RCE - Advanced Engineering 2013

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Advanced Engineering

2013

Red Bull’s manufacturing advantage revealed

3D printing in motorsport

State of the art composites

TECHNOLOGY - RAPID PROTOTYPING

Fast access

to essential parts Modern 3D printing and prototyping systems are making key components and prototypes available in a matter of hours – a godsend for the racing industry

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apid prototyping was the term given in 1986 to the process of transforming a virtual computer model directly into a physical 3D object that you could hold in your hand. The only company in the market at the time was 3D Systems, who used a laser to change a photopolymer from liquid to solid in a process called stereolithography.

SLA is the acronym for stereolithography apparatus.

Since then we have had other companies and other processes entering the market; Selective Laser Sintering (SLS) from EOS and Fused Deposition Modelling (FDM) from Stratasys. These have introduced new materials and because the components made by these processes were made from ‘normal’ materials like nylon and aluminium. This has given rise to the term rapid manufacturing (RM), as the components can be used straight from the rapid prototyping machine. RM has variously been referred to as desktop manufacture (DTM), but now the commonly accepted term for the whole technology from rapid prototyping to rapid manufacturing is additive manufacture (AM).

Then, with companies like Z-Corp and Objet entering the market, along came 3D printing in the late-90s. The term 3D printing – otherwise known as solid imaging – was coined because these technologies used a printing head much like an inkjet printer head to create the objects, rather than a laser in a solidifying or melting process.

With the move to 3D printing, there was an effort to bring the process from the workshop into the office and even into DIY or

by CHARLES CLARKE domestic use, the idea being that you would have a 3D printer on your desk alongside your 2D one. Prior to the modern 3D printing movement, all these AM technologies were industrial or semi-industrial processes.

Now there are growing numbers of parts on F1 cars and in other formulae made using AM techniques. In order to save space, much of the pipework for the McLaren F-duct was made this way. The beauty of this technique is that it can make parts with infinitely variable geometry that are impossible to make by any other more traditional manufacturing process.

CRP Technology is a leading producer of the Windform materials and constructor of AM parts for the racing industry. It has offices in Modena, Italy and Mooresville in North Carolina.

'We’ve had rapid prototyping since the mid-80s, but now there’s a strong movement towards using the technology for rapid manufacture,' says Franco Cevolini, Group CEO and technical director of CRP. 'This is particularly the case in racecar situations where the speed of manufacture helps to get the racecar to the track as quickly as possible.

'Rapid manufacturing techniques are widely used in F1, and CRP has two different kinds of technologies,' continues Cevolini. 'There is the technology for plastic composite parts along the lines of our Windform materials, and now we can also make metal parts.'

The composite parts are mainly used for aerodynamic features and cooling systems,

www.racecar-engineering.com • Advanced Engineering supplement

brake ducts and for other cooling ducting for keeping various components like the clutch or electronic systems at their preferred operating temperature.

'It’s also very important to have the right cooling for the new turbo engines in F1 next year,' says Cevolini. 'These engines need to be fitted with a thermal energy recovery system [TERS] that converts the heat generated and usually wasted by the turbocharger into electrical energy, so efficient ducting will be crucial.

'We use SLS, which is a very free and flexible technology compared to other 3D printing technologies like SLA or FDM. With SLA and FDM you are limited by the fact that the model must be supported while it’s being generated. With SLS, the model is submerged in a container full of unsintered powder or metal granules that support the 3D object during manufacture.'

At CRP they also have two technologies for the production of metal parts: Direct Metal Laser Sintering (DMLS) and Electron

Advances in rapid prototyping technology mean that parts and scale models can be produced quickly and efficiently

IMAGES COURTESY OF TOYOTA MOTORSPORT GmbH

Beam Melting (EBM). In both cases, metal powder is melted using lasers or electron beams.

These are quite new technologies that have yet to reach their full potential, compared with the other AM processes.

Consequently, the process is quite slow and the machines are quite small, so you are currently restricted to making smaller parts.

'We produced a number of roll hoops using EBM technology and titanium,' says Cevolini.

'Inside the snorkel air scoop

on an F1 car there is usually a metal or carbon fibre structure that transmits the load of the car, should the car turn upside down and so protect the driver.

This roll hoop structure is subject to rigorous FIA testing, so the ability to generate it using rapid prototyping is very beneficial.

Also, the roll hoop is mounted very high on the vehicle, so to minimise its inertia it needs to be made as light as possible. With rapid prototyping technology, it’s possible to make structures

with complex internal voids or honeycomb-like strengthening.

These internal structures cannot be made by any other process, so weight for weight a rapid prototyped roll hoop is far stronger than a fabricated one. Using EBM technology it’s possible to make the whole roll hoop in titanium.'

Very little additional finishing is required other than tidying the component and milling the location lugs. It can then be bonded to the rest of the chassis

and subjected to the FIA test.

