm and -32 μm) of gas atomised powder were extracted from the same production campaign and used for moulding test samples. These were sintered at a range of temperatures to study the densification process and to determine

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Particle Size Spec. min Spec. max

Fe Bal

PIM at POWDERMET2018

Cr

Ni

Cu

Nb

Mn

Si

C

S

P

O

N

15.5

3.0

3.0

0.15

-

-

-

-

-

-

-

17.5

5.0

5.0

0.45

1.00

1.00

0.07

0.03

0.04

-

-

90% - 10 μm

Bal

16.4

4.3

3.9

0.20

0.7

0.7

0.019

0.005

0.022

0.06

0.07

90% - 22 μm

Bal

16.4

4.0

4.0

0.21

0.5

0. 5

0.023

0.004

0.023

0.05

0.08

-32 μm

Bal

16.5

4.2

4.0

0.21

0.6

0.6

0.027

0.005

0.024

0.06

0.08

Table 3 17-4PH chemical specification and powder analysis [2]

Powder Size

D10, μm

D50, μm

D90, μm

Tap Dens, g/cm3

App. Dens, g/cm3

Pycno. Dens, g/cm3

90% - 10 μm

2.8

5.4

9.8

4.54

2.60

7.77

90% - 22 μm

4.0

10.3

21.1

4.76

3.10

7.80

-32 μm

5.8

13.5

28.5

4.76

3.50

7.80

Table 4 Particle size distribution data for test powders (Malvern Mastersizer 2000) [2]

the combined effects of particle size and sintering temperature on properties of interest. The 17-4PH powder used in this study was manufactured by Sandvik Osprey using its proprietary gas atomisation technology. Batches of powder were produced by induction melting of raw materials and atomisation using nitrogen gas. From the gas atomised powder, three different size fractions were extracted by sieving and air classification;

90%-10 μm

90%-22 μm

-32 μm

D10

2.8

4

5.8

D90

9.8

21.1

28.5

Sw

4.7

3.5

3.7

Table 5 Particle size distribution data and calculation of Sw [2] Also shown are apparent and tap density values (ASTM B527). There is a clear relationship between both apparent and tap density and the

“There is a clear relationship between both apparent and tap density and the powder size distribution, with finer powders showing lower density due to increased interparticle friction and less efficient particle packing.” -32 μm, 90% -22 μm and 90% -10 μm. The chemistry of each fraction was measured via ICP and Leco analysis and is shown, in Table 3, to conform to UNS S17400. Table 4 shows the particle size distribution data for each of these size fractions, as measured via laser diffractometry.

Vol. 12 No. 3 © 2018 Inovar Communications Ltd

powder size distribution, with finer powders showing lower density due to increased interparticle friction and less efficient particle packing. Feedstocks of the different 17-4PH gas atomised powders were compounded using a proprietary multi-component polyoxymethylene-

based (POM) binder system using a Z-Blade mixer. Feedstocks were made with different powder loadings in the range 56–65 vol.%. The mixing process involved high shear at 180°C for 2 h before granulating the feedstock. Disc specimens were prepared by injection moulding under various conditions. Moulded parts were then subjected to debinding in fuming nitric acid using a catalytic debinding furnace and sintering in an argon atmosphere using a vacuum furnace. Pore size and porosity variations were assessed by optical quantitative metallography analysis. Surface profilometry was used to measure the surface roughness, Ra, of sintered samples. The particle size distribution data shown in Table 4 were used to calculate the particle size distribution slope parameter (Sw) as follows: Sw = 2.56 / log (D90/ D10)

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PIM at POWDERMET2018

90 Injection Pressure (MPa)

80 70

60 50

90% -10 μm

40

90% -22 μm

30

-32 μm

20 10 0

56

59

62

65

Solid Loading (Vol.%)

Fig. 7 Injection pressures for 17-4PH feedstocks as a function of powder size and solid loading [2] 7.5 6.5 5.5 4.5

56 vol. %

3.5

59 vol. %

2.5

62 vol. % 65 vol. %

1.5 0.5 -0.5 4

5

6

7

8

9

Fig. 8 Melt viscosity vs shear rate and solids loading of 90% -10 μm 17-4PH [2] 7.8

