A Glimpse Inside the Carbon Fiber Fabrication Process
The carbon fiber fabrication process involves many steps. The process begins with a precursor, the raw material used to make the carbon fiber. Once the precursor fibers are carbonized, oxidized, and sized they can be woven into fabrics, braids, or used directly in the two forms (untwisted continuous thread). The fibers are mixed with resins and formed into composite materials using heat and pressure. Producing everything from laminates, to sheets, to tubes, and connectors.
Carbon Fabrication Step 1: Making Carbon Fiber
The process usually consists of five steps:
Spinning: Carbon Fiber Fabrication always begins with a precursor. Carbon Fiber precursors are organic polymers, usually polyacrylonitrile (PAN). Gasses, liquids, or other materials are added to achieve varied properties. The fibers are spun, washed, and stretched into long strands.
Stabilizing: Chemicals are added to stabilize the fibers.
Carbonizing: The long strands then undergo high heat in anaerobic conditions to expel all non-carbon material. This step creates tightly woven chains of almost pure carbon.
Surface treatment: The carbonized strands are then oxidized to improve bonding.
Sizing: The resulting fibers are coated with materials to protect the fibers while they are spun and/or woven. This coating material is chosen to bond best with the adhesives that will be used in the final products. The coated strands (tow) are wound onto bobbins in order to be further processed.
Carbon Fabrication Step 2: Creating Base Products
Once the fibers are created and wound they can be woven into fabrics. A variety of carbon fiber weaves are available to suit almost any purpose.
These weaves can then be processed further to form CFRPs (carbon fiber reinforced polymers or carbon fiber reinforced plastics). CFRPs are composite materials generally made up of two parts: a matrix and a reinforcement. The reinforcement is always the carbon fiber itself, which provides strength and rigidity to the composite. The matrix is a polymer resin, usually epoxy, that binds the fibers together. CFRPs can be used in single sheets or shaped in various ways. Examples include sheets, tubes, rods, angles, and I-beams. They can also be combined with several other CFRP layers, or layers of other materials, including a broad range of core materials (i.e. foam).
Carbon Fabrication Step 3: Designing the Final Product
Carbon fiber fabricators have created a variety of carbon fiber composite materials. These materials can either be sold to other manufacturers, for use in their products or used for product creation in-house. Almost any item imaginable can be made from these carbon fiber base materials. All it takes is a vivid imagination and engineering and design skills. The unique properties of carbon fiber must be taken into account during the carbon fiber fabrication process. A variety of manufacturing techniques can be used to create the final product depending on which base products are being used and the desired results. Some of these processes include:
Molding
Vacuum bagging
Compression molding
Filament winding
There are several processes involved in carbon fabrication. Transforming raw PAN (polyacrylonitrile, the precursor) into a finished product involves multiple steps. It is imperative that each of these steps is done with strict quality control measures. This ensures the final product is strong, stiff, beautiful, and without structural flaws. Anyone who has worked with carbon fiber products will agree that the results of this lengthy and complicated fabrication process are well worth it.
