Research On The Mechanism Of The Occurrence Of Common Deffects In Gas-Assisted Injection Molding

Gas-assisted injection molding (GAIM) is an innovative injection technology evolved from the convention injection molding. It has a lot of advantage compared with the conventional injection molding, for it makes the best of the character of gas can transfer pressure equably because the viscosity of gas can be neglected compared with the viscosity of melt. However, GAIM becomes more complex with more molding parameter because of the induction of gas. There are a lot of defects, such as gas blows through melt front, short shot and gas fingering, in the molding produces if those molding parameters cannot be controlled properly.In this paper, the simulation of the mechanism of the occurrence of these deffects in the GAIM is studied by using MOLDFLOW software, They are verified with experiment data. The studies of the paper is as follows:1. On the basis of rational hypothesis, the mathematical models are established for the mold-cavity filling flow of GAIM.2. The effect principles of different materials and technology parameters on three defects, such as melt blow through, short shot and fingering effect are studied with simulation and experiments,3. The influence of different gas channel distribution and size on fingering effect is simulated and analyzed.4. By comparing the simulation results with experiment data, the influence factors of three defects including melt blow through, short shot and gas fingering are achieved.5. The countermeasures are offered to avoid three defects.