ENGINEERING DESIGN MAY 2011 Innovative design solutions using DuPont high performance polymers in the industrial, consumer and energy sectors
WHERE ARE THE DESIGN ANSWERS? BY MARK YOUNG, EUROPEAN MANAGER FOR INDUSTRIAL, CONSUMER AND ENERGY APPLICATIONS Many times we ask ourselves how you, our customers, industry engineers, designers and managers, read Engineering Design magazine. Feedback we receive reassures us that it is appreciated, and read by a broad cross section of the engineering and design community. Yet we suspect it is valued very differently at an individual level – sometimes read in chunks during coffee breaks, sometimes from cover to cover, or sometimes it may just be a specific article that grabs your attention with the hope of providing a solution to your real and current design challenges.
If you are the kind of reader who just homes in on one article, we’d like to challenge you to read the others as well. It may seem at first glance that there is little relevance to your project or industry. However, what we continually find is that some of the best products , as well as the most apparently novel designs, are a direct result of taking ideas from one industry and transplanting Mark Young them into another, sometimes with just a small tweak to make them fit perfectly. Inside DuPont we call this “industrial cross-fertilization.” Each industry has different ideas, needs and applications for the use of raw materials, but those same ideas and solutions often have so much broader potential which can often go unnoticed. Our own engineers and development support team are doing just this – working with customers in many different fields and applying technologies or solutions from one industry to bring advantages to another.
THIS ISSUE AT A GLANCE
Take some of the stories in this issue of Engineering Design, for example. The Onzo Smart Energy Kit and the Autopen 2 both use DuPont™ Delrin® acetal resin for small mechanisms – the characteristics of Delrin® homopolymer give it significant advantages over copolymer, or any other polymer for that matter. When molded into small components, it provides
reliable mechanical performance – spring performance and creep resistance, low wear and low friction, quiet operation, precision and strength all in the smallest space possible. It’s all the kind of stuff that the consumer expects performancewise, but equally doesn’t want to have to think about. Reliability should be a given. Make the parts a bit bigger and they have the same reliable, accurate, low friction performance in the large molded bearings you will read about in the photovoltaic bearing article. As for another example, take the use of DuPont™ Zytel® HTN high performance polyamide in laptop covers. It replaces PC/ABS blends where a step change in performance is required. Unsurprisingly, the underlying requirements are familiar to many different industries – higher strength, higher stiffness, and lower weight to meet the demands of the next generation of product. So, in short, as you read through the magazine, we’d like to challenge you to read the articles in a new light. How can the solutions you see in these different industries be applied to your own industry and design problem? We’d also be very happy if we could work together with you on some of your challenges – by “cross fertilizing” the solutions we see from other industries to help solve your design and development material requirements. You can reach us on: plastics@dupont.com
• DuPont™ Delrin® in the Onzo Smart Energy Kit (page 3)
• DuPont™ Zytel® in the SonarBell® sonar responder (page 9)
• DuPont™ Delrin in the Autopen® insulin delivery device (page 4)
• DuPont™ Hytrel® and DuPont™ Crastin® in the Generation by Knoll® work chair (page 10)
• DuPont™ Zytel® HTN in handheld devices (page 6)
• DuPont™ Zytel® and DuPont™ Delrin® in photovoltaic applications (page 11)
• DuPont™ Delrin® in drivetrain transmission systems (page 8)
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A SMART MATERIAL FOR A SMART DEVICE BY IAN WANDS AND MARK HAZEL, DUPONT PERFORMANCE POLYMERS UK DuPont™ Delrin® acetal resin used for key components of the sensor included in the award-winning Onzo Smart Energy Kit, ensuring high accuracy, reliability and consistent operation.
The Onzo Smart Energy Kit is designed to put households in control of their energy use. It gives consumers real-time information about how much electricity they are using in their home and how much it is costing. By delivering actionable information that is easy to understand it helps them to learn how to manage their consumption, saving both energy and money.
