Jea Gu Lee,

Journal of Advanced Technology Research, Vol. 2, No. 1, pp. 1-5, Jun. 2017
10.11111/JATR.2017.2.1.001, Full Text:
Keywords: Micro injection molding, Micro structures, Numerical analysis
Abstract

Experimental and numerical studies were carried out to investigate the processing ability of the injection molding of micro structures. For this purpose, we designed a mold insert having micro rib patterns on a relatively-thick ground plate. The mold insert has a base of 2 mm thickness, and has nine micro ribs on the ground plate. Width and height of the micro rib are 300 μm and 1200 μm, respectively. We could find a phenomenon similar to “race tracking”, due to “hesitation” in the micro ribs. As the melt ows, it starts to cool down and melt front located in the ribs near the gate cannot penetrate further because of large ow resistance in that almost frozen portion. When the base is totally lled, the melt front away from the gate is not frozen yet. Therefore, it ows back to the gate direction through the ribs. Consequently, transcriptability of the rib far from the gate is better. We also veri ed this phenomenon via numerical simulation. We further investigated the effects of processing conditions, such as flow rate, packing time, packing pressure, wall temperature and melt temperature, on the transcriptability. The most dominant factor that a ects the ow pattern and the transcriptability of the micro rib is ow rate.

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