Taking this technology to the extreme – and with the future availability of larger machines – it should be possible to make a suspension upright this way.

However, the FIA decreed in the new rules that all uprights should be CNC machined from solid aluminium, so here we have a technology that could potentially reduce the cost of a fairly expensive component, but it can’t be used because of the FIA rules.

Advanced Engineering supplement • www.racecar-engineering.com

TECHNOLOGY - RAPID PROTOTYPING 'We started to develop the Windform rapid prototyping materials specifically for motorsport applications,' says Cevolini. 'When we started with rapid prototyping in 1996, we recognised its potential, but there were a lot of limitations from a motorsport point of view, because of the kind of materials that were available at the time.

So we started to develop our own and Windform was born.'

These materials are now widely available, and since CRP’s recent Nasa accreditation they can also be used for aerospace components.

'Every time we develop a new material, we start by maximising its mechanical properties, its strength, abrasion resistance and durability, and now with the new requirements of F1, we’re looking particularly at improving the thermal properties of the material,' says Cevolini. 'We already have applications where temperature is an issue, and so we are working to improve the heat resistance of our materials.

With the new regulations in F1 governing the V6 turbo engines, there will be lots of heat issues in relation to ducting and bodywork.

'If you look at the calendar for F1, there is often not a lot of time between races, so all our F1 customers are coming to us asking for race-ready parts straight from the rapid prototyping process. The expectation from them is to find a technology that can produce parts quickly that will fit straight on to the car. They should not involve any other process, other than minimal hand finishing and fitting. Rapid casting, or RIM casting, is now too slow for F1.

'What I see for the very near future is a need to improve the reliability and speed of the machines and to develop machines that produce more production-ready parts, rather than prototypes. We also need machines that can make bigger AM parts from "real world" materials quickly without the need for any complex finishing process.'

The history of rapid manufacturing at Enstone began in 1998, when the first 3D Systems SLA 5000 was installed for rapid prototyping. This

In practical terms, the Lotus F1 Team can not only test more than 600 components per week in the wind tunnel, but also build some racecar parts directly from digital data using CAD and SLS technology. Using SLS, complex car components are produced in hours rather than weeks, and in some cases the part is ready for inspection before the drawing has even passed through the system.

The Lotus F1 Team’s ultimate goal is to use digital manufacturing as a fully industrialised technology to deliver race-ready car parts in volume to reduce cycle time and cost. Lotus is looking forward to the development of materials by 3D Systems that can withstand the intense temperatures – around 250degC – found in an F1 car.

Pratt and Miller used a 3D ZPrinter to create a model of their GTE car, but quickly adapted to developing moulds for carbon fibre parts

machine was originally acquired to assist the packaging of the racecar – getting everything to fit within the tight confines of the aerodynamic surfaces. Very soon its potential to assist in the wind tunnel was noticed by the aerodynamicists of the then Benetton F1 team when they saw the complexity and quality of the components coming from the SLA 5000.

'Once the team got their first 3D Systems machine, they used it to develop component prototypes with a size/fit function,' says Dirk de Beer, head of aerodynamics at Lotus F1. 'It then gradually expanded from rapid prototyping to wind tunnel model manufacturing, allowing our aero department to grow from 11 to 80 employees. In wind tunnel testing, aerodynamics is an empirical science. We design and compare new ideas

and choose directions to follow.

The more ideas we can compare and evaluate, the more successful we will be on the track.

'The car model in the wind tunnel features a complex network of pressure sensors.

These were positioned by drilling pressure tappings into metal and carbon fibre components before SLA technologies became available. The ability to produce complex AM solids with intricate internal channels has revolutionised our ability to place these sensors and increase their numbers. It’s a dream come true for aerodynamicists!'

Lotus now has nine of these machines – five SLA iPro 8000 systems, one SLA 7000, one Sinterstation Pro 140 SLS system and two Sinterstation HiQ SLS systems – which today allow direct manufacture of production parts for the racecars.

"All our F1 customers are coming to us asking for parts straight from the rapid prototyping process"

www.racecar-engineering.com • Advanced Engineering supplement

machine heads Joe Gibbs Racing (JGR) has 70 cars running in NASCAR and other series. It boasts a machine shop of 15 CNC machines, busy round the clock making parts for all the cars. It was tough to get machine time for prototyping, and a five-week backlog left new designs stuck in the concept phase longer than desired.

At JGR, new design concepts must balance weight reduction, power increase and control with handling improvement, while adhering to NASCAR’s rules. This yields extremely complex part designs. 'When milling these prototypes, we could have as many as seven machine setups.

This was an inefficient use of our machines and manpower,' says Mark Bringle of JGR. 'A prototyping system can make these complex parts in one operation, and it doesn’t require CAM programming.

