Thermal design of steel die for low pressure sheet molding compound

Heat transferring and thermal design of the steel die for low pressure sheet molding compound were analyzed and optimized by MATLAB software. The flexural properties of specimens, molded by normal and thermal deign optimized die respectively, were compared. In addition, the fracture surfaces were carefully analyzed by SEM. Results show that LPMC and traditional SMC differ in the heat transferring property. In the molding process, there occur phase transition by the decalescence of crystalline polyester. When the distribution of the heating pipes in the steel die was optimized, the surface temperature of the steel die was much even during the curing of LPMC, and the difference in temperature was limited in 3 °C. The flexural strength of the specimens, cut from the center and the corner of the parts molded by thermal optimized die, was almost the same. They could reach about 170 MPa.