Carbon Fiber in General
The atomic structure of carbon explains some of the extraordinary properties of a carbon composite. In a graphite structure, sheets of hexagonal rings are connected into virtually endless molecules. The bonds between carbon atoms within the sheets are very strong but interactions between the sheets are weaker. Sheets can easily slide past each other, which we actually take advantage of when using a pencil.
In a carbon fiber, on the other hand, the hexagonal rings are arranged in ribbons rather than sheets. The ribbons are parallel to the axis of the fiber and interlinked and locked to each other in a complex way which is believed to give the carbon fiber its unique characteristics. Each carbon fiber is thin, only about a fifth of a human hair.
The carbon fibers are bundled together and woven into a fabric and by adding a resin . Pre-preg is a type of fabric which is pre-impregnated by the manufacturer. CarboComp usually works with a material called Pre-Preg. This is a type of fiber cloth in which the resin has been pre-impregnated by the manufacturer (hence pre-preg). The resin can be either polyester, epoxy, or a number of other types of glue, epoxy being the most commonly used.
Manufacturers of pre-preg are able to precisely control the amount and type of resin based on the customer's specifications and the application. With pre-preg consistent ratios of fiber to resin can be ensured and, hence, maximum strength and quality of the final product.
The result is simply lighter and stronger products.
The CarboComp proccess
Pre-preg is relatively easy and precise to work with. Each layer is cut to millimeter precision with a cutter and applied directly to the mould. Aluminium moulds are commonly used because of the superior finish they give and their long life. The mould is then sealed very carefully in a vacuum bag and placed into an Autoclave for curing.
The most common pre-preg fiber that CarboComp uses cures at 120°C (248°F) in 11/2 hours. To increase finish quality and performance the curing process operates under both pressure (4 bar) and vacuum (at least 90 kPa).
Since weight and stiffness are the critical properties of carbon fiber, pre-preg offers greater consistency and control of the final product. CarboComp works with many variations in weight and structure of pre-preg cabon fiber.