EFFECTS OF PROCESS PARAMETERS ON SHRINKAGE UNIFORMITY AND BIREFRINGENCE OF INJECTION-COMPRESSION MOLDED PARTS

摘要

Injection-compression molding (ICM) with greater flexibility than conventional injection molding (CIM) can produce parts with better quality. In this work, polystyrene (PS) parts were molded by ICM technology. The effects of seven dominating process parameters, including mold temperature, melt temperature, compression force, compression distance, compression speed, compression time, and delay time, on both shrinkage uniformity and birefringence of PS parts were investigated. The results showed that compression force is the most important parameter for part shrinkage uniformity. The position with a lowest shrinkage moved towards the gate with increased compression distance. There is a remarkable increase in birefringence with larger compression forces. There is certain relationship between shrinkage uniformity and birefringence results.