Sintered Density (g/cm33)

Sintered Density (g/cm )

7.7 7.6 7.5 7.4 7.3

90% -10 μm

7.2

90% -22 μm

7.1 7

1260℃

1300℃

1330℃

1350℃

1380℃

Temperature, °C

Oversizing factor, OSF

Fig. 9 Relationship between density, powder size and sintering temperature [2]

Temperature, Temperature °C (℃)

Fig. 10 Relationship between oversize factor, powder size and sintering temperature [2]

106

Powder Injection Moulding International

September 2018

Atomised powders typically follow a log-normal size distribution and, therefore, the parameter Sw is the slope of the log-normal cumulative distribution and is similar to a coefficient of variation or standard deviation. A large Sw value implies a narrow particle size distribution and a small Sw value implies a wider distribution. Powders exhibiting Sw </=  2 (very broad distributions) are generally easier to mould, while Sw values between 4 and 5 signal difficulties in moulding and Sw values > 7 are the most difficult to mould. The Sw values shown in Table 5 suggest the 90% -22 μm fraction would exhibit the best mouldability, while the 90% -10 μm fraction would be the most difficult. The moulding/flow performances of the different feedstocks were assessed in different ways. Under identical conditions of temperature and feed rate, the real injection moulding pressure was determined. Fig. 7 shows the trend in injection pressure as a function of solids loading level for the three different particle size ranges. The figure shows that, at low powder loadings (< 60%), the injection pressure is independent of loading level and particle size. As the loading level rises, so the injection pressure increases and, moreover, there is a difference in the injection pressure with respect to particle size. Here, the 90% -10 μm powder exhibits the highest injection pressure, while the 90% -22 μm, the intermediate size, shows the lowest injection pressure. Fig. 8 shows an example of the melt viscosity vs shear rate behaviour of feedstocks, in this case for 90% -10 μm based feedstock. The family of curves shows the influence of increasing powder loading on increasing the melt viscosity at a given shear rate. In this case, the step from 62–65% loading has a particularly strong effect on increasing viscosity. Data were recorded at 190°C. Similar curves were derived for the other particle size ranges. Fig. 9 shows the effect of particle size distribution and sintering temperature in the range 1260–

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8.5

Pore Size, μm

8 7.5 7

Solid loading 62 vol% Solid loading 65 vol%

6.5 6

90% -10 μm

90% -22 μm Powder Size, μm

-32 μm

Fig. 11 Relationship between pore size, powder size and solid loading [2]

Porosity, %

2.00

Solid loading 62 vol%

Solid loading 65 vol%

1.50

1.00 0.50 0.00

90% -10 μm

90% -22 μm Particle size, μm

-32 μm

Fig. 12 Relationship between porosity, powder size, and solid loading [2] 0.140 0.120 0.100

No. 10-62

0.080

%C

1380°C on the density of sintered components with a starting powder loading level of 65%. It is evident that, as sintering temperature increases, the sintered density increases. It is also apparent that densification of the finer powder (90% -10 μm) begins at a lower temperature and leads to a significantly higher final density at temperatures below 1300°C. Sintered parts made with 90% -10 μm powders reach 7.6 g/cm3 at 1260°C while, above this temperature, the sintered densities achieved with different particle sizes tend to converge. In Fig. 10, the shrinkage behaviour is represented by the oversizing factor (OSF), again based on 65 vol.% solid loading in the same temperature range. At higher temperatures, the OSF increases, meaning that densification is more advanced at higher temperature. Therefore, whereas the sintered densities are the same, the OSFs are different, reflecting the different starting densities of the feedstocks. The authors concluded that this result is reasonable since, for a given solids loading, the increased powder surface area per unit mass associated with the finer powder requires a larger amount of binder, which therefore increases the shrinkage across the sintering temperature range. Fig. 11 shows the relationship between particle size range and pore size after sintering under the same conditions (1350°C). As the average particle size increases, the average residual pore size also increases. This trend is shown for the two highest powder loadings. The trend in absolute concentration of porosity is not so straightforward and Fig. 12 shows that the finer and coarser size distributions tend to give higher levels of porosity at the highest loading level and porosity levels are higher in absolute terms at the maximum loading level of 65%. In all cases, the absolute levels of porosity are low, but the 62% loading appears to yield the lowest absolute porosity with ~0.3% porosity for -32 μm powder. At equivalent sintering temperatures, the surface roughness of sintered specimens decreases with

