Interactions of Polymer Material, Mold Design and Process Condition in Micro Molding Process
Jianhong Zhao, Ge Chen, Poh Sing Chan, Marcin Debowski
Singapore Institute of Manufacturing Technology
Singapore

Keywords: micro molding, polymer, mold design

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The rapid development of microsystem technology in recent years has placed increasing demands for production of miniaturized components for various MEMS device applications. Due to the advantages of polymer materials such as easy mass processing and tailorable properties, the micro molding process is increasingly becoming a key enabling technology for microsystems. In order to produce micro parts that weigh no more than a few milligrams in a reliable and economical way, micro molding machines that use a small diameter plunger injection system for melt injection and control have been developed and used in the molding industry. In the present paper micro molding studies have been carried out using a Battenfeld Microsystem injection molding machine with a maximum melt injection capacity of 1 cm3. Micro molds with different runner and gate designs were used to study melt shear effect during the process. Both amorphous and crystalline polymers, including PMMA, PC, POM, PBT, and LCP were evaluated in the study. It has been found that, while the metering size is the dominating factor which affects the process, the mold temperature, melt temperature and injection speed can also affect the mold filling behavior. Shrinkage and the speed of melt solidification are the two important material factors that need to be considered in the process condition setting. Since micro runner and cavity system solidifies very quickly in the micro molding process, a high shrinkage and quick melt solidification may results in short shot or high micro part distortion.