POLYMER MELT FLOW AND GAS PENETRATION IN GAS-ASSISTED INJECTION-MOLDING OF A THIN PART WITH GAS CHANNEL DESIGN

Numerical simulations and experimental studies concerning gas and melt flow during gas-assisted injection molding of a thin, angle bracket p art with gas channel design were conducted, Distribution of skin melt thickness along the gas flow direction was measured. Melt and gas flow within the gas channel of a quadrantal cross-section is approximated by a model which uses a circular pipe of equivalent hydraulic diameter superimposed on the thin part. An algorithm based on a control-volume /finite-element method combined with a particle-tracing scheme suitabl e for two-component flow front advancements is utilized and numericall y implemented to predict both melt and gas front advancements during a molding process. Simulated results on the distribution of gas penetra tion show reasonably good coincidence with experimental observations. Copyright (C) 1996 Elsevier Science Ltd.