The display shows users how much energy their home is using in real time, as well as contextualizing this information with targets and tools that help consumers understand their usage at a glance. The website allows users to dig deeper into how they use electricity and learn how they can reduce or change their consumption over time. It’s as part of the sensor’s unique clamp design that components molded from Delrin® acetal resin play an integral role in its attachment to the electricity meter and its ability to accurately read energy consumption. “The gray clip is fundamental to the simple and easy-to-use lock and release mechanism, which we purposely designed for single-handed use,” explains Jeremy Stimson, product design manager at Onzo Ltd, “while the spring inner ensures the constant contact between the two sections of the current transformer, the component that senses electricity consumption and converts it to a digital signal, which fits tightly around the electricity cable.” Indeed, it is the ability of the Delrin® spring to generate a consistently reliable force on the current transformer over time that is key to the long-term accuracy of the sensor. “DuPont
produced a stress analysis of the spring mechanism which showed that Delrin® acetal is able to outperform its competitors in terms of resistance to creep and stress relaxation, thereby extending the clamping force for this particular application,” confirms Stimson. A further quality of the Delrin® spring is its ability to cater for variations in size of the current transformer (CT). “The CT is a rough, metal component with wide tolerances. By choosing Delrin® we could be sure that there was enough flexural behavior in the springs to accommodate these differences in sizes,” continues Stimson. The integration of design features such as snap fits, hooks and catches in the Delrin® components helped Onzo eliminate the use of metal clips or hinges that would otherwise interfere with the wireless communication between the sensor and the display. The exclusion of metal components also means that the sensor, as well as the display, can be more easily recycled at the end of their useful lives. Launched in the UK in 2009 and a winner of the prestigious red dot award in the same year, the Onzo Smart Energy Kit is available free of charge to Scottish & Southern Energy (SSE) customers that sign up for its iplan energy scheme, or can be bought from Amazon in the UK.
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It works in three simple steps: 1) the sensor clips onto the live wire of the electricity meter, 2) it sends the amount of electricity being used in the home wirelessly to the display, 3) the display is connected to a computer to upload data, via USB, to a personalized website.
Onzo Ltd. 6 Great Newport Street, London WC2H 7JB Tel.: +44 (0) 20 3051 3270 hello@onzo.com, www.onzo.com PAGE 3
EFFORTLESS DELIVERY BY IAN WANDS, EUROPEAN HEALTH CARE SEGMENT LEADER AT DUPONT PERFORMANCE POLYMERS Specific grades of DuPont high performance polymers that meet demanding requirements for use in medical equipment enable the design and manufacture of reliable and durable products. This is illustrated by the recent launch of the Autopen® 2 insulin delivery device from Owen Mumford. It includes several functional components made of DuPont™ Delrin® acetal resin that are fundamental to its use for the effortless and accurate delivery of insulin to diabetes patients.
“However once a dose had been set by the user, it could not be reduced by winding the knob in the reverse direction and the user had to expel the set dose and redial. The design of the Autopen® 2 resolves this problem.” “Essentially a torsion spring is arranged within the housing to provide the drive force for ejecting medication from the insulin cartridge,” continues Mark Eaton. “The dose setting knob is coupled to both the spring and the housing in such a way that rotation of the knob relative to the housing results in compression of the spring. When the user applies a downward force on the trigger at the side of the pen, it releases the spring and a drive member is driven through the housing, expelling the required dose of insulin from the cartridge. In the event that a user oversets a dose, the button at the top of the dose setting knob, which is also coupled to the torsion spring, is used to unwind the spring in discrete steps with each press of the button.”
Delrin® key to successful development
Introduced during 2010, the Autopen® 2 constitutes a new generation of reusable pen injectors launched by Owen Mumford (Oxfordshire, England) under the Autopen® trademark that benefit from an automatic delivery system providing greater patient comfort and control. Its principal enhancement, beyond the ability to deliver a dose of up to 72 units of insulin in steps of one unit, is the integration of a patented mechanism that allows the user to correct the dose if it has been over dialed. “The original Autopen® incorporated a dose metering device, provided by a dose knob, that is rotatable to a position related to the dose of medication to be injected,” explains Mark Eaton, product designer at Owen Mumford. PAGE 4
The principal components behind the sophisticated mechanism used within the Autopen® 2 are molded from a range of grades of Delrin®. Required properties of the DuPont acetal resins include strength and stiffness, dimensional stability, fatigue resistance, low coefficient of friction and resistance to wear when used in intricate, geometrically advanced parts that, in many cases, move against each other or are required to snap fit together. For instance the locking bush, which is used to prevent the rotational movement of the leadscrew until delivery of the medication is triggered, is molded from a toughened grade of Delrin® due to the high torsional forces it must withstand, particularly during dose setting. It comprises a pair of fingers that engage with a corresponding channel within the leadscrew to prevent rotation during delivery. They are required to be flexible enough to flex outwards over ramps on the leadscrew when it is passed through the centre of the locking bush before snapping back to engage with the channels.
EFFORTLESS DELIVERY
Special Control grade of DuPont™ Zytel® nylon for collagen implant delivery device
rate dose delivery.” Rigorous and comprehensive testing confirmed the compliance of Autopen® 2 with the international standard ISO 11608 for pen-injectors.
The ChondroMimetic™ from TiGenix NV is marketed as a procedure pack with the collagen implant preloaded in an accurate, easy-to-use arthroscopic delivery device. A Special Control (SC) grade of DuPont™ Zytel® nylon was adopted for two of its component – the plunger and compressor fingers – each of which come into direct contact with the implant and are key to holding it in place and inserting it smoothly and accurately into the defect site. The DuPont material was specifically chosen for the stiffness and lowfriction behaviour of the plunger as well as providing the precise flexibility of the compressor fingers.
