Chapter 5: Cooling Simulation

Yun Zhang, and Huamin Zhou

State Key Laboratory of Materials Processing and Die & Mould Technology, Huazhong University of Science and Technology, Wuhan, Hubei, China

5.1 Introduction

The injection molding process can be generally classified into three stages, namely, filling, packing (or postfilling), and cooling. The cooling stage takes about 80% of the total cycle, and it is the only stage that can be considerably reduced by using better mold design. In the plastic injection molding, the cooling system design affects not only the production efficiency but also the quality of final products. A rapid cooling improves process economics by shortening the cycle time. Meanwhile, a uniform cooling improves product quality by preventing differential shrinkage, internal stresses, part warpage, and mold release problems, as well as shorten the molding cycle.

There are various ways to provide coolness to the injection mold. The cooling system mainly considered in the present study is the widely employed cylindrical cooling channels that provide passages of coolant such as water and synthetic oil. The coolant is continually running along cooling channels, in general, or flows only after the polymer melt fills the cavity; thus, when the melt enters the mold, it is not subjected to a fast cooling shock. Generally speaking, the major concern of the cooling system design lies in finding the best arrangement of the cooling channels and the best combination of cooling ...

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