射出模內裝飾製程分析對精密塑膠複雜曲面之研究

A Study of Precision Plastic with Complex Surface by IMD Process Analysis

模內裝飾是一新型塑料裝飾技術，其優點為可有效減少產品後續裝飾製程，如噴塗、電鍍及雕紋等。以往的IMD技術普遍應用於曲率規則且變化不大的產品方面，直到近年來，由於克服裝飾薄膜的定位及曲面造成薄膜皺摺等問題，使得IMD技術能夠應用於塑膠外殼複雜曲面。一般IMD製程中最常見成型缺陷是因冷卻不均而產生翹曲變形，以及塑料充填造成薄膜沖刷及剪切應力問題。本研究目的是利用CAE模流分析工具來幫助解決複雜曲面於IMD製程中所產生的成型問題，並採用田口實驗方法，針對剪切應力問題作為主要探討重點，以迅速獲得製程參數對成型特性影響。分析結果顯示，影響剪切應力主要的製程參數為料溫、射出壓力及模溫。

In-Mold Decoration (IMD) is a new plastic decoration technology, which has the advantage of reducing the product follow-up decoration processes, such as spray painting, electroplating, sculpture lining, etc. Formerly the IMD decoration had been widely applied to 3C plastic products with regular surface curvatures. Until recently the film fixed position and film wrinkling problems of IMD due to curved surface have been overcome, the IMD technology makes treating the complex surfaces possible. Moreover, the common and usual defects during the IMD process are warpage defect created by non-uniform cooling, and film scour and shear stress problem due to plastic material filling process. The purpose of this study is to utilize the CAE mold flow analysis to solve forming problems of complex surfaces in the IMD process. In addition, the Taguchi method was used to evaluate the shear stress problem in order to maximize the process parameters. The testing results indicate that plastic temperature, injection time and mold temperature are key process factors influencing shear stress.