From prepreg to final parts, carbon fiber composites need to be processed by the molding process. With the development of carbon fiber technology, the molding process of carbon fiber composites is also in constant progress. However, various molding processes of carbon fiber composites do not exist in the way of renewal and elimination. Many processes coexist to achieve the best effect under different conditions and situations. The following is a list of the 12 most commonly used carbon fiber composite molding processes. Let’s see everything you need to know about the 12 carbon fiber composite molding.
Spray Forming Process
It belongs to a kind of hand lay-up process of low-pressure molding. After the chopped fiber and resin are mixed by a spray gun, compressed air is sprayed on the mold. After reaching the predetermined thickness, it is pressed by hand with a rubber roller and then solidified. In order to improve the hand lay-up forming, a semi-mechanized forming process has been created, which can improve the work efficiency to a certain extent, but still can not meet the mass production, and can be used to manufacture the transition layer of automobile body, hull, bathtub, and storage tank.
Filament Winding
The process of winding the continuous fiber or cloth tape impregnated with resin glue to the mandrel according to certain rules, then curing and demoulding to form composite products. Carbon fiber winding can give full play to its characteristics of high specific strength, high specific modulus and low density. The structure of the products is single, which can be used to manufacture cylinder, sphere and some positive curvature rotary or cylindrical carbon fiber products.
Liquid Forming
In order to reduce the energy consumption and shorten the molding cycle (it only takes about 2 minutes to complete a product), the process of synthesizing liquid monomer into polymer, and then changing from polymer curing reaction to composite material, which is directly completed in the mold at the same time. However, the application of this technology must be based on accurate pipeline transportation and measurement as well as automatic control of temperature and pressure. It belongs to the cross category of polymer materials and modern high-tech science and technology, and its current application is not very wide.
Liquid forming mainly includes RTM forming process, RFI forming and vari forming.
The main advantages of resin membrane infiltration (RFI) process are that the mold is simpler than RTM process, the resin flows along the thickness direction, it is easier to infiltrate the fiber, there is no prepreg, and the cost is lower. However, the dimensional accuracy and surface quality of the products are not as good as RTM process, the void content is higher, and the efficiency is slightly lower, which is suitable for the production of large plane or simple curved surface parts.
The advantages of vacuum assisted forming (vari) are high utilization rate of raw materials, less amount of finishing, no need of prepreg and low cost. It is suitable for the production of large wall panel structural parts with normal temperature or low temperature. But the disadvantages are similar to RFI process.
Resin Transfer Molding (RTM)
Resin transfer molding (RTM) is a low-cost manufacturing method of composite materials, which was initially mainly used for aircraft secondary load-bearing structural parts, such as hatch and inspection cover. In 1996, the U.S. Defense Research Institute launched the research on low-cost RTM manufacturing technology of high-strength main load-bearing components. RTM technology has the advantages of high efficiency, low cost, good product quality, high dimensional accuracy and little environmental impact. It can be applied to the molding of composite parts with large volume, complex structure and high strength. It has become one of the most active research directions in the field of aerospace material processing in recent years.
Compression Molding
The carbon fiber prepreg was placed between the upper and lower mold, and the mold was placed on the hydraulic molding table. After a certain period of high temperature and high pressure to cure the resin, the carbon fiber products were removed. This kind of forming technology has the advantages of high efficiency, good quality, high dimensional accuracy, less environmental impact and so on. It is suitable for the forming of mass and high strength composite parts. But in the early stage, the mold manufacturing is complex and the investment is high, and the size of the parts is limited by the size of the press.
