The first monocoque of Renault's next F1 car will soon be ready. Patterns have been completed, and the next stage is to produce the moulds, a high-precision job.
Cutting the carbon. By the time the process reaches the stage of taking moulds, the team possesses a chassis pattern accurate to 0.05mm. This is produced from epoxy resin after several stages of machining on computer-controlled Jobs machines.
"These parts are then spray painted with a black finish, and polished to a high-gloss finish," explains Composites Manager Colin Watts. "The following stage is much more complicated as we need to decide how the moulds will be produced: some large components, or those with very complex surfaces, for example, require more than one section mould."
A monocoque, for example, requires six different sections to produce the two moulds: four for the upper and two for the lower.
Shaping the carbon.
Once the pattern has been finished, painted and covered with a mould release agent, the Renault F1 Team's engineers cover each surface with sheets of paper cut to produce templates. These will then serve as patterns for the composites department in order that identical sheets of carbon can be cut.
To the unitiated, the raw carbon fibre might look to have the same sort of consistency as liquorice, but the reality is quite different. "The material we use is a type of carbon fibre that is produced in big sheets," continues Colin. "They are stored frozen, at a temperature of -18°C. The material includes a lot of resin to ensure that the surfaces of the moulds are completely smooth." These cut pieces of carbon are then placed carefully on the resin pattern.
Time for the autoclave.
Once the sheets of carbon have been put in place, the whole is then put into a plastic bag, from which the air is subsequently extracted. This assembly is then taken to the 'autoclave' oven, where it is 'cured' under high pressure, of around 100psi.
Nuts and bolts are inserted into each side of the mould, in order to ensure they can be adjusted to perfection during the subsequent stages of the process. "After they have cooled, the moulds are then carefully removed from the patterns. The resin pattern now has no function, and is destroyed. As for the moulds, they are machined to sand off the sharp exterior edges. They are subsequently used throughout the season to produce new chassis," concludes Colin.
To improve reactiveness, Enstone produces two sets of moulds for each monocoque, allowing the team to produce multiple chassis in parallel.