The Delrin® products were supplied to Owen Mumford by Distrupol, DuPont’s authorized distributor of its performance polymers in the UK. Both Distrupol and DuPont provided additional technical assistance with regard to reducing friction within the dose setting and delivery mechanism.
Alternatively, the dose knob is molded in a laser-markable grade of Delrin® for incorporation of the insulin measurements. It must also provide a robust surface for two sets of gear teeth within the part which works with the clutch collet and rewind button to allow the spring to unwind (as part of the dose correction procedure). A further five parts are molded from Delrin®, including the drive gear, rewind button, dose knob cover, ratchet drive shaft and cartridge compression cup. “Of all the plastic parts used within the Autopen® 2, seven are molded from Delrin® and they represent all of the mechanical and robust components fundamental to its operation,” confirms Mark Eaton. “We would not have been able to produce the Autopen® 2 without DuPont materials, the strength, dimensional stability and low wear/low friction of which are key to ensuring simple, reliable and accu-
DuPont offers one of the broadest portfolios of engineering plastics and thermoplastic elastomers for medical devices, surgical devices and for diagnostic or pharmaceutical manufacturing equipment. The DuPont health care product offering provides food agency compliance (EMSA and FDA), ISO 10993-5 and -11 compliance as well as USP Class VI compliance. Specialty health care products are manufactured following GMP. The specialty health care grades with regulatory support are available in two versions, each reflecting different levels of manufacturing control and material testing. Customers work with DuPont to identify the version that meets the needs of their specific application. Sixteen of the products are available as “special control” grades that meet very high standards of manufacturing consistency important for a wide range of non-implantable medical products. Twelve of the grades are available in “premium control” versions meeting requirements for even more demanding manufacturing controls, broader regulatory support, more testing, DMF access and the highest level of inspection.
http://healthcare.dupont.com Autopen® is a registered trademark of Owen Mumford Ltd.
CONTACT
ChondroMimetic™ is a trademark of TiGenix NV
DuPont: the material supplier of choice to the health care segment
Owen Mumford Ltd. Brook Hill, Woodstock, Oxfordshire, OX20 1TU, United Kingdom Tel.: +44 (0)1993 812021 info@owenmumford.co.uk www.owenmumford.com PAGE 5
ZYTEL® HTN: A MATERIAL OF CHOICE FOR HANDHELD DEVICES BY JERRY TSAI AND RUI ZHANG, DUPONT PERFORMANCE POLYMERS ASIA Engineering thermoplastics play an increasingly vital role in the production of electronic components and devices. Rather than seeking a one-size-fits-all solution, polymer producers such as DuPont are tailoring materials to the specific application with the goal of increasing performance and processing efficiency while lowering costs. One such product group is the DuPont™ Zytel® HTN family of semi-aromatic polyamides, which offers a combination of properties that make them ideal materials for use in handheld devices.
With built-in shielding, excellent flow, dimensional stability, toughness and strength, Zytel® HTN can reduce the total system cost of thinner and lighter housings for laptop computers, tablet PCs, cell phones and other devices. Zytel® HTN also delivers the right property set for the many electronic connectors, relays, light-emitting diode components and various other electrical and electronic parts contained within these devices. It can withstand high-temperature circuit assembly methods, including those using lead-free solder, has good strength, stiffness and toughness over a wide temperature and humidity range, and is now also available as a halogen-free grade providing conformity with recycling programs for discarded electronic products.
mately 17 GPa) and flexural strength (approximately 300 MPa) of Zytel® HTN makes it the material of choice for the production of these thinner, lighter and more costeffective covers.”