'We evaluated nine prototyping technologies, but settled on the Stratasys Fortus fused deposition modelling process for two reasons. FDM didn’t require any facility modifications, and because we wanted to model with the strong thermoplastics available for FDM – polycarbonate and polyphenylsulfone. We can build prototypes tough enough to bolt on to the car, even the engine block, and they can take the heat.

'With our FDM machine, we can start building new concepts 15 minutes after CAD work is

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TECHNOLOGY - RAPID PROTOTYPING complete, and prototypes are ready within a day. Previously, prototyping took a minimum of a week, and the delays became longer when the inevitable design changes occurred. Now, with the FDM machine, we make the changes and build another prototype immediately.'

After only a few months of prototyping, JGR cleared its backlog of new design concepts. 'The FDM process allows our engineering team to get great ideas on to the cars quickly,' says Bringle. 'This has been a big factor in our success and FDM has permanently changed the way we do business. The drivers, the crew chiefs and the chief designer are all amazed, even slack-jawed, at what we can do with FDM and how it has changed our process.'

Toyota Motorsport GmbH (TMG), in Cologne has one of Europe’s largest concentrations of rapid manufacturing machines under one roof. It boasts 10 stereolithography machines (SLA 5000 and SLA 7000 units) and two large-frame laser sintering machines (P700 and P360 units).

This flexible and adaptable technology allows even the most complex objects to be produced as single structures, whether for use as finished parts or wind tunnel models.

TMG’s rapid manufacturing systems make as many as 2,000 unique parts a month at peak season. 'No matter where you are in the world, production can begin on your part at TMG within just a few hours of receiving a suitably detailed 3D CAD model or STL file. Then we can quickly turn your innovation into reality,' says Alastair Moffitt of TMG. 'And you can be sure of a smooth and trouble-free process thanks to our machines, which allow round-the-clock supervision and instant reaction to any problems.

Utilising video and internet technology, we can make part production faster and more reliable than ever before.'

Pratt & Miller has developed many race programmes, including Corvette Racing, the most successful team in the history of the ALMS. They originally got their full colour 3D ZPrinter (3D Systems) for marketing

Thermoplastics have developed sufficiently to allow heat-sensitive areas of the car, including the engine block, to be created using FDM

purposes to communicate their capabilities and boost enthusiasm for their products.

They soon discovered that they could use the ZPrinter to create wax infiltration moulds for carbon fibre part production. The moulds not only work remarkably well with wax infiltration to produce accurate parts with smooth surfaces, but they can be used for multiple runs.

This unexpected reusability translates into time and materials, saving on moulds and reprinting. This helps teams to focus their energies on more creative designs.

The success of wax infiltration moulds led to yet another innovation in the form of lost mould casting, which has enabled Pratt & Miller teams to achieve extremely complex parts with fully smooth interior surfaces, enhancing airflow.

Effective methods such as these are a tremendous part of the ZPrinter’s contribution to Pratt & Miller, enabling the engineering house to produce racecars more quickly. The ZPrinter saves time, and has increased profitability. 'It’s ideal for what we’re trying to achieve,' says lead design engineer Gary Latham.

Laser Lines Ltd, based in Banbury, has been involved with Stratasys and rapid prototyping for over 20 years. One of the largest applications to emerge is the use of FDM technology to produce soluble core mandrels to aid the manufacture of carbon composite components such as ducts and fluid pipes. The main challenge here was utilising both the equipment and operating software for an application it was not initially designed for. The use of FDM SR-30 soluble cores

"Drivers, crew chiefs and the chief designer are all slack-jawed at what we're able to do with FDM"

www.racecar-engineering.com • Advanced Engineering supplement

has now been adopted by many of the top F1 teams.

The Stratasys FDM technology builds parts in engineering grade thermoplastic materials. Although not normally associated with high performance, many companies have exploited both novel and demanding uses for AM parts, with many examples of FDM ULTEM-9085 components being installed directly on to the car.

Prodrive utilised parts built on a Laser Lines Stratasys FDM system to develop their Mini John Cooper Works WRC and the Aston Martin Racing Vantage GTE. As the Mini was developed, a total of 18 key components were identified for direct digital manufacture, with two further parts made as a result of FDM tooling. The direct digital manufactured parts included various display pods, sensor housings, dust caps and ducting. Even wheel arch extensions proved robust enough to be used on the competition car.

One example of FDM tooling used by Prodrive was a flexible airbox duct. The duct was required for the engine air intake. The fastest and most cost-effective route was clearly AM. FDM masters were produced by Prodrive in just 52 hours with six hours of finishing – compared to traditional methods which would have taken two weeks. 'There were two different versions of the brake ducts for the Aston Martin,' says Rick Simpson, former chief designer at Aston Martin Racing.

'One set were ABS, but we did some rapid tooling by wrapping carbon fibre pre-preg around soluble FDM mandrels.

