What are the key steps in the manufacturing process of carbon fiber fabric?

The manufacturing process of carbon fiber fabric involves multiple key steps, from the preparation of raw materials to the final product inspection. The main steps are as follows:

Raw Material Preparation

Selection of Carbon Fiber: High-quality carbon fibers are the core raw material. They are usually made from precursor materials such as polyacrylonitrile (PAN), pitch, or rayon through processes like spinning, stabilization, and carbonization. The selection of carbon fiber depends on specific performance requirements, such as strength, modulus, and heat resistance.

Choice of Resin Matrix: The resin matrix plays a crucial role in binding carbon fibers and transferring loads. Common resins include epoxy resins, polyester resins, and phenolic resins. The choice of resin depends on factors like the intended application, curing conditions, and required chemical resistance.

Weaving or Non-Woven Fabric Formation

Weaving: In the weaving process, carbon fibers are interlaced at right angles to form a fabric structure. There are various weaving patterns, such as plain weave, twill weave, and satin weave. Plain weave offers good dimensional stability and surface smoothness; twill weave has better flexibility and drapability; satin weave provides a smoother surface and higher strength in specific directions.

Non-Woven Fabric Production: For non-woven carbon fiber fabrics, carbon fibers are randomly distributed and bonded together using techniques like needle punching or chemical bonding. Non-woven fabrics have advantages such as high production efficiency and good formability, and are suitable for applications requiring complex shapes.

Resin Impregnation

Pre-Impregnation: Carbon fiber fabrics are impregnated with resin in advance to form prepregs. This can be done through methods like dip coating or roll coating, where the fabric is immersed in a resin bath or passed through a resin-coated roller to ensure uniform resin impregnation.

In-Situ Impregnation: In some cases, resin impregnation is carried out during the molding process. For example, in resin transfer molding (RTM) or vacuum-assisted resin transfer molding (VARTM), the dry carbon fiber fabric is placed in a mold, and then the resin is injected into the mold to impregnate the fabric.

Molding and Curing

Molding: The impregnated carbon fiber fabric is placed in a mold with a specific shape and size. The mold can be made of metal, composite materials, or silicone rubber, depending on the production scale and requirements. The fabric is then shaped according to the mold using techniques like compression molding, vacuum bag molding, or autoclave molding.

Curing: Curing is a key step to solidify the resin matrix. It involves heating the molded part to a specific temperature and holding it for a certain period to allow the resin to undergo a chemical reaction and harden. The curing process can be accelerated by adding curing agents or using ultraviolet light in some cases.

Post-Processing

Trimming: After curing, the molded part is removed from the mold and excess material around the edges is trimmed to achieve the final shape and size. This can be done using cutting tools like scissors, knives, or laser cutters.

Surface Treatment: Surface treatment is often required to improve the appearance and performance of the carbon fiber fabric product. This may include sanding to smooth the surface, polishing to enhance gloss, and coating with protective layers to improve scratch resistance and chemical resistance.

Inspection and Quality Control: The final carbon fiber fabric products are inspected for quality. This involves checking for defects such as voids, delamination, and fiber misalignment. Nondestructive testing methods like ultrasonic testing and X-ray inspection may be used to detect internal defects.