How PMI foam is processed
1. Molding process
The molding process is characterized by relatively high mold cost, and the advantage is that the thickness and size of the PMI foam composite material can be accurately guaranteed. At the same time, there are two components with smooth surfaces. The components that usually use the molding process include flight control components, helicopter rotors, and motion components. equipment and medical bed boards, etc. In the molding process, by giving the foam core a certain amount of interference, the interference provides a back pressure for the curing of the panel during the mold clamping and curing process.
The compression creep resistance of PMI foam is the premise and guarantee for the amount of interference to be converted into back pressure. By setting an appropriate amount of interference, the back pressure can be adjusted according to the resin content of the laminate, the curing system, and the thickness of the panel. , to meet the requirements of curing pressure.
2. Autoclave process
The autoclave process is characterized by a hard mold on one side and a soft mold (vacuum bag) on the other side. The curing composite laminate is pressurized by evacuation and pressurization in the autoclave. If the co-curing process is adopted, that is, the curing of the carbon fiber conformal material panel and the bonding of the sandwich structure core material and the panel are completed at one time. The gap of PMI foam is smaller than that of honeycomb, which can provide sufficient support for the curing of the panel, and will not have the telegraph effect like the honeycomb structure panel.
3. RTM process
Liquid resin injection is a relatively new optimized manufacturing process. With the help of RTM (Resin Transfer Injection Molding) technology, high-performance sandwich structural components are produced. At present, it is to simplify the production process, reduce manufacturing costs, save the price of raw materials, and select the price. Relatively low cloth with good laying properties can achieve mass production, and the components can use high-quality prepreg.
If the voids of the honeycomb are sealed so that the low-viscosity injection resin does not flow into the voids of the honeycomb, the honeycomb can also be selected as the sandwich material in the RTM manufacturing process. However, if the RTM process is used to produce the sandwich structure conforming material, the foam core material is generally used, and the core material also needs to have good compression creep resistance, which is the same as the autoclave process, and meets the requirements of resin injection pressure and injection temperature.