Study Of "Gas Fingering" Behavior In Gas-assisted Injection Molding

A new molding technique, gas-assisted injection molding (GAIM) which is capable of produced parts having both thick and thin sections, with structured rigidity and not sacrificing surface quality, has received extensive attention in recent years. In this process, molten plastics are injected into a mold followed by an injection of pressurized nitrogen gas into the core of the melt to produce hollow parts. Despite some lacunas in the practical application of GAIM process, it offers a number of advantages over conventional injection molding (CIM).â‘ GAIM can substantially reduce cycle time. The melt injection time and cool time are decreased, the pressure packing time is eliminated. It is propitious to reduce parts cost.â‘¡GAIM can reduce the clamp tonnage greatly. During the CIM, clamp tonnage must large enough to meet the needs of packing stage, especially to solve the problem of sink marks. However, the low gas pressure is needed for packing in GAIM, thus, the clamp tonnage is reduced.â‘¢GAIM can save material. The first stage of this process is shot short, so the material is saved.â‘£GAIM can eliminate the lacunas of parts greatly. Part quality can be improved by reducing residual the stress, warpage, sink marks and shrinkage that are normally encountered in CIM. Focused on the formation mechanism of gas bubble blemish inside the gas channel wall for a GAIM part, the main study results are summarized as follows:1. Research on effect of gas-assisted injection molding processing parameters on parts gas fingering defect Gas fingering defects in GAIM parts are investigated with the methods of numerical simulation and orthogonal experiment in the paper. The influenced connections of six different processing...