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Laser sintering used to manufacture production F1 parts

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WilliamsF1 is using EOSINT P 385 machines for the rapid manufacture of components for use in full-size car mock-ups as well as for the team's test and race cars.

During 2005, EOS laser sintering equipment was installed at the WilliamsF1 headquarters in Grove, Oxfordshire, primarily for making prototypes quickly from plastic powders to test in a wind tunnel. However, the technology is finding important new applications in the rapid manufacture (RM) of parts for full-size car mock-ups as well as for the team's test and race cars.

Williams has used stereolithography (SLA) for rapid prototyping (RP) since 1987, but was aware of the drawbacks - namely long build times, brittleness of the components produced, long manual finishing times and the expense of the resin. The company wanted to diversify into using more robust materials and alternative processes to increase the applications for which RP/RM components could be used and to reduce production times. They were mindful that, as speed is of the essence in all aspects of Formula 1 racing, the advantages would be considerable.

Richard Brady, module leader in the digital manufacturing department at Williams F1, comments: "Before we started laser sintering components, we frequently had to remake SLA components in our mock-ups, as repeated handling often caused them to break.

"In contrast, we have not had a single mechanical failure of any component we have made by laser-sintering. They are much tougher and more durable, and are rapidly replacing parts made by other techniques."

For wind tunnel applications, an increasing number of components like the brake blocks, mirror and other exterior items are now produced by plastic laser-sintering. However, the main benefit of the technology has been in the construction of car mock-ups, which, until a few years ago, were typically built in equal thirds from SLA, aluminium and traditional pattern-making materials.

Today, virtually the whole mock-up is made of RP materials, with two-thirds from laser-sintered plastic powder, and that proportion is increasing. Materials used are glass-filled nylon, polystyrene, and Alumide – a mixture of polyamide and aluminium powders that, when sintered, has a metallic appearance and may be readily milled and drilled.

On the mock-up for the current FW28 car, launched by WilliamsF1 on 27 January 2006, most of the engine parts and the entire gearbox, apart from the main casing, were produced on the EOSINT P 385 machines. So too was the rear impact structure, including the suspension, as well as the brakes, front and rear uprights, exhausts and heat shields.

Mr Brady continues: "Parts of the body and internals like electrical wiring looms can receive heavy handling by engineers, but the laser-sintered parts stand up well. There has also been a big improvement in the quality and appearance of the mock-up, with the laser-sintered parts fitting together perfectly nearly every time, saving time previously wasted modifying components to fit. The same is true of parts made for our race and test cars, which are freely interchangeable across all seven or eight FW28s."

All WilliamsF1 cars being raced this season contain around 20 non-stressed items manufactured by laser-sintering, particularly those components that would be difficult and time-consuming to make by other methods. Typical examples are electrical enclosures, cooling ducts and the antenna housing, which was previously of hand-laid Kevlar.

There is another component, which WilliamsF1 was not prepared to identify, that is laser-sintered in two days for the test cars and costs less than £1000 for each iteration of the design. The traditional production route requires tooling that costs £25,000 to produce a carbon fibre lay-up - all of which entails a lead-time of several weeks. It is true that the RM parts cannot be used on the racecars for this particular application, as their thermal characteristics are inadequate, so tooling is still needed eventually. However, development time is considerably shortened by laser-sintering in the early design stages, and the expense of modifying or even remaking the tooling is avoided.

A simple example of RM that Mr Brady was happy to speak about in detail are the clamps that bolt to the chassis under the driver's legs to retain hydraulic hoses and an electrical loom. Early in this season, the FW28 hydraulics needed to be redesigned and tested in a week, in time for the next Grand Prix; as part of that process, the clamps had to be modified and remade.

The job was far from simple, as four different types of clamp had to be made for each car. Scallops of different sizes were included to fit around hoses and wires of various diameters, and the underside of the clamps had to be sculpted in 3D to match the contour of the cockpit floor. The set of four clamps for each of the eight cars, plus spares, was built overnight in a single, fully automatic, four-hour build in one of the EOSINT P 385 machines, ready for the following morning.

Previously they would have been milled from solid aluminium, involving two hours of programming from the CAD model plus post-processing. Following that, a half-hour cycle would have been required on a machining centre to produce each clamp in two operations, and an operator would have been in attendance throughout for manually handling the parts.

Mr Brady concludes: "We are making steady progress with adopting laser-sintering into our production environment and are reaping the benefits of reduced costs and shorter lead-times from CAD screen to reality. There is a tendency to think of this and other 'rapid' technologies as RP rather than RM disciplines, but here the accent is definitely on using them for manufacturing, particularly laser-sintering.

"I predict that it will make further inroads into conventional production techniques. The only limit is one's imagination; if you can model it in CAD, you can make it, and the resulting laser-sintered parts are very robust and usable in a host of demanding applications."

21 November 2006

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