A thinner, lighter laptop housing A recent testimonial of the design flexibility afforded by Zytel® HTN in handheld devices is provided by the redesigned housing of the Lenovo IdeaPad U550. Weighing in at just 5.3 lbs (2.4 kgs) and measuring just over one inch (2.5 cm) in height, it is remarkably thin and light for a 15.6inch (40 cm) multimedia notebook. This is partly due to the use of a non-halogen, flame retardant grade of Zytel® HTN for the LCD rear cover assembly (the so-called A cover) and the bottom cover assembly (the D cover). Both covers had been previously produced using a polycarbonate (PC)/ acrylonitrile butadiene styrene (ABS) blend, but by changing to Zytel® HTN it has been possible to reduce their wall thickness from 1.8 mm – the thinnest thickness possible with PC/ABS – to 1.3 mm, a reduction of more than 25 percent. “Material stiffness is one of the critical requirements for the mechanical stability of a laptop’s A cover, which has to protect the sensitive electrical components inside the laptop as well as the LCD screen,” explains Aric Dai (Huafeng), research and development director of the IdeaPad product group at Lenovo. “The improved flexural modulus (approxiPAGE 6
Drop and pressure tests were used to confirm the protective attributes of the laptop housing, including the placing of loads of up to 25 kg (55 pounds) on the A cover. During hands-on consumer reviews, the laptop chassis and lid are described as exhibiting only mild flex when grabbed by the corners and twisted, whilst pushing on the back of the lid does not yield any ripples in the LCD screen – an impressive performance considering its reduced thickness. As well as improved strength, stiffness and impact resistance, the specified Zytel HTN® grade also demonstrates excellent flame retardancy. Whereas a UL-94 V0 rating at 0.8 mm was specified by Lenovo for the application, the halogenfree, flame retardant grade of Zytel® HTN achieves this at just 0.4 mm. The switch to Zytel® HTN also saw Lenovo adopt Rapid Heat Cycle Molding (RHCM) technology for the production of the highly visible covers. This process can be used to maximize the surface appearance of injection molded parts with a minimal effect on cycle time. Part costs can be reduced using this technology by eliminating the need for secondary operations to hide surface defects, whilst it can
ZYTEL® HTN: A MATERIAL OF CHOICE FOR HANDHELD DEVICES
As part of its technical assistance, DuPont provided recommendations on gate location in order to achieve lower filling pressure and improved cover flatness
Support in line with the customer's needs Comprehensive technical support by DuPont assisted Lenovo in its switch to the higher performance and more cost effective material solution, as Aric Dai of Lenovo recalls: “DuPont was able to offer a unique business package including access to its CAE capability during the design phase, onsite technical support, tool and customized gate design and mold-flow simulation, as well as a decoration solution which was in line with our design needs.” Indeed, patterns and texture are a defining element of the Lenovo IdeaPad aesthetic, and the U550 is no exception. An extremely fine checkerboard pattern molded onto the A cover makes it feel almost like the texture of knurled metal to the touch. The covers are painted and subsequent adhesion and warpage tests ensure conformity with production standards.
The Lenovo IdeaPad U550 with A and D covers molded from Zytel® HTN was developed in Asia at the end of 2009 and went into commercial production in China during May 2010. Further laptops within the Lenovo range are produced with either an A or D cover made with Zytel® HTN depending on design requirements. Members of the Design & User Experience team for the IdeaPad Product Group at Lenovo include Bulin Chen (designer), Zhensheng Wu (designer) and Detao You (material designer).
CONTACT
also be used to obtain glossy surfaces even with glass-filled materials. The adoption of RHCM technology was made possible by the higher glass transition temperature (around 115 °C or 240 °F) of Zytel® HTN than that of the previously used PC/ABS blend.
Dr. Ning Hao Designer, IdeaPad R&D, Lenovo No. 6 Shang Di West Road, Haidian District, Beijing, China Tel.: +86-10-58862089 haoning@lenovo.com PAGE 7
DRIVE YOUR IMAGINATION BY TIM BROGLA, PROGRAM DEVELOPER AT DUPONT PERFORMANCE POLYMERS An Ultra Light Urban Vehicle project at Bradley University shows how acetal gears – specifically gears made of DuPont™ Delrin® POM – offer strength, toughness and low-friction attributes needed to take the load, stress generated in drivetrain transmission systems while significantly damping noise and reducing weight inherent in metal gears.
The Ultra Light Urban Vehicle Project is the brainchild of Martin Morris, professor of mechanical engineering at Bradley University, Peoria, Illinois (US). The challenge to design and manufacture a zero-emissions vehicle began in 2006 and has evolved into a 3-wheeled vehicle licensed as a motorcycle that carries two people, baggage and weighs 430 lbs (195 kgs). It offers regenerative braking, a top speed of 45 mph (72 kmph) and a range of 40 miles (64 km) – the Bradley design team claims it costs 0.6 cents per mile to operate. Several gears used within the vehicle’s drivetrain transmission have been intricately produced using Delrin® acetal (POM) from DuPont Performance Polymers. Design and manufacturing support for the project was provided by Winzeler Gear, Harwood Heights, Illinois. The gears face conditions that traditional engineers may have previously considered off limits for standard acetal material, as Mike Cassata, design engineer at Winzeler Gear confirms: “The high-performance nature of a homopolymer acetal can manage the torque and load while delivering low friction and reduced noise.” He added that the planetary transmission gears of Delrin® POM must withstand the torque produced by a 25 horsepower motor @ 6,000 rpm. The gears can be machined from Delrin® bar or plate stock, significantly cutting cost and time while delivering
The drivetrain transmission uses several intricately machined gears that face conditions that traditional engineers may consider off limits for standard acetal material PAGE 8
mechanical properties comparable to the injection molded gears. “We can proceed from design to machined models in weeks, with a small tooling investment,” said Cassata. The successful use of Delrin® for gears in the Ultra Light Urban Vehicle goes some way to challenging the traditional preconception that POM is unable to withstand the harsh conditions associated with transmission applications. It is not difficult to imagine such gears being used in small engine transmissions such as those found in riding lawn mowers and golf carts. Indeed this will be the focus of the next generation of student design, where the young designers will be challenged to take even more weight and noise from the vehicle by using more Delrin® POM in the gears and housings. “As the world changes, we need to challenge many of our preconceived notions. We also need more whole brain, especially right brain, thinking to innovate,” concluded John Winzeler, president of Winzeler Gears and a fervent supporter of student challenges and art programs. “Student design challenges, such as the one initiated by Martin Morris at Bradley University, are great ways to challenge our prejudices and stimulate new ideas.”
