Effects of molding conditions on transcription molding of microscale prism patterns using ultra‐high‐speed injection molding

Abstract

AbstractIn this study, we performed a series of molding tests to investigate the potential of microscale transcription of polymer by ultra‐high‐speed injection molding (UHSIM). During the tests, the injection speed was varied up to a maximum of 995 mm/s. Polymethyl methacrylate was molded under various injection molding conditions, including cavity vacuum pumping process, so as to replicate an electroformed nickel stamper exhibiting V‐grooves with a pitch of 50 μm. Surface configurations of molded samples were observed and measured using a laser scanning microscope. The transcription ratio (TR) is defined as the ratio of the depths of V‐grooves in both the molded samples and the stamper. An excellent average TR of 0.97 was performed when molding at an injection rate of 800 cm3/s (injection speed of 995 mm/s), mold temperature of 80°C, and holding pressure of 120 MPa. In addition, the effect of vacuum on transcription molding was investigated in detail; the result proved that vacuum is an important factor in the enhancement of transcription fidelity. The strong influence of injection rate on the TR indicates the applicability of UHSIM to the field of transcription molding of polymers. POLYM. ENG. SCI. 46:1140–1146, 2006. © 2006 Society of Plastics Engineers.