Optimization of process parameters in rapid heat cycle molding using heater system

Abstract

Plastic injection molding (PIM) is a manufacturing technology to plastic products. In PIM, weldline that affects the strength and surface quality of products, and it is then important to determine the optimal process parameters for the weldline reduction. Rapid heat cycle molding (RHCM) is an attracted PIM technology for weldline reduction that by heating up the mold temperature, the melt plastic is smoothly flowed into the die cavity and consequently the weldline is well reduced. In RHCM, since various heating systems are adopted but which have problem that long cycle time. In this paper, to quickly heat up the mold temperature, a heater system is newly introduced and the process parameters in the RHCM using heater system are optimized. A multi-objective optimization for minimizing both weldline and cycle time is considered, and the ratio of mold temperature to injection time is maximized for the weldline reduction, whereas the cycle time is minimized for high productivity. Sequential approximate optimization that the response surface is repeatedly constructed and optimized is adopted for the design optimization, and the pareto-frontier is identified. Based on the numerical result, the experiment is also conducted to examine the validity of the proposed RHCM.