SONAR TRANSPONDER RELIES ON DUPONT™ ZYTEL® BY IAN WELSH, SENIOR DEVELOPMENT SPECIALIST AT DUPONT PERFORMANCE POLYMERS UK The elegant use of materials, including DuPont™ Zytel® nylon, has helped revolutionize underwater subsea asset location and prevent marine mammals getting caught in nets.
To find equipment in anything but clear shallow water requires the use of sonar. Even with sonar, visualising the water column or sea bed is difficult and the industrial users of the ocean use powered transponders to locate key equipment. Such transponders are not only expensive but require regular routine maintenance depending on use and battery life.
How it works is largely down to the elegant use of materials technology for its construction. Looking very much like a bowling ball with diameters up to 200 mm, the SonarBell® has an outer shell made of DuPont™ Zytel® nylon and a core made of very soft silicon-based gel. The different acoustic qualities of the two materials used means that the sound waves from the received sonar signal travel faster round the Zytel® shell than through the silicon. This creates a constructive interference that delivers a return signal significantly higher than a hard reflecting sphere might otherwise deliver. It is omni-directional and is detectable by sonar in excess of 2 kilometers (1.2 miles) away depending on frequency of operation. The shell consists of two hemispherical parts, molded from Zytel®, that are currently joined by an adhesive, although spin welding is being investigated. The specific grade of material used was determined by the particularly demanding requirements of the design. As well as being able to withstand pressures of around 410 bars at depths of up to 4,100 meters (4,484 yards) the material also has to be impervious to moisture and possess specific sonar frequency properties. Providing ongoing support to SALT and its pro-
duction partners from its technical resources in the UK and Geneva, DuPont accompanied the development of the SonarBell® from its earliest prototype to the current production design. This included the provision of test samples and material data as well as guidance on mold and gate design. DuPont experts also recommended suitable spin welding designs and specific operating parameters to achieve optimum weld quality with Zytel®. The SonarBell® can be used in many market sectors: besides military use, the units can also be used to provide navigation lanes on the seabed or for keeping track of expensive subsea equipment. They can also mean fewer dolphins get caught in fishing nets, as Mr Tiltman, Chief Technical Office at SALT explains: “We can make the SonarBell® respond at an effective frequency that will allow the mammal to see the net much better using its sonar.” SonarBell® is a registered trademark of Subsea Asset Location Technologies Ltd.
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It is against this background that Subsea Asset Location Technologies (SALT) Ltd. of Salisbury (England) devised the concept for the SonarBell®, a passive sonar reflector which acts much as a ‘cats-eye’ does in the road. It takes in external energy and provides a strong ‘reflection’ in return, magnifying the original signal back to the searchers. This is achieved without the SonarBell® requiring an internal power source itself.
.Subsea Asset Location Technologies (SALT)Ltd. Upper Courtyard 2, Renshaw Barns, Upper Woodford, Salisbury, Wiltshire, SP4 6FA Tel.: +44(0) 1722 782856 Fax: +44(0) 1722 782856 info@cesalt.co.uk, www.cesalt.co.uk PAGE 9
A FLEXIBLE APPROACH TO WORK BY RICK TOBAR, GLOBAL FURNISHINGS SEGMENT LEADER AT DUPONT PERFORMANCE POLYMERS Designed by Formway Design of New Zealand, the Generation by Knoll® work chair offers a new level of comfort and unrestrained movement, supporting the range of postures and work styles typical of today’s dynamic workplace. The Generation chair takes the idea of elastic design – where a product rearranges itself in response to its user – to a new level. Using the inherent properties of DuPont™ high performance thermoplastics, Generation literally flexes as you change position, responding to your movements.
DuPont involvement in the Generation by Knoll® chair project from an early stage was fundamental to its award winning design. DuPont provided key input to Formway Design and Knoll that allowed them to envision the use of its materials in a way that had not been seen before in the furniture industry. The chair design leverages DuPont Performance Polymers for significant functional and structural components of the chair.
Material flexibility and durability Key to the chair’s flexing and supportive features is the use of the DuPont high performance thermoplastics DuPont™ Hytrel® TPC-ET and DuPont™ Crastin® PBT for key components of its design, the Flex Back and the Dynamic Suspension control.