'The rear inner fender linings on the Aston Martin were produced using FDM thin panel layup tools,' says Allen Kreemer of Stratasys.

For Prodrive, functional prototypes provided durability, risk reduction, fast iterations and 24/7 access.

The end-use parts offer no limitations due to machine tool availability or manufacturability, no tooling costs and no obsolescence. Small wonder then, that these rapid prototype technologies are taking motorsport by storm.

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TECHNOLOGY – CGTECH

A winning formula Freeform Technology uses CGTech's VERICUT, the world's most advanced independent CNC tool simulation and optimisation software, to provide peace of mind and a safety net for its machines

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stablished in 2008, the majority of Buckinghambased Freeform Technology’s work is connected to the motorsport industry. This might be expected as its co-directors knew each other when they both worked at Red Bull Racing. Company Director, Simon Burchett, explains: 'At least 80 per cent of our work is F1, and then there’s the non-F1 side of it that’s still motorsport. The balance is made up of subcontracts and composite companies that need additional capacity or pattern machining.

Many have their own pattern shops so we act as an overflow capacity for them.'

Having decided to form a subcontract engineering company, the directors were well aware that while the metalworking side offers huge opportunities, there were also many companies who wanted to do it, making it a ruthless industry sector with high start-up costs. Subsequently the decision was made to focus on producing patterns and moulds for the ever increasing composite components.

The Red Bull pattern shop had three Breton machining centres, 'so the first thing we did was go to the company that supplies them to work something out,' recalls Simon Burchett. 'However, the finance package was beyond us at the time so that was a nonstarter. We looked at second-hand machines, but nothing suitable was available so we approached CMS Industries. The price seemed

more reasonable and we flew out to the factory in Milan, Italy.

We were both very impressed with the company so we came back to get the finance in place, bit the bullet and re-mortgaged the house just at the start of the global recession.

'Fortunately for us Red Bull did help us out with work and free-issued material. We have found that like Red Bull, many of the F1 teams we have worked for are very mature and supportive, they really appreciate a supplier that does good work and they don’t want to lose them so they’ll do what they need to do to make sure you keep going.'

The new CMS machine came with a warranty of 3,000 hours or 12 months, whichever came first and not many businesses hit that in the first year. Freeform clocked it up within nine months due to the fact that it had to keep it constantly running. 'It was our only machine, our only source of income, we were working from 6 am until midnight and if at any point in the first year that machine went down we would have gone bust,' says Burchett.

Having used VERICUT at Red Bull both partners were keen to invest in the simulation and optimisation software. Burchett says: 'We could not afford it until the second year, and going home at night leaving the machine running wondering what you would return to in the morning was quite worrying.

'We always had VERICUT at Red Bull as it was part of the

Jake Oliveira, CAM programmer, applied VERICUT NC simulation to the company’s 5-axis DMG machining centre

process, so not to have it was stressful to say the least. As soon as we could afford it, we invested in the software because it is not just for big businesses. With only one machine you have to protect it. If it goes down then you are effectively unable to work, and when the machine breaks it cost so much to fix. After a major break-down you think ‘with that money I could have had VERICUT’.

We felt it was a false economy not to have the level of protection

offered by the software. Other small companies see it as a massive overhead; we see it as an essential tool of cost cutting and survival in the long run.'

Every one of the 13 staff at Freeform will push the start button, go home and be confident to let the NC program run until the end of the machining cycle.

'And,' adds Burchett, 'the quality of work we provide would be affected by a machine tool that had suffered a crash because the

“There is no point cutting a piece of material for three or four hours for it to be wrong, because the cost to do that is considerable” www.racecar-engineering.com • Advaanced Engineering supplement

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accuracy of the machine will be affected. So as soon as we could get VERICUT there really was no hesitation.'

After turning over a modest profit in the first year the company purchased another machine tool and started to employ highly skilled staff.

Although the company was tight on floorspace, a project for Renault F1 (Lotus F1) for brake ducting components required around 18 patterns. This made the investment crucial. The tolerances were very tight because any air leak would reduce efficiency. A new DMG machining centre was purchased to meet the project demands, and to also provide the ability to machine metallic components. Today the company operates three CMS machines as well as two DMG machining centres.

Native Siemens NX 3D CAD models are supplied by most customers. 'We’ve had VERICUT for just over three years and its performance is always robust,' says Burchett. 'It’s always been what you think it’s going to be, very accurate, and it’s not going to throw up any sort of spurious mistakes. Using the latest version of VERICUT we’ve noticed the difference in verification speed, it has been reduced considerably and we can leave it run overnight.'

