2008 年 74 巻 1 号 p. 67-71
This study aims to develop an injection molding technology for micro plastic parts below several μm in size. An ultra high speed injection molding machine applying dropping force of weight, which performs high speed injection using the impact load of a free-fall weight, and a focused ion beam fabrication machine were used to fabricate micro molds, and attempts were made to fabricate micro plastic parts 50μm in size. To achieve the fabrication of parts in micro order size, investigations were particularly carried out on cavity insert structure and mold structure including the material. The results showed that the WC-Co cavity insert is more appropriate for molding compared to Ni plating cavity insert which has problems such as deformation of the runner and gate and micro cavities as well as flush of the molded product. Using the WC-Co cavity insert, star-shaped products of 50μm in maximum size with little flash were successfully fabricated.