Simulations of gas penetration in thin plates designed with a semicircular gas channel during gas-assisted injection molding

Numerical simulations and experimental studies concerning gas and melt flows during gas-assisted injection molding of a thin plate designed with a gas channel of semicircular cross section were conducted. Distribution of the skin melt thickness along the gas penetration path was measured. Melt and gas flows in a gas channel of semicircular cross section were approximated by a model which uses a circular pipe of equivalent diameter superimposed or the thin plate. An algorithm based on the control-volume/finite-element method combined with a particle-tracing scheme using a dual-filling-parameter technique was utilized to predict both melt front and gas front advancements during the mold filling process. Simulated distribution of gas penetration shows reasonably good coincidence with the experimental observations.