The final product molding factors include prepreg, hot press, working mold, working environment, on-site temperature, relative humidity, etc. The most important thing is the process of curing the prepreg into a product in the cavity after it is molded. It is The result of the combined effect of pressure, temperature and holding time. This article focuses on analyzing the influence of pressure, temperature, time, volatiles and other factors on the molding process.
The carbon fiber composite material compression molding process is to put a certain amount of pre-pretreated prepreg into the mold cavity, apply a certain pressure to make the prepreg fill the cavity, and under a predetermined temperature condition, the prepreg is in the cavity The interior is gradually solidified, and then the carbon fiber composite product is taken out of the mold, and necessary post-processing is performed to obtain the final carbon fiber composite product.
The final product molding factors include prepreg, hot press, working mold, working environment, on-site temperature, relative humidity, etc. The most important thing is the process of curing the prepreg into a product in the cavity after it is molded. It is The result of the combined effect of pressure, temperature and holding time. This article focuses on analyzing the influence of pressure, temperature, time, volatiles and other factors on the molding process.
1. Mold pressure
The pressure can accelerate the flow of the prepreg in the mold cavity, increase the density, overcome the pressure generated by the low molecular substances released during the resin matrix polycondensation reaction, and avoid swelling and delamination. At the same time, the molding pressure can also close the tooling and molds. It has the functions of fixing the size and preventing deformation during cooling.
The molding pressure depends on the type of prepreg, the shape of the product and the state of the prepreg. If the fluidity of the prepreg is smaller, the curing speed is faster, the compression ratio is greater, and the pressure required is greater; on the contrary, the pressure required is smaller. In the molding process of molded products, temperature and pressure are interrelated. Increasing the mold temperature can increase the fluidity of the prepreg. For example, reducing the molding pressure during the period from the beginning of the molding to the greater fluidity can also achieve the desired goal.
2. Temperature
During the compression molding process, the flow, filling, and curing reaction speed of the prepreg are closely related to the temperature, and the temperature plays a major role in the compression molding process. It affects the degree of crosslinking of the resin matrix and therefore also affects the composite material. Final product performance.
Practice has also shown that increasing the mold temperature can speed up the curing speed and shorten the curing time, but too high temperature will cause the prepreg to quickly reduce its fluidity due to the curing speed being too fast, causing dissatisfaction with the filling, especially for large thin walls and shapes. For complex composite products, when the temperature is too high, the outer layer of the product solidifies much faster than the inner layer, which makes it difficult to eliminate the volatiles in the inner layer, which reduces the physical and mechanical properties of the product, and also causes defects and deformation of the product. When the curing temperature is too low, the curing temperature will be slow and the curing degree will be low.
3. Molding time
The molding time is related to the type of prepreg, volatile content, product shape, thickness, tooling and mold structure, molding temperature, pressure and other factors. The length of the molding time has a great influence on the performance of the product. The molding time is too short, the curing is incomplete, the physical and mechanical properties of the product are low, the surface roughness is poor, and the product is prone to deformation. The increase of molding time can reduce the shrinkage and deformation of the product, but it should be noted that the molding time is too long, the resin crosslinks excessively, and the internal stress of the product will increase, so choose the appropriate molding time.
4. Volatile matter
During the molding process, the volatile content has a great influence on the fluidity of the prepreg. The volatile content is large, the fluidity of the prepreg is large during the horizontal pressing time, and the excessively high volatile content makes the prepreg too fluid, causing the loss of the resin matrix, the production of bubbles, and the reduction of surface roughness. However, the volatile content is too high Low will also reduce the fluidity of the prepreg, making it difficult to form composite products.
In the composite material molding process, the final inspection is only a judgment on the quality of the product, and cannot be traced back. The control of each process in the molding process is the key to ensuring the production of qualified products. The servo composite molding machine produced by Pengda Hydraulic is equipped with a touch control screen, which realizes real-time monitoring and adjustment of molding pressure, temperature and time during the production process to ensure the yield and quality of the finished product. You are welcome to inquire: 0510-83394311, email: cindy@wuxipd.com
