During the conventional carbon fiber conversion process, crimped or spooled PAN fiber feeds into the pretreatment module and proceeds through a steam heating and stretching process.
From there, it enters the oxidation step. The material darkens in color from white to black as it weaves through multiple ovens.
Simultaneously, oxygen is diffused into the fibers which undergo cross-linking to raise the melting temperature.
It typically takes 80 to 120 minutes for the material to pass through the ovens, with oxidation occurring when the air temperature rises to 200 - 300 degrees Celsius.
Next, the material makes a single pass through two carbonization furnaces. The first typically operates at 500 - 1000 degrees Celsius, the second at 1000 - 1500 degrees Celsius.
Approximately half of the material is vaporized during carbonization, with gasses exhausted through an incineration system.
The remaining material is nearly 100 percent pure carbon as it enters a surface treatment process that renders it chemically compatible with resin.
A thin coat of polymer is applied to the carbon during sizing, which protects the fiber and makes it easier to handle.
The carbon fiber is then dried and packaged -- typically by spooling.