The chair’s streamlined and innovative Dynamic Suspension control, which also uses Hytrel® and Crastin®, is a simple, nonmechanical control that provides a weight-compensated, smooth ride. Without the complexity of metal links or springs, the control uses one-third the number of parts of a traditional chair mechanism. The inherent properties of the materials – flexibility and durability – enable a range of energizing, multidirectional movements. “The materials give the Flex Back Net and the Dynamic Suspension control their elasticity and durability – so they essentially provide form and function, in one,” describes Pardo. With the materials providing both movement and structure, fewer parts and less energy are required to make the chair. As a result, at 37 lbs (17 kg), Generation is lighter than most high performance task chairs. PAGE 10
It is the first chair to be rated SMaRT© Sustainable Platinum, an achievement that reflects the Knoll commitment to integrating performance, quality and sustainability into its designs. This commitment is also reflected by ongoing development work between Knoll and DuPont on the use of renewablysourced materials in the chair. This year, the Flex Back Net will transition to Hytrel® that contains at least 50% renewably sourced ingredients by weight. Hytrel® RS grades create a smaller environmental footprint than the entirely petrochemically-based materials they replace without compromising performance. Overall, the Generation by Knoll® chair project constitutes a prime example of what we at DuPont call inclusive innovation, and it is a highly successful design story that is yet to be concluded. Generation by Knoll® is a registered trademark of Knoll, Inc.
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The frameless Flex Back design flexes as you move, with the Flex Back Net cradling your back and the unique figure 8 structure enabling multidimensional movement. “The Flex Back Net is fused to the figure 8 structure, yet to identify one component as the skin and the other as the skeleton would be misleading, as they are inextricably intertwined,” explains Benjamin Pardo, Knoll design director.
Knoll, Inc. 1235 Water Street, East Greenville, PA 18041 Tel.: +1 215 679-7991 info@knoll.com, www.sithowyouwant.com
NEW DEVELOPMENTS FOR THE PHOTOVOLTAIC INDUSTRY BY ORVAR OTTERSTEDT, PV MARKET DEVELOPMENT MANAGER AT DUPONT PERFORMANCE POLYMERS DuPont materials have been used in the photovoltaic industry for more than 30 years. Amongst recent applications are the development of a cover for an inverter module, made from a special, flame-retardant grade of DuPont™ Zytel® PA66/6 copolymer, and bearings used solar tracking systems, made from a particularly low wear/low friction grade of DuPont™ Delrin® acetal resin.
The inverter module is at the heart of a photovoltaic system: it converts direct current produced by the solar modules into alternating current, which is subsequently fed into the national grid. Its housing is usually made of metal due to the high requirements in terms of dielectric strength and fire safety that apply to such an application. However, in the latest generation of ‘Sunny Boy’ inverters from SMA Solar Technology AG, Niestetal (Germany), a Bluetooth interface is used to enable wireless communication with the photovoltaic system. Because metal is impenetrable for radio waves, the company sought to develop a polymer cover for the lower section of the housing where the switch disconnector, the electronic display unit and the radio module are located. The material used to produce the cover (see image right, black section of inverter module cover) is a special, flameretardant grade of DuPont™ Zytel® PA66/6 copolymer with a 25 wt. % glass fiber reinforcement. With a CTI value (CTI = Comparative Tracking Index) of 325 V, a GWFI value (GWFI = Glow Wire Flammability Index) of 906 °C and classified with the UL94 V-0 flammability standard, it meets high dielectric strength and fire safety requirement. The specified Zytel® grade also provides very high mechanical strength and stiffness as well as high dimensional stability. The material’s low tendency for warpage or shrinkage during injection molding, combined with structural enhancements such as reinforcing ribs, enable compliance with even the tightest of manufacturing tolerances. This ensures a high accuracy of fit with the other housing section made of cast aluminum. Moreover, the use of Zytel® ensures a high surface quality for the visible component.
Low friction and low maintenance polymer bearings In Majadas de Tiétar, Spain, bearings made from a particularly low wear/low friction grade of DuPont™ Delrin® acetal resin support a total of 192,000 parabolic mirrors at a solar thermal power plant belonging to ACCIONA Energía S.A.
The material possesses a very low dynamic coefficient of friction of 0.13 (standard grade: 0.35), enabling the reliable, smooth and millimetre-precise positioning of the hydraulically-operated mirrors in accordance with the sun’s movement. Consequently, this helps further improve the plant’s overall effectiveness. Thanks to the high wear resistance of the material, maintenance costs over the entire lifetime of the plant are reduced when compared to steel bearings. This ultimately helps reduce total operating costs and thereby the cost of energy production. ACCIONA Energía is one of the global leaders in the production of solar thermal power plants. The company currently operates three plants in Spain and one in Nevada/USA with an overall capacity of 214 MW. The 50 MW solar thermal power plant in Majadas de Tiétar supplies 32,000 households with environmentally-friendly power. When compared to a traditional coal-fired power station, the solar thermal power plant contributes to an annual saving of approximately 100,000 t CO . 2
http://photovoltaics.dupont.com PAGE 11
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Schweiz / Suisse / Svizzera Biesterfeld Plastic Suisse GmbH Dufourstrasse 21, Postfach 14695 CH-4010 Basel Tel. +41 61 201 31 50, Fax +41 61 201 31 69
España Du Pont Ibérica S.L., Edificio L’Illa Avda. Diagonal 561, E-08029 Barcelona Tel. +34 93 227 60 00, Fax +34 93 227 62 00
Slovenija Serviced by Biesterfeld Interowa GmbH & Co. KG. See under Österreich.