Injection Molding
This is a new technology. EX MOULD Co., LIMITED Ltd is a leading supplier of custom Injection Moulding from China. Our injection molding equipment integrates the traditional “multi-step” process into a “one-step” process, which greatly shortens the process flow and better retains the fiber length, so as to achieve the purpose of energy-saving and efficient production. By overcoming a series of key technical problems in material equipment manufacturing, such as formula optimization, mixing system, intelligent control system and molding process parameter optimization, it can fully meet the requirements of automobile lightweight in terms of product strength, cost, efficiency, etc., and can be called as the best equipment tailored for automobile lightweight. Moreover, we provide packaging mold, hot runner mold and more high-quality molding services to meet all your demands.
Hand Lay Up
Apply the 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, after reaching the required thickness, form, solidify and demould. Nowadays, with highly developed preparation technology, hand paste technology is still widely used in many fields, such as petrochemical containers, tanks, automobile shells and so on. Its disadvantages are loose texture, low density, low strength products, and mainly rely on the artificial, unstable quality, low production efficiency.
Vacuum Autoclave
The composite blank made of single-layer prepreg in a predetermined direction is put into the autoclave, and the curing process is completed under a certain temperature and pressure. An autoclave is a kind of special pressure vessel which can bear and control certain temperature and pressure range. The blank is laid on the surface of the mold with a release agent, and then covered with porous anti-sticking cloth (film), adhesive absorbent felt, and breathable felt in turn, sealed in the vacuum bag, and then put into the autoclave. Before heating and curing, vacuum the bag to remove the air and volatiles, and then heat up, pressurize and cure according to the curing system of different resins. The formulation and implementation of the curing system are the keys to ensure the quality of autoclave parts.
Vacuum Induction
Vacuum induction is to lay “dry” carbon fiber composite material on the mold, then lay a vacuum bag, and draw out the vacuum in the system to form negative pressure in the mold cavity. By using the pressure generated by vacuum, the unsaturated resin is pressed into the fiber layer through the pre laid pipeline, so that the resin can infiltrate the reinforced material, and finally fill the whole mold. After the product is cured, the vacuum bag material is removed, Get the required products from the mold. In the vacuum environment, when the resin is infiltrated into the carbon fiber, there are few bubbles in the product. The product has higher strength and lighter weight, and the product quality is relatively stable. Moreover, the loss of resin is reduced. The product with smooth two sides can be obtained by using only one mold, which can better control the thickness of the product. It is generally used in rudder and radar shield of boat industry, blade and engine room cover of wind power, and all kinds of roof, windshield and carriage of the automobile industry.
3itech Induction Heating
A new type of induction heating technology with an inductor integrated into the mold can process carbon fiber at the temperature of 20 ℃ – 400 ℃. The inductor integrated into the mold can heat the surface of the mold through heat conduction. This is a supplementary technology introduced by roctool company in cage system, which uses electromagnetic induction to heat the mold quickly and control the local temperature well. The advantage is that the cycle time and component cost are significantly reduced. But at present, this technology is not suitable for large parts, and the related products must be large enough.
Lamination Molding
The prepreg layer by layer is placed between the upper and lower flat mould and heated and cured by pressure. This process can directly inherit the production methods and equipment of wood plywood, and improve and improve the resin according to the rheological properties of the resin. Lamination process is mainly used to produce various specifications and different uses of composite materials. It has the characteristics of high mechanization and automation, stable product quality and so on, but the one-time investment of equipment is large.
Pultrusion Molding
Under the action of traction, continuous carbon fiber tow, belt or cloth impregnated with resin liquid is molded and solidified by extrusion die to continuously produce profiles of unlimited length. Pultrusion is a special process of composite material forming, which has the advantages of automatic control and high production efficiency. The fiber mass fraction of pultruded products can be as high as 80%, and the dipping is carried out under tension, which can give full play to the role of reinforcing materials. The product has high strength, and the longitudinal and transverse strength of the finished products can be adjusted at will, which can meet the requirements of different mechanical properties of the products. The process is suitable for the production of profiles with various cross-section shapes, such as I-shaped, angle shaped, groove shaped, special-shaped cross-section pipes and composite cross-section profiles composed of the above sections.
