Prepregs and the manufacturing process

There is a sequence of production steps that leads from the rolls of prepregs to finished aircraft parts.

Prepregs (reinforcing materials pre-impregnated with resin and ready to use to produce composite parts) are left to warm up to room temperature overnight and are then cut to the various forms needed for the lay-up, which are stacked to a material kit for the part. Building finished parts in prepregs involves a lot of work done by hand.

Working with carefully prepared material kits brings the lay-up time for even the most complex parts down to less than two days. At room temperature, carbon and glass fibre prepregs have a much longer shelf life than is needed for the lay-up of the sheets into the moulds before they are cured under a heated press or in the autoclave oven. A new aircraft can be assembled every 2 to 3 days.

The latest prepregs require only an oven cure at 135-180°C (275-356°F) under vacuum, the material is available with woven carbon, unidirection (UD) carbon tape, woven glass and metallic mesh reinforcements. Most prepregs have had to be autocalve cured in the past.

Tooling prepregs

Top of the range of prepregs are tooling prepregs developed to build high performance composite tooling equipment.

Probably the most important feature of tooling prepregs is to achieve a smooth mould surface after curing, in order to produce perfect final parts using the final mould. Manufactured moulds not only feature an excellent surface quality but are also characterized by outstanding manufacturing life-cycles.