PIM at POWDERMET2018

No.10-65

0.060

No. 22-62

0.040

No.22-65

0.020 0.000

1260℃

1300℃ 1330℃ 1350℃ Temperature (℃)

1380℃

Fig. 13 Final carbon content in sintered samples as a function of sintering temperature. Key notation refers to particle size and volume loading, so 10-62 means 90%-10 μm at 62% volume loading [2]

an increase in solids loading. For specimens with the same solids loading and sintering temperature, surface roughness depends on the size distribution of the metal powder in the feedstock, with finer powder giving the lower roughness values, achieving <0.3 µm Ra for 90%-10 µm. The fact that pore size increases with higher powder loading suggests that binder burn-out becomes

more difficult if the binder phase is no longer contiguous. The risk of incomplete burn-out increases, because there are fewer pathways for outward diffusion of pyrolysed binder constituents. This is consistent with absolute porosity levels being higher in parts made with highest powder loading and correlates with the trend in carbon content of the sintered parts shown in Fig. 13.

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Process parameter

Values

Mould temperature

60°C

Melt temperature

160°C

Ram position

25 mm

Injection velocity

120 mm/s

Packing pressure

40 MPa

Influence of feedstock property estimates and simulations on PIM of lead zirconate titanate (PZT) microarrays

Table 6 Process conditions for Powder Injection Moulding [3] Specific heat capacity, Cp (J/kg-K) Temperature (K)

Powder vol.%

0 (Binder)

52

283

2077

585

322

3360

853

352

3840

721

368

4894

1272

377

4639

613

407

3484

623

443

2528

635

Thermal conductivity (W/m·K) Temperature (K)

Powder vol.%

0 (Binder)

52

315

0.2

0.53

336

0.2

0.52

356

0.2

0.51

377

0.2

0.50

397

0.2

0.49

417

0.2

0.49

436

0.2

0.48

Table 7 Specific heat capacity and thermal conductivity values at various temperatures for feedstock with 52 vol.% PZT powder [3]

The authors drew the overall conclusion that the use of fine gas atomised metal powders in MIM products can deliver significant benefits over more conventional powder fractions in terms of superior surface finish and improved densification, provided that the powder volume loading is optimised. Finer powder fractions are therefore advantageous in special applications requiring precise dimensional control, thin-walled features and

108

excellent surface finish, where superior moulding characteristics are essential. Applications where these properties can be exploited include 3C devices requiring a highly polished finish and precision parts where coining steps may be avoided. However, it was also recognised that the coarser powders studied exhibited good moulding and sintering performance and that such powders can offer cost-effective solutions for a range of applications.

Powder Injection Moulding International

September 2018

The attention was then turned to Ceramic Injection Moulding in a paper presented by Kunal Kate, University of Louisville, Kentucky, USA, and co-authored by Bhusan Bandiwadekar and Sundar Atre, also of the University of Louisville; Jaeman Park, Joo Won Oh and Seong Jin Park, Pohang University of Science and Technology, Pohang, South Korea; and Anthony Yang, Moldex3D North America Inc, Detroit, Michigan, USA [3]. The paper discussed the influence of feedstock properties on the CIM processing of the widely used piezoelectric ceramic Lead Zirconate Titanate (PZT), with particular reference to its use in the numerical simulation of the injection process, and served as an update on a report from the earlier stages of the project presented at POWDERMET2017 and reviewed in Powder Injection Moulding International (Vol. 11, No.3, pp. 86-90). Whereas the 2017 report focused on a feedstock with 45 vol.% powder loading and the simulation of the moulding of a plain rectangular base plate, this update related to 52 vol.% powder loading in the feedstock and the moulding of a plate with an array of micro-pillar projections. Commercially available lead zirconate titanate (PZT) powder and a wax-polymer binder were used in feedstock development. The binder comprised paraffin wax, microcrystalline wax, carnauba wax, polypropylene, polyethylene and stearic acid. Maximum solids loading was determined for the PZT polymer composite using torque rheometry. Feedstock with 52 vol.% PZT content was developed. The CAD model of the moulded plate with micro-pillar projections was designed in SolidWorks, according to the experimental setup. The overall length was 37.50 mm, width