Four staff at Freeform carry out programming and verifying tasks, but the company is looking to train more people because at busy times it can become a bottleneck. 'Having four people programming with two VERICUT licences is never going to be that easy,' says Burchett. 'We will need another licence but I don’t have

Every NC program has to pass through VERICUT to ensure the safety of the machine tools. VERICUT supports Freeform Technology’s production of complex moulds and composite patterns for the motorsport sector

a problem paying for it. We see it as a working overhead, it is a key investment as far as we’re concerned, having a machine that is smashed up and unable to make the parts accurately is a liability.

'There is no point cutting a piece of material for three or four hours for it to be wrong because the cost to do that is considerable. It’s not just the cost of remaking the part, it is the cost of not being able to do another job while you are waiting for that one to be finished - again. Our objective is to make sure what goes on the machine comes off right the first time. Mistakes upset the customer, ruin your machine and business, and a five

minute lapse of concentration that leads to a mistake can effect a week of work. It becomes counter-productive. Staff then have to work longer hours and get tired, the morale drops and the standard of work declines.'

For Freeform, VERICUT simulation and optimisation software is as important as its CAM package. 'We’ve got to have faith in our CAM package,' says Burchett. 'When we do a tool path it’s not going to gouge the part for some random reason as we apply complex tool paths. We have 100 per cent

confidence in NX and 100 per cent confidence in VERICUT, so it’s almost like an additional safety net for us. Our staff are also confident, which allows them to do one job, leave it and then set up there next job.'

Freeform prides itself on the fact that it has earned a good reputation for delivering quality, and has never delivered anything late. 'Even though we have stretched the day, most people would say the working day ends at five, we’d say midnight, says Burchett. 'Even if there’s just a slight change to the tool path nothing goes on the machine tools unless it has been run through VERICUT first; purely and simply because it is safe.

'As soon as we got VERICUT we could programme to run through the night, knowing we could leave the machine running for the extra hours and it would be safe. Sometimes we come in the morning and the machine is still running. If you think that if we didn’t have VERICUT then there is the chance you are going to come in, the machine has mangled the part which cost thousands and the jobs not done, your customer is not happy, you are not getting paid, the machine is broken and going to cost to repair. So for us not having VERICUT was not an option and also we can sleep at night.'

Advanced Engineering supplement • www.racecar-engineering.com

TECHNOLOGY - COMPOSITES

The fibres of being Carbon fibre may currently rule the world of composites, but in this competitive, constantly evolving and innovating industry, there’s an ever-growing list of alternatives for teams looking to get ahead…

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he importance of composites is immeasurable right now, whether it be in the automotive, motorsport or aerospace sectors. With the composite market predicted to grow at an average annual global rate of 6 per cent to €90bn by 2015 (compared to €80bn in 2012) companies are fighting hard to develop the next new composite.

The future of the carbon fibre industry is nicely set for success.

The beauty of carbon fibre is that it is five times as strong as steel, two times as stiff and yet weighs two-thirds less, which is why it plays such a dominant role in the motorsport industry and will continue to do so for the near future.

by GEMMA HATTON Put simply, carbon fibre is actually thin strands – 0.0050.010mm in diameter – of carbon that are twisted together to form a yarn, which are then woven to create a ‘cloth’. This is then used to mould parts with the aid of a stiff resin – usually epoxy. Essentially, carbon fibre is manufactured

The composite chassis of the Bloodhound SSC, an example of where composites have been pushed to the absolute limits using URT materials

www.racecar-engineering.com • Advanced Engineering supplement

by oxidising the fibre by a furnace, and then graphitising it at high temperatures. Then, by controlling the temperatures you can determine the specific performance characteristics.

Great, then, for motorsport and projects such as the Bloodhound supersonic car. Unfortunately, everything comes at a cost, and for carbon fibre it is a big one.

This is the reason why we haven’t

seen this material utilised in many production cars. However, this may change as Andy Smith, principal engineer of composites research at McLaren Automotive explains.

‘There are two fundamental problems with getting composites into road cars and they’re both to do with cost: cost of the raw fibre and the cost of the manufacture,’ he says. ‘With ever-increasing legislation for reduced fuel consumption and CO2 emissions, vehicle weight is a major issue, so carbon fibre is ideal.

‘However, there is a worldwide effort to reduce the cost of fibre, mainly by finding a lower cost precursor [the raw material that carbon fibre is made from] because the process of turning it into carbon fibre is just a heat treatment, so it’s finding a way

you can make a consistent but cheaper precursor. I’m sure this will happen in the not-too-distant future. It’s interesting that the automotive industry has talked about the magical $2 or $5 per lb fibre cost target for years, but seem to have ignored inflation during that time.’

Meanwhile, nanocomposites are materials that incorporate elements that are less than 100 nanometres in size into a matrix of standard material.

This addition of nanoparticles can be engineered to enhance the macroscopic properties such as mechanical strength, toughness and thermal conductivity of the composite.

Nanocomposites differ from conventional composites because of the high surface-to-volume ratio of the reinforcing phase and its exceptionally high aspect ratio.

