Pre-Preg Carbon Fibre
The best way to consistently achieve professional results.
As explained earlier, pre-preg carbon fibre is simply dry carbon fibre fabric which has been impregnated with a mixed resin. The resin properties vary as do the different types of fabric and tape available but essentially the resin becomes active and starts to cure above a certain temperature.
Pre-preg carbon is simply dry fabric that has been impregnated with a temperature sensitive resin.
At lower temperatures the pre-preg carbon behaves like cardboard and can be stiff. At warmer temperatures, commonly around 20 C, the resin begins to become active and the fabric is pliable and tacky. At elevated temperatures, usually over 120 C, the resin is fully active and will cure. Temperature ranges and cure cycles obviously depend on the specific resin used.
It is far easier to control the resin to fibre ratio with Pre-preg material.
Pre-preg can be used on moulds in the same way as dry fabric but the tackiness of the warmed pre-preg makes it easy to apply to a mould and hold position. The process for pre-preg is the same as for dry fabric, except with the resin already absorbed by the fabric there is no need to add it at the fabrication stage.
Pre-preg material is far easier to lay into a mould than standard wet or dry fabric.
Pre-preg can be used with any type of mould design but the fabric still needs to be compressed to ensure maximum strength. The required pressure depends on the type of pre-preg fabric and resin used and can be more than one atmosphere (around 15psi), the pressure of a full vacuum. Therefore, some pre-pregs require additional moulding techniques, such as inflation bladders and compression moulds. Some pre pregs can also be cured in an autoclave, essentially a pressurised oven.
Prep-preg replaces the dry fabric used in the other techniques described on this website it is not a technique in of itself. However, because there is no need to add resin to pre-preg fabric it is possible to use it in more advanced technique, some of which are described briefly here.
Without having to add resin to a part during the fabrication pre-preg fabric opens up a wider range of fabrication methods, e.g. inflation bladders.