Abstract
Weldline that has an influence on not only the appearance but also the strength of plastic product is one of the crucial defects in plastic injection molding (PIM). It is important to reduce it as much as possible for high product quality. In addition, high productivity that is short cycle time is also required in PIM. To minimize the weldline and the cycle time for high product quality and productivity, process parameters such as melt temperature, injection velocity, packing pressure and so on should be adjusted and optimized. For more effective weldline reduction, variable injection velocity and variable packing pressure that are injection velocity or packing pressure vary during the PIM are adopted. Besides, a new weldline evaluation instead of weldline length is proposed. In this paper, a multi-objective optimization of variable injection velocity, variable packing pressure and process parameters is then performed for the weldline reduction and the short cycle time. A sequential approximate optimization using Radial basis function (RBF) network is used to identify the pareto-frontier. The experiment using the PIM machine (GL100, Sodick) is conducted. Though the numerical and experimental result, the validity of the proposed approach is examined.