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18.75 mm and thickness 2 mm. The microarray was designed as a 3 x 3 configuration, with each micro-pillar having a length (l) of 1 mm and a diameter (d) of 0.19 mm. The aspect ratio (l/d) was 5.263. The CAD model was then imported into Moldex3D designer as a .step file. The model was meshed into 367,868 elements and had a mesh volume of 1.11 cm3. The PIM process parameters were as shown in Table 6. These values were used for PIM experiments and simulations. Material properties such as specific heat, thermal conductivity, specific volume and viscosity were estimated using semi-empirical formulae and feedstock models. Using these values, a material database file for 52 vol.% PZT was compiled in Moldex3D software. This material file, along with the process conditions, was used for performing simulations. Material properties were estimated for 52 vol.% PZT polymer composite using previously determined binder physical properties. Tables 7 and 8 summarise the estimated properties. The Cross-WLF model was used to find the fitting constants (Table 9), which are required for Moldex3D simulations. In order to check the effectiveness of PIM simulations in predicting mould filling behaviour, simulations were then performed on the meshed part file, using the material

Powder vol.%

Dual-domain Tait constants

0 (Binder)

52

336

335

b6, K/Pa

1.5 x 10-7

1.17 x 10-7

b1m, m3/kg

1.3 x 10-3

2.3 x 10-4

b2m, m3/kg∙K

1.3 x 10-6

1.26 x 10-7

b3m, Pa

1.3 x 108

7.34 x 108

b4m, K-1

6.0 x 10-3

5.0 x 10-4

b1s, m3/kg

1.2 x 10-3

2.28 x 10-4

b2s, m3/kg∙K

8.6 x 10-7

1.45 x 10-7

b3s, Pa

2.4 x 108

2.37 x 108

b4s, K-1

4.2 x 10-3

1.9 x 10-3

b7, m3/kg

8.5 x 10-5

5 x 10-6

b8, K-1

6.7 x 10-2

1.8 x 10-1

b9, Pa-1

1.4 x 10-8

2 x 10-8

b5, K

Table 8 Dual-domain Tait constants for binder and 52.vol.% PZT feedstock [3]

Cross-WLF constants

Powder vol.%

0 (Binder)

52

n

0.40

0.40

τ*, Pa

793

D1, Pa∙s

74145

4.29 x 10

23

2.28 x 1016

T*, K

333.00

372.08

A1

78.13

52.65

A2, K

51.60

51.60

Table 9 Viscosity constants [3]

Fig. 14 Mould filling behaviour in microarray [3]

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Fig. 15 Powder concentrations of filled and packed microarrays [3]

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Fig. 16 Powder concentrations within individual micro-pillars [3]

Fig. 17 (a) powder concentration of micro-pillar at location A1, (b) broken micro-pillar [3]

Fig. 18 Temperature during filling at bottom of micro-pillar [3]

database file and process conditions from experiments. The simulations successfully confirmed the mould filling behaviour with a 100% filled microarray. In simulations during mould filling, it was observed that the base plate was filled completely in the

110

x-y plane and, when the melt front hit the end of fill, the material was filled in the microarray pillars along the z direction (Fig. 14). Powder concentration in the feedstock was 90.6%. During injection moulding simulations, it was

