Effect of process parameters on volumetric shrinkage of plastics via injection molding simulation /

Abstract

This thesis presents the injection molding (IM) process parameters’ optimization to reduce the shrinkage and sink marks from a plastic part through injection molding (IM) simulation. Many researches have been conducted in the past to optimize the effect of process parameters of IM process for different plastic parts. The part selected for this study is wheel cover which is commonly use in the automobiles. The four different materials used in this study for optimization are Acrylonitrile butadiene styrene (ABS), Polybutylene Terephthalates (PBT), Polypropylene (PP) and Acrylonitrile butadiene styrene blend - Polycarbonate (ABS/PC). The parameters selected for this study are melt and mold temperature, injection time, cooling time, packing time and packing pressure. 3D CAD model of the plastic part is made on SolidWorks® Plastics premium 2015 and Autodesk Simulation Moldflow® (ASM) Advisor 2014 is employed to carry out the injection molding simulation. A design of experiment (DOE) approach is used via Taguchi method to examine the effect of various process parameters on volumetric shrinkage and sink marks. An orthogonal array (OA) of L27 is applied to conduct the experiments. S/N ratio and analysis of variance (ANOVA) is used to find the quality, significance and percentage contribution of each processing parameter. Results show that ABS/PC material showed least shrinkage and sink marks. Process parameters i.e. melt temperature, mold temperature, packing time and packing pressure have substantial effects on volumetric shrinkage and sink marks. Melt temperature has the highest contribution in affecting both shrinkage and sink marks. Verification tests are being done, which shows that final optimized process parameters significantly reduce the volumetric shrinkage and sink marks for every material.