Carbon fiber composite materials need to be processed using a molding process from prepreg to final part. With the development of carbon fiber technology, the molding process of carbon fiber composite materials is also constantly improving. However, various molding processes of carbon fiber composite materials do not exist in the way of updating and eliminating, and often a variety of processes coexist to achieve the best results under different conditions and circumstances. good effect. The following is a list of the 12 most commonly used carbon fiber composite molding processes at this stage, and see which ones you know.
injection molding process
It belongs to a type of low-pressure molding in the hand lay-up process. After mixing chopped fiber and resin with a spray gun, compressed air is sprayed on the mold, and after reaching a predetermined thickness, it is manually pressed with a rubber roller, and then cured and formed. A semi-mechanized molding process created to improve hand lay-up molding has a certain degree of improvement in work efficiency, but it still cannot meet mass production. It is used to manufacture transition layers for automobile bodies, ship hulls, bathtubs and storage tanks.
Winding
The process of winding continuous fibers or cloth tapes impregnated with resin glue on a core mold according to a certain rule, and then curing and demoulding into composite products. Carbon fiber winding molding can give full play to its characteristics of high specific strength, high specific modulus and low density.
liquid molding
Synthesize liquid monomers into high-molecular polymers, and then change from the process of polymer curing reaction to composite materials to be completed directly in the mold at one time, which not only reduces the energy consumption in the process, but also shortens the molding cycle (only It takes about 2 minutes to complete a product). However, the application of this process must be based on precise pipeline transportation and metering, as well as automatic temperature and pressure control.
Liquid molding mainly includes: RTM molding process, RFI molding, VARI molding.
The main advantages of the resin film infiltration (RFI) molding process are that the mold is simpler than the RTM process mold, the resin flows along the thickness direction, it is easier to infiltrate the fibers, there is no prepreg, and the cost is lower. However, the dimensional accuracy and surface quality of the obtained products are not as good as those of the RTM process, the void content is higher, and the efficiency is slightly lower, which is suitable for the production of parts with large planes or simple curved surfaces.
The advantages of the vacuum-assisted forming process (VARI) are high utilization rate of raw materials, less trimming and processing, no need for prepregs, and low cost. It is suitable for the production of large-scale panel structural parts at room temperature or low temperature. But the disadvantages are similar to the RFI molding process.
Resin Transfer Molding (RTM)
Resin Transfer Molding (RTM: Resin Transfer Molding) technology is a low-cost manufacturing method of composite materials, originally mainly used for aircraft secondary load-bearing structural parts, such as doors and inspection hatches. In 1996, the US Defense Advance Research Agency carried out research on low-cost RTM manufacturing technology of high-strength main bearing components. RTM technology has the advantages of high efficiency, low cost, good quality of parts, high dimensional accuracy, and little impact on the environment. It can be applied to the molding of composite parts with large volume, complex structure and high strength. One of the most active research directions in the field of material processing.
Compression molding
The carbon fiber prepreg is placed between the upper and lower molds, and the mold is placed on the hydroforming table. After a certain period of high temperature and high pressure to solidify the resin, the carbon fiber product is removed. This molding technology has the advantages of high efficiency, good product quality, high dimensional accuracy, and less environmental impact, and is suitable for the molding of mass and high-strength composite parts. However, in the early stage, the mold manufacturing is complex, the investment is high, and the size of the parts is limited by the size of the press.
injection molding
This is a new type of technology. Bole CIML equipment integrates the traditional "multi-step method" process into "one-step method", which greatly shortens the process flow, and better retains the fiber length to achieve the purpose of energy-saving and high-efficiency production. By overcoming a series of key technical problems such as formula optimization, compounding system, intelligent control system and molding process parameter optimization in materials-equipment-manufacturing, it fully meets the requirements of vehicle lightweighting in terms of product strength, cost, and efficiency. A weapon tailored for the lightweight of automobiles.
injection molding
This is a new type of technology. Bole CIML equipment integrates the traditional "multi-step method" process into "one-step method", which greatly shortens the process flow, and better retains the fiber length to achieve the purpose of energy-saving and high-efficiency production. By overcoming a series of key technical problems such as formula optimization, compounding system, intelligent control system and molding process parameter optimization in materials-equipment-manufacturing, it fully meets the requirements of vehicle lightweighting in terms of product strength, cost, and efficiency. A weapon tailored for the lightweight of automobiles.
