FEATURE
Issue: 

Built for speed

In a sport where fractions of a second count, motor racing teams are turning to additive manufacturing to make their cars faster. Beth Harlen investigates

Motorsport is one area that has embraced laser additive manufacturing (AM) and, given that the advantages of AM are based around innovative design and reducing the weight of components, the marriage between the production process and the sport is not really surprising.

‘Motorsport, especially F1, has pushed conventional manufacturing processes to the limit,’ said Stuart Jackson, regional manager, UK and Ireland for AM system provider EOS. ‘With AM they are able to push further, as it requires a new mindset. The ultimate aims of light weight, complex packaging, and compact sizes are all normal features when AM is applied correctly and these fit the ethos of motorsport.’

Additive manufacturing builds a component layer by layer by bonding powders, often with a laser, as opposed to the traditional method of forming the part from a solid block of material. Parts with intricate designs, such as lattice structures, can be built with AM, and the technique has short lead times, ideal for prototyping.

Laser sintering is an AM technique that fuses powdered material with a laser according to a 3D CAD model. According to Kieron Salter, managing director of digital fabrication specialists, KW Special Projects (KWSP), the primary benefit of using a laser is that it enables manufacturers to process metals such as titanium and steel. 

‘All other methods of additive manufacturing solely use plastics, and while some of those plastics do have a use on race cars in certain areas, the benefits of using metals is that you can begin to produce parts like exhaust manifolds,’ he said. ‘Those parts can effectively, for lack of a better word, be printed directly from CAD data, removing the need for tooling. So, if the design subsequently needs to be updated, the only element being changed is the software. The new printed parts then incorporate those small design changes that have been made between the last development and the current development.’

Jackson commented that education and confidence in AM is the primary challenge for adoption of the technology. He said: ‘Now that there is much more information available about the mechanical performance of AM parts, the industry is ready to increase its use.’

In an effort to aid understanding, EOS has sponsored Formula Students at several universities (see box) and expects to witness their impact on the use of AM as they move into the motorsport industry. In terms of uptake, 25 per cent of all EOS AM machines in the UK are producing parts for the motorsport industry. There are also AM companies based in France, Germany and Italy that supply the UK motorsport industry.

Recently, EOS announced that it has entered into a three-year technical partnership with Williams Grand Prix Engineering and Williams Advanced Engineering, with the aim of providing Williams with direct and high-level insights into the latest AM technologies offered by EOS to complement their existing manufacturing processes.

As part of the current agreement, Williams has just installed an EOSINT P 760, a modular plastic AM system with a build volume of 700 x 380 x 580mm, which offers expanded productivity and increased part sizes when manufacturing polymer components. Williams already owns two polymer EOS systems, and uses Alumide and Carbonmide from EOS as its standard production materials. Alumide is predominantly used to create stable parts for functional testing, while Williams uses Carbonmide for production parts on Formula One cars, in conjunction with carbon composite laminates where improved strength is required.

Designed from the ground up

KWSP’s Salter agrees that laser AM is widely exploited in motorsport but that, in order to unleash its full potential, designers need to understand how the part can be better designed from the ground up through AM. ‘One of the key problems with AM in general is that, if you simply take a part that’s been designed and manufactured using conventional processes, you can’t necessarily convert that to AM as a process,’ he said. ‘Because if you do, you’re not then exploiting the true benefits of it being additive manufacturing.’

He explained that if a part has been designed to be made using a casting or machined process, then that’s probably the best way to make it. But, by understanding the benefits of designing the part using an additive method in the first place, then additional features – like a lighter weight structure – can be designed in, which often couldn’t be done otherwise. 

KWSP uses selective laser sintering for plastics, but produces low volume, complex parts for racing cars using metal laser sintering. During a project for Strakka Racing, a British sports car team, the company – along with sister company KW Motorsport – discovered that it could reduce the lead time on the manufacture of parts significantly through the use of metal laser sintering. ‘We were able to design parts that were far more complex, and it allowed us to manufacture parts that simply couldn’t be produced using traditional machine processes,’ Salter explained. ‘Additionally, we were able to use materials that wouldn’t have been so readily available, such as titanium. On top of all those benefits – and this is unique to motor sport applications – it was also cheaper compared to traditional manufacturing methods. It was a win-win scenario.’ 

