A SIMPLE MODEL FOR EVALUATION OF CONTRIBUTION FACTORS TO SKIN MELT FORMATION IN GAS-ASSISTED INJECTION MOLDING

摘要

A simple formulation based on a non-isothermal power-law fluid model was derived in order to evaluate the effect of various processing parameters as well as melt rheological behavior on the skin melt formation during gas-assisted injection molding. From this model, effect of molding conditions including melt temperature, mold temperature, delay time and gas injection pressure as well as shear-thinning behavior of polymer melt on the formation of skin melt thickness was numerically evaluated in a quasi-quantitative manner. Calculated results from this model predict similar dependence of skin thickness variation on contributing parameters as those observed from experiments. The analysis also indicates that the transient nature of melt flow caused by gas penetration may exist in actual molding process. [References: 17]