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.
Commented Richard Brady, module leader in the digital manufacturing
department at Williams F1, "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, two-thirds from
laser-sintered plastic powder, a proportion that 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 27th
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.
Continued Mr Brady, "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
£1,000 for each iteration of the design. Tooling costing £25,000 to produce a
carbon fibre lay-up is the traditional production route, involving 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 on this season, the FW28 hydraulics
needed to be redesigned and tested in a week, in time for the next Grand Prix,
and 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 suite of four
clamps for each of the eight cars, plus spares, were built overnight in a
single, fully automatic, four-hour build in one of the EOSINT P 385s, 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 concluded, "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
useable in a host of demanding applications."