1. Autoclave process
It is characterized by a hard mold on one side and a soft mold on the other side. The curing composite laminate is pressurized by evacuation and pressurization in the autoclave. If the PMI foam adopts the co-curing process, that is, the curing of the carbon fiber composite 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.
2. The molding process
The cost of the mold is relatively high, and the advantage is that it can accurately ensure the thickness and size of the composite material, and has two components with smooth surfaces at the same time. The components that usually use the molding process include flight control components, helicopter rotors, sports equipment and medical bed boards. In the molding process, by giving the foam core a certain amount of interference, the interference provides a back pressure to 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.
3. RTM process
Liquid resin injection is a relatively new optimized manufacturing process. With the help of RTM technology, high-performance sandwich structural components are produced. At present, in order to simplify the production process, reduce manufacturing costs, and save the price of raw materials, the selected price is relatively low and has good quality. The cloth with high cladding performance can realize mass production, and the components can achieve the effect of using 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. Similar to the autoclave process, the core material also needs to have good compression creep resistance and meet the requirements of resin injection pressure and injection temperature.