Visual Computer-based Simulation Of Residual Stress In Sandwich Injection Molding

As a new injection molding technology, avoiding or reducing residualstress of co-injection products is quite significant for its application as wellas theoretic study of sandwich injection molding.The residual stress is one of the most important reasons, whichdirectly results in the shrinkage and warpage. Therefore, if we can figureout the development law of the residual stress and establish an effectivecalculating model, it will boost the research of this field and highlyimprove the products qualities. This thesis is concentrated on theexperimental analysis of amorphous material.On the chance of understanding the melt flow behavior and themechanism of sandwich injection molding, we made dynamic simulationresearches on sandwich injection molding process by employing theco-injection module in the software of Moldfiow Plastics Insight.In this study, factors effecting residual stress of co-injection productswere investigated by changing materials and their viscosity ratio, processparameters such as injection rate, packing pressure, mold temperature andmelt temperature etc..It was realized that the behavior of residual stresses in injectionmolding parts was affected by the kind of materials and different processconditions such as melt temperature, mold temperature, packing pressureand filling time. It was found that two materials' compatibility determinesthe core/skin melts interface residual stress distribution; core/skin viscosity ratio also influences residual stress distribution. The packing condition isthe most important factor that affects the residual stresses of all processconditions, followed by injection rate and melt temperature, and moldtemperature is the least. The most greatly residual stress mainly distributesin the position of core and core front, while the residual stress of spur andskin is smaller.