The reinforcing material can be made up of particles, sheets or fibres, and are dispersed into the material throughout processing.

The high surface area means that a relatively small amount of nanoscale reinforcement can have a significant effect on the properties of the composite.

An example of a type of reinforcement are carbon nanotubes (CNTs), cylindrical carbon molecules that have extraordinary thermal conductivity and electrical properties. Composites are strengthened by adding layers over one another and then bonded by resin. CNTs can be

incorporated into the structure by ‘nanostitching’, which aligns rows of carbon nanotubes perpendicular to the layers, effectively filling the spaces between them and stitching the layers together. The use of CNTs does not add weight, as they are simply taking up the space where the former, heavier resin would have been. Composites that incorporate CNTs into their microstructure are approximately 10 times stronger, and a million times more electrically conductive then composites without.

There have been high levels of activity surrounding the nanocomposite industry.

‘Nanocomposites are an interesting development with huge potential, but not a technology we are using

application of nanotechnology.

‘The advantage of using nano fillers is that the effects are realised at much lower loadings than with conventional fillers, and they can have significant benefits to properties such as strength, stiffness, thermal and electrical conductivity,’ continued Smith. ‘A potential downside is that some nano reinforcements have been reported to have a detrimental effect on impact and toughness – it’s a trade-off.’

Fuzzy fibres are on the brink of becoming commercial and overall, Smith predicts that due to the recent developments in the nanocomposite industry, we could see nanocomposites take centre-stage in the immediate future.

Another company who is

“There is a worldwide effort to reduce the cost of fibre, mainly by finding a cheaper precursor” at present in automotive,’ says Smith. ‘For me, the most interesting application is the development of “fuzzy fibres” – nano-fibres grown on carbon fibres to provide improved electrical and thermal conductivity – essentially mimicking a metal, which opens up some interesting possibilities.’

For McLaren Automotive, polymer modification for injection moulded parts is looking to be the most likely near term

investing in this technology is Bercella Carbon Fiber.

‘We’re developing a project on nanocomposites with the University of Parma based on the idea to use piezo-material to modify the shape of a component,’ says Massimo Bercella. This can be achieved by the piezoelectric effect whereby applying a mechanical force to the material generates an electrical voltage, and when an electrical voltage is applied,

the material deforms. Therefore, piezoelectric materials can be used as sensors, actuators, or for power generation. However, original piezoelectric material is very brittle, so to overcome this, piezoelectric composites were developed. Because the fibre is so flexible, it can withstand high deformation without breaking. It is also compatible with other composite processing techniques, making it ideal to be used as an embedded sensor. ‘Imagine being able to modify the shape of a wing or an aerodynamic surface at every moment with a simple electrical signal,’ added Bercella.

‘It could be a revolution for both aerospace and automotive.’

This technology is still being born, but could potentially be a futuristic breakthrough.

IMPRACTICAL SOLUTION? However, not everyone is certain that nanocomposites are the future. ‘We have mixed feelings about nanocomposites,’ explains Christophe Buchler, global director of sales and marketing from Pyromeral Systems. ‘It is a very vague notion that can include a wide range of technologies, materials, chemistries or concepts.

Some of these concepts are fairly new, but others have been around for a very long time. Some have resulted in incremental improvements in composite materials, but many are impractical and difficult to

With the outer body panels removed, it is obvious how the carbon-fibre MonoCell integrates into the McLaren MP4-12C road car chassis May 2013 • •www.racecar-engineering.com Advanced Engineering supplement www.racecar-engineering.com 63

TECHNOLOGY - COMPOSITES implement outside a laboratory.

Some of the work done in the industry on nanocomposites can be interesting, but whether any of that will result in breakthrough advances is yet to see. Regarding Pyromeral Systems, we have been working on nano-structured inorganic polymers and matrix systems for 25 years. However, we do not see this as a defining feature of the material and do not see much technical value in emphasising it.’

Thermoplastics have seen a lot of research over the last few years, and are quickly becoming much more than merely an idea. They are a group of polymers that become homogenised liquid, and therefore mouldable at certain temperatures, and then form a solid once cooled. But this process is also reversible, so the polymer can be constantly re-heated and re-cooled – which is the main difference between a thermoplastic and a thermoset.

Thermoplastics are currently widely used as a replacement for injection moulded parts.

‘Thermoplastics for use in structural composites are definitely on our radar,’ says Smith. ‘The benefits include recyclability, improved toughness and energy absorption, good hot/wet properties, environmental resistance and potential simplification in processing.’ The latter is particularly interesting for automotive applications, says Smith, ‘Thermoplasticbased composites can be pressformed – a familiar process to OEMs – re-formed and welded.

Downsides include the high cost of materials and manufacture as most of this class of materials is made for aerospace, as well as the high processing temperatures, which are in the region of 300–400degC. Complex geometries can also be a drawback, since most of the structural thermoplastic composite materials come in the form of pre-preg or preconsolidated sheets which have no drape at room temperature, unlike thermoset pre-pregs.’

