Integrated Simulations of Gas Injection Molding Process and Part Structural Performance under a Unified CAE Model

Integrated simulations of gas injection molding process and part structural performance under a unified CAE model were carried out. An analysis algorithm based on DKT/VRT elements superimposed with beam elements representing gas channels of various section geometries was first developed to evaluate the structural reinforcement of gas channel in the design stage. During melt/gas filling process, a mixed control-volume/finite-element/finite-difference method combined with dual-filling-parameter technique was implemented to trace the advancement of melt and gas fronts. For the prediction of secondary gas penetration, flow model of isotropic-shrinkage origin was introduced. Mold cooling analysis was executed utilizing cycle-averaged boundary element method considering the cooling system. Both cooling channel and the hollowed core gas channel were modeled using line-source approach. Thermal residual stresses calculated from part temperature distribution were then combined with the structural analysis to predict part warpage. The monitor support was used as the case study. The analysis accuracy from this unified model of 2-1/2D characteristics were examined experimentally. The only difference between process simulation and structure/warpage analyses is that different values of equivalent diameters assigned to a circular pipe representing gas channel should be used, respectively.