Study on Packing Effects on the Part Shrinkage Molded by External Gas-Assisted Injection Molding process

摘要

External gas-assisted injection molding (EGAIM) has been receiving attention for its improvement of surface quality. However, compared with gas-assisted injection with gas penetration into the melt core, the packing effects of EGAIM on the pressure variation within the mold cavity and the part shrinkage have not been investigated. In this study, the pressure differential between core and cavity is about 3.04 bar. In addition, the required gas packing pressure (90 bar) is much lower than that of conventional packing pressure (1000 bar) in achieving identical shrinkage. With increased gas packing pressure and gas packing time, the shrinkage can be further reduced. However, the gas delay time for shrinkage is related to the pressure inside the mold.