France Du Pont de Nemours (France) S.A.S. Défense Plaza, 23/25, rue Delarivière-Lefoullon La Défense 9, F-92800 Puteaux Tel. +33 1 41 97 44 00, Fax +33 1 47 53 09 67
Suomi / Finland Du Pont Suomi Oy PO Box 54 (Keilaranta 12) FIN-02150 Espoo Tel. +358 207 890 500, Fax +358 207 890 501
Hellas Biesterfeld Hellas Intralink S.A. Trading Establishmen 149, AG. Triados Menidi Acharnes GR-13671 Athens Tel. +30 210 24 02 900, Fax +30 210 24 02 141
Sverige Serviced by Du Pont Danmark ApS. See under Danmark.
Israël Gadot Chemical Terminals (1985) Ltd. 16 Habonim Street, Netanya - South Ind. Zone IL-42504 Netanya Tel. +972 9 892 95 52, Fax +972 9 865 33 81 Italia DuPont de Nemours Italiana S.r.L. Centro Direzionale “Villa Fiorita” Via Piero Gobetti, 2/C, I-20063 Cernusco s/N (MI) Tel. +39 02 92629.1 (switchboard) Fax +39 02 92107755 Magyarország DuPont Magyarország Kft. Neuman Janos u.1, HU-2040 Budaörs Tel. +36 23 509 400, Fax +36 23 509 432 Maroc Serviced by Biesterfeld Iberica S.L. see under Portugal Norway / Norge Distrupol Nordic Ostenssjoveien 36, N-0677 Oslo Tel. +47 23 16 80 62, Fax +47 23 16 80 62 Österreich Biesterfeld Interowa GmbH & Co. KG Bräuhausgasse 3-5, P.O. Box 19, A-1051 Wien Tel. +43 1 512 35 71-0, Fax +43 1 512 35 72-100 info@interowa.at, www.interowa.at Polska Du Pont Poland Sp. z o.o. ul. Powazkowska 44C, PL-01-797 Warsaw Tel. +48 22 320 0900, Fax +48 22 320 0910
Türkiye Du Pont Products S.A. Buyukdere Caddesi No. 122 Ozsezen Ismerkezi,A block, Kat: 3 Esentepe, 34394 Istanbul, Turkey Tel. +90 212 340 0400, Fax +90 212 340 0430 Ukraine DuPont Ukraine LLC Representative Office Business center "Podil Plaza" 30a, Spaska Street, Kyiv 04070 Tel. +380 44 4952670, Fax +380 44 4952671 United Kingdom Du Pont (U.K.) Limited Wedgwood Way Stevenage Herts, SG1 4QN Tel. +44 14 38 73 40 00, Fax +44 14 38 73 41 09 South Africa DuPont de Nemours Société Anonyme South African Branch Office 4th floor Outspan House 1006 Lenchen Avenue North Centurion, Pretoria 0046 Tel. +27 12 683 5600, Fax +27 12 683 5661 Requests for further information from countries not listed above should be sent to: Du Pont de Nemours International S.A. 2, chemin du Pavillon CH-1218 Le Grand-Saconnex/Geneva Tel. +41 22 717 51 11, Fax +41 22 717 52 00
Engineering Design is published in English, French, German, Italian, Russian and Spanish by Du Pont de Nemours International S.A. P.O.Box 50, CH-1218 Le Grand-Saconnex, Geneva, Switzerland.
