The carbon fiber production process is relatively energy intensive. Since a production lot is processed quasi-continuously, the production time of each production lot can be several weeks.
- The starting point is a high quality polyacrylonitrile (PAN) precursor fiber, which is specifically engineered for carbon fiber production
- The PAN precursor is then stretched and tensioned to optimize molecular and structural orientation
- On-line quality control of the PAN precursor ensures process continuity and efficiency
- The precursor is exposed to hot air, turning it into oxidized polyacrylonitrile fiber
- It is carbonized into carbon fiber by exposing it to progressively higher temperatures in a nitrogen-filled oven. The carbon fiber undergoes final carbonization at more than 1,000–1,500°C to establish strength and stiffness, and to ensure its other material properties
- At 2,000–3,000 °C, graphitization for high modulus types occurs
- The carbon fiber is surface-treated or etched to create a surface that will bond effectively
- A polymer coating (sizing) is applied to promote fiber-handling characteristics, wet-out and bonding
- Continuous fiber is wound onto bobbins
- The fiber can also be chopped or milled