Pre-preg

Pre-preg is a term for "pre-impregnated" composite fibres where a material, such as epoxy is already present. These usually take the form of a weave or are uni-directional. They already contain an amount of the matrix material used to bond them together and to other components during manufacture. The pre-preg are mostly stored in cooled areas since activation is most commonly done by heat. Hence, composite structures built of pre-pregs will mostly require an oven or autoclave to cure out.

There are several advantages and disadvantages of the pre-preg process in comparison to the hot injection process. Pre-preg allows one to impregnate the fibers on a flat workable surface, or rather in an industrial process, and then later form the impregnated fibers to a shape which could prove to be problematic for the hot injection process. Prepreg also allows one to impregnate a bulk amount of fiber and then store it in a cooled area for an extended period of time to cure later. Unfortunately the process can also be time consuming in comparison to the hot injection process.

Material advances

Recent advances in Out-of-Autoclave (OOA) processes hold promise for improving performance and lowering costs for composite structures. Using vacuum-bag-only (VBO) for atmospheric pressures, the new OOA processes promise to deliver the less than 1 percent void content required for aerospace primary structures. Led by material scientists at Air Force Research Lab, the technique would save the costs of constructing and installing large structure autoclaves ($100M saved at NASA) and making small production runs of 100 aircraft economically viable.

See also

• Composite material
• Carbon fiber reinforced polymer