A study on the micro-injection molding of multi-cavity ultra-thin parts

In this study, we report the micro-injection molding of ultra-thin parts (100, 250, and 500 µm). The results show that the flow resistance increases as the cavity becomes thinner. The melt front is not symmetric when filling a four-cavity ultra-thin part and filling the eight-cavity mold under a low temperature. If we increase the mold temperature or cavity thickness, the melt front becomes symmetric. Finally, we construct the operation windows of molding for three kinds of plastics (PS, PMMA, PC) and provide a molding range based on mold temperature and injections speed. Meanwhile, the relationship between the thickness and the operation windows are also investigated. The thinner the cavity is, the smaller the operation window is. We need to increase the injection speed significantly for molding the ultra-thin parts with micro-features on both surfaces which are 60 µm in thickness. Furthermore, we succeed in molding 30 µm ultra-thin parts in this experiment. Copyright © 2009 John Wiley & Sons, Ltd.