‘We are investing in a lot of compression moulding, especially with thermoplastic materials because we believe that this is the future for

Bercella Carbon Fiber, located in Varano de’ Melegari in Parma, is currently working on a project with nanocomposites, based on the idea of using piezo-material to modify the shape of a component

composites in mass production, especially road cars,’ adds Bercella. ‘You simply cannot produce thousands of parts per month with autoclave or vacuum moulding. However, it is a different story for motorsport. Since the volumes of production are small, it will be difficult to justify the high cost of tool required to produce thermoplastic parts.’

Out of autoclave composite manufacturing is an alternative to the traditional high pressure and temperature autoclave curing process, which is extremely expensive. The way that this process achieves the desired fibre content and elimination of voids is by placing the layup within a mould and applying pressure and vacuum by resin transfer moulding (RTM) or

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vacuum-assisted resin transfer moulding (VARTM).

AGAINST AUTOCLAVES ‘For automotive series production, autoclaves will never meet the rates required,’ says Smith. ‘A lot of effort has been expended by the thermoset pre-preg manufacturers in recent years to develop resin systems that cure rapidly – a couple of minutes – and can be press-moulded in isothermal tools, as well as systems that give the low void/ high fibre content characteristic of autoclave processing, but at lower pressures and temperatures, to reduce cost.

‘The current McLaren composite chassis is manufactured using a resin transfer process whereby dry fabric pre-forms are loaded

into a tool which is then placed in a press and resin injected under pressure and cured. The cycle time for us is four hours, which fits in with the maximum number of vehicles we will ever produce, of 4000 per year.

BMW will use a similar system to produce the upcoming i3, although their system is a variant on the usual RTM process, known as HP-RTM – high pressure resin transfer moulding. Here, the tool is kept slightly open when the resin is injected at high pressure – this allows the tool to fill in a matter of seconds. The tool is then closed, forcing the resin down through the laminate rather than along the fibres. For structural composite use in the automotive sector, I think RTM is the manufacturing process of choice for volumes up to – say –

Part of the Bloodhound SSC showing a cross-section of the URT Composites used

50,000 units per year.

‘Motorsport will still use conventional pre-pregs cured in autoclaves for the foreseeable future. Aerospace is also looking at out-of-autoclave processes due to the fact that the size of parts now being considered make autoclaves a very expensive option.’

This is the general feeling from many of the manufacturers that I interviewed, such as Bercella, who concluded: ‘I think out-of-autoclave is a smart process for non-structural parts

for startup companies at the beginning stages. If you want to produce high-quality structural parts like monocoques or crashboxes where you have very severe rules to withstand, you simply must use an autoclave!’

However, this hasn’t stopped the development of out-ofautoclave manufacturing. In Australia, the nine-year FR-1 project – a two-seat roadster sportscar – was the first carbon fibre monocoque cockpit chassis to be built in Australia. And it was designed and moulded

out of autoclave. This project involved VCAMM, Autohorizon, Boeing and GMS composites to design and build the cockpit chassis and the glass fibre tooling. An epoxy pre-preg GMS EP270 was used and moulded at only 70degC, but did include eight 16-hour cure phases and a final post cure. However, it weighs in at a light 80kg and still provides the required high torsional rigidity, which was achieved by the design optimisation of the number and orientation of the carbon fibre plies.

It took AUD$1m of investment to complete the handmade project, which makes it unlikely to take off in the motorsport and automotive worlds. However, it does prove that this process is a successful alternative, and interestingly, it is claimed that out of autoclave manufacturing costs are a factor of four times lower, with tooling costs typically reduced by 50 per cent. If this process can become more commercialised then it could prove an intriguing opportunity.

With the introduction of the

1.6-litre turbocharged V6 engines in the 2014 F1 season, the issue of high temperatures is fast becoming a major one.

One of the major companies for heat treatments is Zircotec, famed for their thermal coatings, and more recently they’re newly developed ThermoHold Gold coatings. These coatings are extremely efficient at heat protection – for instance Zircoflex, used in F1, can reduce surface temperatures by up to 64 per cent.

Some manufacturers produce materials that are adequate to resist heat without coatings, such as Pyromeral Systems, as Buchler explains. ‘If coping with higher temperatures is an issue, our materials are ideally suited to provide a user-friendly and practical solution to this problem,’ he said. ‘We offer solutions for parts exposed to temperatures between 350degC and 1000degC, which far exceeds the capabilities of carbon fibre reinforced composites (CFRP) with organic matrices. Due to the thermal properties of our materials, parts tend to be much more durable than those made of CFRP when exposed to heat. Other advantages include short lead times, use of inexpensive and conventional tooling materials – a rare and valuable feature in the world of high temperature composites – and the use of clean, environment-friendly chemistries and processes.’