Hand lay-up--wet lay-up method
Apply mold 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, and after reaching the required thickness, form, solidify and demould. Today, when the preparation technology is highly developed, the hand lay-up process is still widely used in many fields such as petrochemical containers, storage tanks, automobile shells, etc. due to the advantages of simple process, low investment and wide application. The disadvantage is that the texture is loose, the density is low, the product strength is not high, and it mainly depends on labor, the quality is unstable, and the production efficiency is very low.
Vacuum autoclave
The composite material blank formed by laying up a single layer of prepreg material in a predetermined direction is placed in an autoclave, and the curing process is completed under a certain temperature and pressure. An autoclave is a special pressure vessel that can withstand and regulate a certain temperature and pressure range. The blank is laid on the surface of the mold with release agent, then covered with porous release cloth (film), absorbent felt, and air felt in sequence, sealed in a vacuum bag, and then placed in an autoclave. Before heating and curing, vacuum the bag to remove 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 is the key to ensuring the quality of autoclaved parts.
Suzhou Noen Composites used the autoclave molding process when customizing a military transport box for a military enterprise. The manufactured military transport box has a smooth appearance and stable structure, and finally passed the military's acceptance audit. The vacuum autoclave forming process has many advantages. Not only can laminates of different thicknesses and parts with complex curved surfaces be cured, but the mechanical properties are also very reliable. However, the corresponding vacuum autoclave forming also has some disadvantages. For example, the size of the parts is affected by hot pressing Tank size constraints and high energy consumption result in high operating costs.
Vacuum introduction
VIP for short, lay "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 pass the unsaturated resin through the pre-laid pipeline. Press into the fiber layer, let the resin infiltrate the reinforcing material, and finally fill the entire mold. After the product is cured, remove the vacuum bag material and obtain the desired product from the mold.
In the vacuum environment, the resin infiltrates the carbon fiber, and there are very few bubbles in the product. The product has higher strength, lighter weight, stable product quality, and reduces the loss of resin. Only one side of the mold can be used to obtain smooth and flat products on both sides. , can better control the product thickness. It is generally used in rudders and radar shields in the marine industry, blades and cabin covers in wind power energy, and various types of roofs, windshields, and carriages in the automotive industry.
3iTech induction heating
A new type of induction heating process that integrates an inductor into the mold, which can process carbon fibers at a temperature of 20°C-400°C, and heat the surface of the mold with an inductor integrated inside the mold through heat conduction. This is a complementary technology introduced by the start-up company RocTool on the Cage system. The use of electromagnetic induction can rapidly heat the mold and can control the local temperature well. The advantage is a significant reduction in cycle times and component costs. However, this technology is currently not suitable for large components, and the relevant production volume must be large enough.
Lamination
The layer-by-layer prepreg is placed between the upper and lower flat molds for pressure heating and curing. This process can directly inherit the production methods and equipment of wood plywood, and improve and perfect it according to the rheological properties of the resin. The lamination molding process is mainly used to produce composite sheets of various specifications and uses. It has the characteristics of high degree of mechanization and automation, and stable product quality, but the one-time investment in equipment is large.
pultrusion
Under the action of traction, the continuous carbon fiber tow, belt or cloth impregnated with resin glue is formed and cured by extrusion die to continuously produce profiles of unlimited length. Pultrusion is a special process in the composite material forming process. Its advantages are that the production process can be fully automated and controlled, and the production efficiency is high.
The fiber mass fraction in pultruded products can be as high as 80%. The dipping is carried out under tension, which can fully play the role of reinforcing materials. performance requirements. This process is suitable for producing profiles with various cross-sectional shapes, such as I-shaped, angle-shaped, groove-shaped, special-shaped section pipes, and combined section profiles composed of the above-mentioned sections.
Suzhou Noen Composites has been focusing on the carbon fiber field since its establishment. It is not only equipped with complete carbon fiber core production equipment, such as carbon fiber thermoforming machines, autoclave curing furnaces, etc., but also has established a dedicated laboratory to analyze innovative functional materials. And R & D, in the carbon fiber industry, has been adhering to the principle of customer first, to provide customers with more high-quality carbon fiber products.
Post time: Jun-10-2022