Simulation of injection-compression mold-filling process

[[abstract]]A numerical algorithm is developed to simulate the filling state of injection-compression molding (ICM) process. Hele-Shaw fluid flow model combined with the control-volume/finite-element (CV/FEM) method is implemented to predict the melt front advancement and the distributions of pressure, temperature and flow velocity dynamically during the melt-filling process. Processing characteristics were understood by changing processing parameters including compression speed, switch time from injection to compression, compression stroke as well as initial cavity thickness using disk parts. The simulated molding pressures were also compared with those required by conventional injection molding (CIM) assuming the same entrance flow rate. It was found that the compression speed and compression stroke are the two factors affecting the molding pressure most significantly. Switch time also shows apparent effect on the pressure profiles. Using higher switch time, lower compression speed and higher compression stroke will result in lower cavity pressures. The melt velocity far from the gate was found to be higher than that near the gate during the compression stage contrary to that of CIM resulting in different part residual stress and melt temperature distribution. The simulated pressures for both ICM and CIM show good coincidence with those obtained from cavity pressure measurements