‘Motorsport applications certainly use coatings which can range from spray-on ceramic coatings to heat reflective films, like gold,’ added Smith. ‘Our automotive applications rely on heat-shields, since packaging requirements are not as restrictive as they are for the F1 cars. Automotive, even high-end vehicles such as the MP4-12C, is heavily driven by cost, and the application of coatings can prove expensive.

‘The main area of interest for motorsport at the moment is high temperature capability.

With next year’s re-introduction of turbocharging in F1 and the aerodynamic requirements of close fitting bodywork, composite materials will really be pushed to their boundaries in terms of thermal performance.’

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TECHNOLOGY - COMPOSITES 3D PRINTING A strong current trend in the world of advanced materials is 3D printing, and as this area accumulates ever-more investment and development, the effects on the composite industry could be potentially huge.

An accomplished player in the 3D printing world is CRP Technology, who worked with CRP USA to 3D print parts for the Nissan DeltaWing Le Mans car. For motorsport applications, additive manufacturing could be yet another effective way to process composites.

‘Traditional composite materials characterised by long fibres cannot be processed with 3D printing yet,’ said a CRP spokesperson. ‘This technology requires the use of reinforced materials, but in powder form, such as Windform materials. However, using these types of materials, selective laser sintering (SLS) could be an interesting future possibility.’ This method produces prototypes by layering and overlapping polymeric material at constant temperature using a roller that rotates at opposite directions, adding a thin layer of powder on a platform where the laser ray then sinters the material, providing the necessary heat to melt the powder.

The enormous advantage of 3D printing is that there are no limits in designing, so you can design for functionality.

Parts with undercuts and complex features can be produced, which would be difficult to achieve with traditional processes. It is also considerably quicker and cheaper.

A PyroSic exhaust duct from Pyromeral Systems. The material is based on glass-ceramic matrix systems reinforced with silicon carbide or carbon, which offers great thermo-mechanical performance for motorsport applications

‘We can build individual parts and functional components in very short timescales,’ continued the CRP spokesperson.

‘Moreover Windform materials can be CNC machined, metallised and painted, adding great value to our processes for sectors that need beautifully-finished and functional parts. At this stage it is not possible to create an entire chassis of a car with 3D printing due to the limited dimensions of current printers. Furthermore, the mechanical properties of the SLS materials need to be improved for that kind of application.’ But the possibilities are certainly intriguing.

‘Among the many areas of research in the composite industry today, we believe that out-of-autoclave processing, high temperature materials and advances in tooling materials will be the most relevant for the motorsport industry,’ concluded Buchlet. ‘There are many other topics of interest in the composite industry today, such as fibre placement technologies for automated processing, lowcost carbon fibres, design and modeling, repair technologies and natural fibres. However, most of those efforts primarily target the aerospace and automotive industry.’

“We can build individual parts and functional components in very short timescales”

‘For automotive applications, I think automation is the key, particularly for structural applications,’ added Smith.

‘My personal feelings are that thermoplastic composites will become the material of choice for mainstream automotive manufacture, driven by recyclability and the similarity in processing methods with current metallic technology.

Also, I think high-end applications will continue to use continuous fibre, but general applications will use discontinuous short fibre materials, maybe with localised continuous fibre reinforcement. This will allow easier processing into complex geometries since the fibres can move relative to one another without restraint.’

The NeaR fuTuRe ‘Motorsport, due to the low volumes and high performance required, is likely to stay with current technologies,’ said Smith. ‘The main area of interest is the requirement for high temperature capability. With next year’s re-introduction of turbocharging in F1 and the aerodynamic requirements of close fitting bodywork – composite materials will really be pushed in terms of their thermal performance.’

There is no doubt that the world of composites today is an exciting one, with such high levels of development, investment and innovation, the materials and manufacturing of the motorsport, automotive and aerospace sectors could be revolutionised in the not-toodistant-future.

The SAeRTeX SOLUTION Dresden University of Technology’s Formula Student team – elbflorace eV – feel that they are benefittng greatly from the use of Saertex LeO composite technology

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Christian Holz, head of frame and body for Elbflorace TU Dresden Formula Student Team, explains the benefits of this composite.

‘We choose the Saertex LEO System because of the Formula Student regulations – we have to make our firewall and battery case fire-resistant,’ he said.

‘With this technology we can ensure very high fire-resistance and good electrical insulation because of the glass fibre layer, which is extremely important

for our battery case. Beyond that, the LEO is easy to manage and gives us the best possible combination of fire-resistance, reduced weight and high strength values.

‘We think that the LEO technology is a future material for Formula Student, and we will continue using this technology next season and hope to help Saertex to optimise it for the specific application of Formula Student cars.’

Advanced Engineering Show Hall 5, Stand D202