Canada E.I. du Pont Canada Company Box 2200, Streetsville Mississauga, Ontario, L5M 2H3 Tel. +1 905-821-5193, +1-800-387-2122 Fax +1 905 821 5057 Information@can.dupont.com Mexico DuPont S.A. de C.V. Homero 206 Col. Chapultepec Morales 11570 Mexico D.F. Tel. +525 722 1208, Fax +525 722 1454 SOUTH AMERICA Argentina Du Pont Argentina S.A., Avda. Mitre y Calle 5 (B1880EED) Berazategui-Bs.As. Tel. +54 11 4239 3865, Fax +54 11 4239 3817 Brasil DuPont do Brasil S.A. Al. Itapecuru, 506 Alphaville 06454-080 Barueri-Sao Paulo Tel. +55 11 4166 8299, Fax +55 11 4166 8513 ASIA-PACIFIC Australia DuPont (Australia) Ltd. Level 16, 168 Walker Street, North Sydney NSW 2060, Australia Tel. +61 2 9923 6111, Fax +61 2 9923 6011 China Beijing Du Pont China Holding Co., Ltd. 18/F, Tower A, Gemdale Plaza No. 91 Jianguo Road, Chaoyang District, Beijing 100022, P.R. China Tel. +86-10-8557-1000, Fax +86-10-8557-1888, 8557-1999 China Shanghai DuPont (China) Research & Development and Management Co., Ltd. No. 600, Cailun Road, Zhangjiang Hi-Tech Park, Pudong New District, Shanghai 201210, P.R. China Tel. +86-21-2892-1000, Fax +86-21-2892-1234 DuPont China Holding Co. Ltd., Shanghai Branch 399 Keyuan Road, Bldg. 11 Zhangjiang Hi-Tech Park Pudong New District, Shanghai 201203, P.R. China Tel. +86-21-3862-2888, Fax +86-21-3862-2889
L-14583
Korea DuPont (Korea) Inc. 3-5th Floor, Asia Tower #726, Yeoksam-dong, Kangnam-Ku Seoul 135-082, Korea Tel. +82-2-2222 5200, Fax. +82-2-2222 5470 New Zealand DuPont (New Zealand) Ltd. 98 Kerrs Road, Manukau City Auckland, New Zealand Tel. +64-9 268 5500, Fax +64-9 268 5490 Malaysia DuPont Far East Inc. 6th Floor, Wisma Samudra, No. 1, Jln. Kontraktor U1/14, Hicom-Glenmarie Ind. Park, 40150 Shah Alam, Selangor, Malaysia Tel. +60-3-5569-3006, Fax +60-3-5569-3001 Pakistan DuPont Pakistan Operations (Pvt) Ltd. Bahria Complex I, 2nd Floor MT Khan Road Karachi 74000, Pakistan Tel. +92-21 561 1110, Fax +92-21 561 1430 Philippines DuPont Far East Inc. 8/F., Solid Bank Building 777 Paseo de Roxas 1226 Makati City, Philippines Tel. +63-2 818 9911, Fax +63-2 818 9659 Singapore DuPont Company (S) Pte Ltd 1 HarbourFront Place #11-01 HarbourFront Tower One, Singapore 098633 Tel. +65 6586 3688, Fax +65 6272 7494 Taiwan DuPont Taiwan Ltd. 13/F., No. 167, Tun Hua North Road Taipei 10590, Taiwan Tel. +886-2 2719 1999, Fax +886-2 2719 0852
China Shenzhen Du Pont China Holding Co., Ltd. Chegongmiao Industrial Area, District No. 5 Shenzhen, Guangdong 518040, P.R. China Tel. +86-755-8330-7848, Fax +86-755-8340-0760
Thailand DuPont (Thailand) Limited 6-7th Floor, M. Thai Tower All Seasons Place, 87 Wireless Road Lumpini, Phatumwan Bangkok 10330, Thailand Tel. +66-2 659 4000, Fax +66-2 659 4001
Japan DuPont Kabushiki Kaisha Sanno Park Tower, 11-1 Nagata-cho 2-chome Chiyoda-ku, Tokyo 100-6111, Japan Tel. +81-3 5521 8500, Fax +81-3 5521 2595
Vietnam DuPont Far East Inc. 12th Floor, Central Plaza Building, 17 Le Duan Blvd., District 1, Ho Chi Minh City, Vietnam Tel. +84-8 824 3192, Fax +84-8 824 3191
Publisher:
The information set forth herein is furnished free of charge and is based on technical data that Contact: DuPont believes to be reliable. It is intended for use by persons having technical skill at their own discretion and risk. DuPont makes no warranties, express or implied, and assumes no liability in connection with any use of this information. Editor: © 2011 E.I. du Pont de Nemours and Company The DuPont Oval Logo, DuPont™, The miracles of science™ and all products denoted with ® or ™ are registered trademarks or trademarks of E. I. du Pont de Nemours and Company or its affiliates.
Indonesia DuPont Far East Inc. Menara Mulia, Suite 501 Jl. Jend. Gatot Subroto Kav 9 - 11 Jakarta 12930, Indonesia Tel. +62-21 522 2555, Fax +62-21 522 2565
Layout:
Du Pont International Operations Sarl DuPont Performance Polymers 2, ch. du Pavillon, CH-1218 Le Grand-Saconnex, Geneva Switzerland Tel.: +41 22 717 51 11, Fax: +41 22 580 22 35 Rémi Daneyrole remi.daneyrole@dupont.com Andrew Wilkins PR andrew.wilkins@btconnect.com Konsens PR GmbH & Co. KG mail@konsens.de
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