While conventional machining processes of traditional steels were considered, the team found that the results were quicker, cheaper, lighter, and stiffer through the use of laser AM and titanium metal. Salter believes this was due in part to the fact that low volumes of high value parts were being produced and that, in mainstream industries, such as automotive, the benefits of laser AM wouldn’t be as pronounced. ‘Metal laser sintering isn’t ready for mainstream industries as it’s quite a slow process,’ he explained, ‘but it does allow you to make parts you couldn’t have considered manufacturing before. As a result, you do end up with much more complex components.’ 

Freedom to explore

With a background in mechanical engineering, Salter is keen to emphasise the opportunity laser additive manufacturing provides. ‘In motorsport, engineers are given a lot of freedom to explore what the best method is for achieving a higher performance component, whereas in traditional automotive you have to design parts that are the most cost effective and are able to be mass produced,’ he commented. ‘There’s probably a wider appreciation for the parts being slightly more expensive if they’re higher performance, so in motor racing we’re trying to make things lighter, stiffer and more aerodynamic, and laser AM allows us to do that.

‘The applications go from scale model wind tunnel parts through to parts that go on the final car, and with most Formula One or Le Mans teams you’re probably talking about a production run of four to six parts. The very low volume is quite appropriate for AM, because you then avoid the need to make expensive tooling for a small volume of parts. Motorsport, medical and some areas of aerospace are unique areas where additive manufacturing can have a real benefit,’ he added, noting that compared to the other sectors motorsport has the added benefit of not having to navigate as many regulatory standards. This enables designers to progress the technology far quicker than industries like aerospace and at much lower risk.

Furthermore, he added, while it takes quite a long time to manufacture a single part using laser AM, what is removed from the process in terms of design and tooling manufacture makes the total time from design to parts installed on a race car far shorter. By streamlining that process, designers can increase their rate of development, and in turn make their cars faster than competitors.

In conclusion, Salter clarified the misconception that AM allows engineers to make whatever they want, wherever they want – which really isn’t the case. ‘You still need to have an engineering design to work from, the raw material to process, and the correct quality control in place,’ he said. ‘Ultimately it all comes down to the design level, as you need to design your part to be additively manufactured in order to realise all the raw benefits from that process.’ 

Student motor racing team wins with additive suspension

When independent club Rennteam Uni Stuttgart was due to take part in the Formula Student racing series – a competition for young engineers across Europe – they faced the challenge of how to optimise a critical part within the team’s car. The student engineers were supported by EOS and deployed an AM process in order to build the knuckle or axle-pivot – the part that connects the wheel axle with the wishbones and the track rod via a bearing. The breaking system is also attached. As the part takes all the force and momentum absorbed by the vehicle, its stability is paramount for ensuring the safety of the car. Likewise, every gram increases lap times and the less mass, the better the suspension. Finding the balance between stiffness and mass was not an easy task. ‘The wheel mount we’d been using over the last few years had already achieved a good balance between weight and rigidity, but we were sure we could improve on it,’ explained Yannick Löw from the Rennteam Uni Stuttgart. ‘We produced the part using the classic precision casting process. This, of course, led to limitations in freedom of form, which meant that the part’s potential could never be fully realised. Even back then we’d decided that for the 2012 season we’d investigate innovative ways of manufacturing the steering stub axle.’ The team of engineers began by using CAD software from Autodesk Within to match the part perfectly to the structural requirements, through the optimisation of latticed micro-structures of variable densities. ‘By the simplified, so called, 3D-Print process, our machine honed powdered metal granules, with the help of a laser, layer by layer, into the required part,’ explained Nikolai Zaepernick, business development manager, Automotive at EOS. By using AM, the development and manufacturing times were significantly reduced and the process, from design through to fabrication, was more precise. As a result, the weight of the part was reduced by 660g, leading to faster lap times and reduced fuel consumption – and a victory at the Hockenheimring that crowned the Stuttgart race team as Formula Student Germany Champions 2012.

 

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