Powder Injection Moulding International

September 2018

observed that the powder concentration varied from 87.6% to 91.7%. As seen in Fig. 15, powder concentration varied with the flow front, with green, yellow and red patches indicating variation in powder concentration. However, to understand the major variations in powder concentrations, a more detailed examination of the powder concentrations in the micro pillars was plotted in Fig. 16 This figure represents the powder concentration in each micro pillar and it can be observed that, on moving away from the gate location, the powder concentration becomes more uniform. It can also be implied that the micro pillar closest to the gate location has the highest amount of variation in powder concentration and the micro pillar furthest from the gate location has the least amount of variation. When the individual micro pillars were closely examined, a lower powder concentration was observed at the bottom of micro pillars, as shown in Fig. 17(a). The defect of a broken micro pillar during sintering, observed in Fig. 17(b), can be attributed to the variation in powder concentration seen during simulations. As the powder concentration at the bottom of micro pillar is less, it will lead to non-uniform shrinkage within the micro-pillar during debinding and sintering of the green body. This will result in neck formation in the region of low powder concentration and thus higher susceptibility to failure. More detailed study was performed as to the reason for the variation of powder concentration. In simulation, a cross section was taken at the region of low powder concentration (1.08 mm from bottom of base plate) to observe the temperature distribution in the microarray configuration during filling. This temperature during mould filling behaviour is represented in Fig. 18. It was observed that the temperature during filling varies with the location of the micro pillar from the gate location. The micro pillar closest to the gate location had the lowest filling temperature and the micro pillar farthest away from the gate location had the highest filling temperature.

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To understand this phenomenon further, mould filling temperature distribution within a micro pillar can be plotted in 3D against its x and y distance from the gate location. The graph observed was an inclined 3D surface, where, with increases in x and y distance, the temperature distribution within the micro pillar significantly increased. When the powder concentration was investigated at the same cross section, a similar 3D graph was plotted with powder concentration % on the z-axis, as shown in Fig. 19. The powder concentration of the PZT feedstock was 90.6%. The micro pillars with a filling temperature range from 80–90°C had a powder concentration of 87–88%; 90–100°C had a powder concentration of 88–90% and 100–130°C had a powder concentration of 90–91%. From these studies, it can be said that powder concentration is attributed to the mould filling temperature. The lower the mould filling temperature with respect to the average filling temperature, the lower the powder concentration. Similarly, a higher filling temperature will lead to more uniform powder concentration. Non-uniform powder concentration will cause various moulding defects such as distortion, cracks or voids. During PIM, these defects lead to non-uniform shrinkage or warping in the sintered parts. The PIM simulation results indicate that injection moulding behaviour predictions are comparable to the moulding behaviour in experiments. The weights of completely filled microarray parts from PIM experiments and simulation were 4.60 g and 4.62 g, respectively. Additionally, linear shrinkage prediction, with PIM simulations using estimated materials properties (1.38%), is comparable with PIM experiments (1.33%). Using simulations, defects and non-uniform shrinkage during sintering are predicted from knowledge of powder concentration and filling temperature of each micro-pillar.

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PIM at POWDERMET2018

Fig. 19 3D plot of % powder concentration with respect to distance from gate location [3]

References

Author

[1] The Effects of Grain Size and Pore Size on the High Cycle Fatigue Behavior of Injection Molded Ti-6Al-4V Compacts, Kentaro Kudo et al. As presented at the POWDERMET2018 International Conference on Powder Metallurgy & Particulate Materials, San Antonio, Texas, USA, from June 17–20, 2018, and published in the proceedings by the Metal Powder Industries Federation (MPIF).

Dr David Whittaker Tel: +44 1902 338498 Email: whittakerd4@gmail.com

[2] Effect of Particle Size Distribution and Powder Loading on Processing and Properties of 17-4PH MIM Feedstock, Shu-Hsu Hsieh et al. As presented at the POWDERMET2018 International Conference on Powder Metallurgy & Particulate Materials, San Antonio, Texas, USA, from June 17–20, 2018, and published in the proceedings by the Metal Powder Industries Federation (MPIF). [3] Influence of Feedstock Property Estimates and Simulations on Powder Injection Molding of Lead Zirconate Titanate (PZT) Microarrays, Bhushan Bandiwadekar et al. As presented at the POWDERMET2018 International Conference on Powder Metallurgy & Particulate Materials, San Antonio, Texas, USA, from June 17–20, 2018, and published in the proceedings by the Metal Powder Industries Federation (MPIF).

