Carbon fiber is the thin long strand of material that is mostly composed of carbon atoms. These carbon atoms are attached in microscopic crystals which are more or less arrayed parallel into the long axis of the fiber. The crystal alignment will make the fiber strong for its size.
The process of producing carbon fibre is part chemical as well as part mechanical. The precursor is cast into long strands and heated into high temperature without letting it in contact with oxygen.
The first process is known as spinning in which acrylonitrile plastic powder is combined with another plastic such as methyl methacrylate or methyl acrylate that will be reacted with catalyst in a solution process of polymerization to produce the polyacrylonitrile plastic. Then the plastic is spun into fibers using one of the different methods. The fibers will be washed and stretched into the desired diameter of the fiber.
Before carbonizing the fibers, they will be chemically altered first to convert their linear atomic bonding into a more stable ladder bonding. This will cause the fiber to get oxygen molecules from the air and put into new order their atomic bonding pattern. If the fibers have already been stabilized, they will be heated for minutes in a furnace that is filled with mixture of gas that does not have oxygen content. This will prevent the fibers from burning in high temperatures. While they are heating, they start to lose their non-carbon atoms and the remaining carbon atoms will form carbon crystals that are tightly bonded.
After carbonizing, fibers will have a surface that doest not attach well with the other materials utilized in composite materials. These surfaces are slightly oxidized to provide fibers with better bonding properties.
After treating the surface, the fibers are then coated so it can be protected against damage during weaving or winding. This is known as the sizing process. Materials for coating are selected to be compatible with adhesive used to produce composite materials. Coated fibers are wound into bobbins that are loaded into spinning machine, twisting the fibers into yarns of several sizes.