Carbon fiber products are articles made of carbon fiber materials or carbon fiber composite materials, which need to be processed by molding processes. With the development of carbon fiber technology, the molding processes of carbon fiber products are also constantly improving. The commonly used molding processes of carbon fiber products mainly include:
1. Spray molding
belongs to the low-pressure molding of hand-paste process. Chopped fibers and resin are mixed by a spray gun, and compressed air is sprayed on the mold. This is a semi-mechanized molding process, which has improved the working efficiency to a certain extent, but it still can't meet the needs of mass production.
2. Winding molding
The process of winding the continuous fiber or cloth tape impregnated with resin glue on the mandrel according to a certain rule, and then curing and demoulding to become a composite product. Carbon fiber winding can give full play to its characteristics of high specific strength, high specific modulus and low density, and the product has a single structure, which can be used to manufacture cylinders, spheres and some positive curvature rotary bodies or cylindrical carbon fiber products.
3. Liquid molding
The process of synthesizing liquid monomer into high molecular polymer, and then changing the curing reaction of polymer into composite material into one step directly in the mold, not only reduces the energy consumption in the process, but also shortens the molding cycle. However, the application of this process must be based on accurate pipeline transportation and metering and automatic control of temperature and pressure, so it is not widely used. Liquid molding mainly includes resin transfer molding, resin film infiltration molding and vacuum-assisted molding.
4. Press molding
Put the carbon fiber prepreg between the upper and lower molds, close the mold and put the mold on the hydraulic forming table. After curing the resin at high temperature and high pressure for a certain period of time, remove the carbon fiber product. This molding technology has the advantages of high efficiency, good quality of parts, high dimensional accuracy and little environmental influence, and is suitable for the molding of composite parts with batch and high strength.
5. Injection molding
This is a new technology, with short process flow, and better fiber length, achieving the purpose of energy-saving and efficient production, which is mainly applicable to the field of automobile lightweight.
6. Hand-paste molding-wet layup molding
Apply release agent and gel coat on the working surface of the mold, lay the cut carbon fiber prepreg on the working surface of the mold, brush or spray the resin system glue solution, and after reaching the required thickness, mold curing and demoulding.
7. vacuum autoclave molding
put the composite blank made of single-layer prepreg in a predetermined direction in an autoclave, and complete the curing process at a certain temperature and pressure.
8. Vacuum induction molding
Lay a "dry" carbon fiber composite material on the mold, then lay a vacuum bag, and draw out the vacuum in the system to form a negative pressure in the mold cavity, and use the pressure generated by the vacuum to press unsaturated resin into the fiber layer through the pre-laid pipeline, so that the resin can infiltrate the reinforcing material, and finally fill the whole mold. After the product is cured, remove the vacuum bag material and get the required product from the mold.
9. Lamination molding
The prepregs stacked layer by layer are placed between the upper and lower flat dies for pressure, heating and curing. This process can directly inherit the production method and equipment of wood plywood, and improve and perfect it according to the rheological properties of resin, which is suitable for making carbon fiber boards.
1. pultrusion molding
The continuous carbon fiber tow, belt or cloth impregnated with resin glue is molded and solidified by an extrusion die under the action of traction, and the profile with unlimited length is continuously produced. Pultrusion is a special process in composite molding process, and its advantage is that the production process can be fully controlled automatically and the production efficiency is high.
second, what is the difference between wet forming and dry forming of carbon fiber
There are many methods for processing and forming carbon fiber products, which can be roughly divided into wet forming and dry forming, and the products produced by the two processes have obvious differences in performance:
1. Wet process is prone to deformation during processing, and the cut-off parts are prone to desquamation, and the bonding between resin and fiber is poor, and it is prone to oxidation discoloration due to contact with air. The dry prepreg process will not appear the above situation, but it is easy to deteriorate under ultraviolet radiation.
2. The carbon fiber products made by dry process have good hardness and are easy to be processed by CNC, but the production cycle is long and it is difficult to mass produce, and the production cost is high; The cost of wet-formed products is low, the production process is relatively simple, and the production efficiency of the process is high.
in the production of carbon fiber, dry forming is mainly used in the case of high precision and high quality requirements, and wet forming is mainly used in appearance parts and mass production.