EFFECT OF INJECTION SPEED ON GAS PENETRATION LENGTH, RESIDUAL WALL THICKNESS AND THE MELT FRONT POSITION DURING GAS-ASSISTED INJECTION MOLDING

摘要

Extensive experiments were conducted to study the effect of injection speed on gas penetration length, residual wall thickness, the melt front position and short-shot weight of gas-assisted injection molded part. Experiments were performed on polystyrene melts filling a spiral tube cavity at three different melt temperatures. Simultaneous measurements of the screw position and the evolution of gas pressure and melt pressure in the cavity were performed. At a constant shot size, the length of melt propagation and the weight of moldings were found to increase with an increase of injection speed. An implication of these finding for gas penetration in gas-assisted injection molding was discussed.