Thermal and Design Sensitivity Analyses for Cooling System of Injection Mold, Part 1: Thermal Analysis

In recent years, increased attention has been paid to the design of cooling systems in injection molding, as it becomes clear that the cooling system affects significantly both productivity and part quality. In designing the cooling system of a mold efficiently in terms of rapid and uniform cooling, it would be desirable for mold designers to have an optimal CAD system. For this optimal design, one needs capabilities of both a thermal analysis (to be discussed in Part 1) and a corresponding DSA (to be presented in Part II) for the 3-d mold heat transfer during the cooling stage of an injection molding process. It was found that seemingly negligible inaccuracy in the thermal analysis result sometimes leads to meaningless DSA result. With a successful DSA being an intermediate goal towards optimum design, we have improved the thermal analysis system based on the modified BEM in terms of accuracy and developed rigorous treatments of B.C.s appropriate for DSA by considering the following issues: (i) numerical convergency, (ii) the series solution in part thermal analysis, iii) treatment of tip surface of line elements, (iv) treatment of coolant, and (v) treatment of mold exterior surface. Using two examples, this paper amply demonstrates the importance of these issues.