Proceedings Advances in Powder Metallurgy & Particulate Materials—2018, the proceedings of the technical sessions, poster program and special interest programs (where applicable), is published in digital format by the MPIF. These proceedings are provided to full-conference registrants free of charge or they can be purchased from the MPIF’s Publications Department. www.mpif.org

POWDERMET2019 POWDERMET2019, the International Conference on Powder Metallurgy & Particulate Materials, will take place in Phoenix, Arizona, from June 23–26, 2019. www.powdermet2019.org

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PM China & CCEC China & IACE China 2019 The 12th Shanghai International Exhibition for Powder Metallurgy, Cemented Carbides and Advanced Ceramics

2019.3.25~27 Shanghai World Expo Exhibition & Convention Center ORGANIZER

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Events

industry events 2018 IMTS2018 - International Manufacturing Technology Show September 10-15, Chicago, United States www.imts.com World PM2018 September 16-20, Beijing, China www.worldpm2018.com Euro PM2018 Congress & Exhibition October 14-18, Bilbao, Spain www.europm2018.com formnext 2018 November 13-16, Frankfurt, Germany www.formnext.com 36th Hagen Symposium November 30 - December 1, Hagen, Germany www.pulvermetallurgie.com

2019 APMA 2019 February 18-21, Pune, India www.apma2019.com MIM2019 February 25-27, Orlando, United States www.mim2019.org PM China 2019 March 25-27, Shanghai, China en.pmexchina.com

rapid + tct 2019 May 21-23, Detroit, United States www.rapid3devent.com POWDERMET2019 / AMPM2019 June 23-26, Phoenix, United States powdermet2019.org | ampm2019.org

Pick up your free copy at PIM related events worldwide PIM International magazine is exhibiting at and/or being distributed at events highlighted with the PIM International cover image.

Event listings and media partners If you would like to see your PIM/MIM/CIM related event listed in this magazine and on our websites, please contact Nick Williams, email: nick@inovar-communications.com We welcome enquiries regarding media partnerships and are always interested to discuss opportunities to cooperate with event organisers and associations worldwide.

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Ryer Inc.

Carbolite Gero Limited

21

Sandvik Osprey Ltd

17

Carpenter Powder Products

31

Silcon Plastic srl

35

Centorr Vacuum Industries, Inc

42

Sintex a/s

49

CM Furnaces Inc.

26

Sintez CIP Ltd.

16

TAV VACUUM FURNACES SPA

37

TempTAB

32

CN Innovations Holdings Ltd Cremer Thermoprozessanlagen GmbH

6 13

43 IFC

Digital Metal

4

United States Metal Powders, Inc.

51

Dynamic Group

7

USD Powder GmbH

20

Ecrimesa Group

30

Vibrom spol. s r.o.

39

Elnik Systems

14

Winkworth Machinery Ltd

29

eMBe Products & Service GmbH

55

Wittmann Battenfeld UK Ltd

41

9

XACT Wire EDM Corporation

53

Epson Atmix Corporation Erowa AG Euro PM2018

36 IBC

ExOne

59

formnext

60

Indo-US MIM Tec

47

IN(3D)USTRY 2018

82

Jiangxi Yuean Superfine Metal Co Ltd

33

Kerafol - Keramische Folien GmbH

18

LD Metal Powders 38

114

POWDERMET2019

99/113

Lide Powder Material Co,.Ltd

52

LÖMI GmbH

27

Malvern Panalytical Ltd

34

Matrix s.r.l.

19

Metal AM magazine

81

MIM2019

70

Ningbo Hiper Vacuum Technology Co Ltd

25

Powder Injection Moulding International

Advertise with us... Combining print and digital publishing for maximum exposure PIM International is the only business-to-business publication dedicated to reporting on the technical and commercial advances in MIM and CIM technology. Available in both print and digital formats, PIM International is the perfect platform to promote your company to a global audience. For more information contact Jon Craxford, Advertising Sales Director Tel: +44 207 1939 749 jon@inovar-communications.com

September 2018

© 2018 Inovar Communications Ltd

Vol. 12 No. 3


Developing the Powder Metallurgy Future

european powder metallurgy association

International Congress & Exhibition 14 - 18 October 2018 Bilbao Exhibition Centre (BEC) Bilbao, Spain

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Profile for Inovar Communications

PIM International September 2018  

Metal Injection Molding and Ceramic Injection Molding industry coverage from Powder Injection Moulding International magazine.

PIM International September 2018  

Metal Injection Molding and Ceramic Injection Molding industry coverage from Powder Injection Moulding International magazine.

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