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. Distr ibution of the skin melt thickness along the gas penetration path was measured. Melt and gas flows in a gas channel of semicircular cross se ction were approximated by a model which uses a circular pipe of equiv alent diameter superimposed or the thin plate. An algorithm based on t he control-volume/finite-element method combined with a particle-traci ng scheme using a dual-filling-parameter technique was utilized to pre dict both melt front and gas front advancements during the mold fillin g process. Simulated distribution of gas penetration shows reasonably good coincidence with the experimental observations.