微量射出成型之充填特性觀察與玻璃微型模具可行性探討

• Main Author: 孫一強
• Other Authors: 楊申語
• Format: Others
• Language: zh-TW
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/20570013832607670536

碩士 === 國立臺灣大學 === 機械工程學研究所 === 89 === With the advance of MENS technology, replication of micro parts with injection molding becomes important. In the first part of this study investigates the filling capacity of a micro-injection molding system, which consists of a micro-mold and a pneumatic impact-type micro-injection molding machine. The processing parameters of this system include melt temperature, mold temperature, hammer weight and air pressure. The effects of process parameters on the flow length in various micro spiral channels are systematically studied. Mold temperature and hammer weight are found to be the most sensitive parameters. The effect of melt temperature increases with the thickness. In the second part of this study, a mold with two micro-plate cavities is constructed. Above the cavities is a transparent window, made of tempered-glass. A high speed video camera is employed to record the filling process. Filling processes with different design and processing conditions, such as gates, thickness, vacuuming are observed. With this impact-type injection molding machine, two kinds of filling are found: namely, immediate impact filling, followed by push filling. More than 15% of cavity is filled by immediate impact filling. Driven with high air pressure in a vacuumed cavity, as high as 70% of the cavity is filled with immediate impact filling. But the shape of melt front in a vacuumed cavity is irregular if the viscosity of melt is low. The smaller the gate angle is, the more steady is the shape of the melt front. When a hammer weight is added to the hammer head, almost 100% of cavity is filled by immediate impact filling. In the third part of this study, the possibility of using glass as mold material is discussed. Shrinkage is lower in a glass mold than in a steel mold. But the surface of the part molded in a glass mold is poorer than that in a steel mold, due to micro-holes left in the glass. The clamping pressure allowed with a glass mold is lower than with a steel mold.