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Investigation of the Filling Unbalance and Dimensional Variations in Multi-Cavity Injection Molded Parts  

Kang, Min-A (The Graduate School of Industry and Engineering, Seoul National University of Technology)
Lyu, Min-Young (Department of Die & Mould Engineering, Seoul National of Univ. of Technology)
Publication Information
Polymer(Korea) / v.32, no.6, 2008 , pp. 501-508 More about this Journal
Abstract
Small injection molded articles such as lens and mobile product parts are usually molded in multi-cavity mold. The problem occurring in multi-cavity molding is flow unbalance among the cavities. The flow unbalance affects the dimensions and physical properties of molded articles. First of all, the origin of flow unbalance is geometrical unbalance of the delivery system. However, even the geometry of the delivery system is well balanced, cavity unbalance occurs. This comes from the temperature distributions in the cross-section of runner. Temperature distribution depends upon injection speed because heat generation near runner wall is high at high injection speed. Among the operational conditions, injection speed is the most significant process variable affecting the filling unbalances in multi-cavity injection molding. In this study, experimental study of flow unbalance has been conducted for various injection speeds and materials. Also, the filling unbalances were compared with CAE results. The dimensions and weights of multi-cavity molded parts were examined. The results showed that the filling unbalances vary according to the injection speeds and resins. Subsequently, the unbalanced filling and pressure distribution in the multi-cavity affect the dimensions and physical states of molded parts.
Keywords
filling unbalance; multi-cavity injection mold; delivery system; runner balance; injection speed;
Citations & Related Records
Times Cited By KSCI : 2  (Citation Analysis)
Times Cited By Web Of Science : 2  (Related Records In Web of Science)
Times Cited By SCOPUS : 2
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