Computer simulation for injection-moulding applied to amorphous thermoplastic ABS

Abstract

A comparison between the pressure predicted by the Moldflow R simulation software and measured during the injection moulding experiment was made to study the effects of injection moulding parameters on impact performance. The simulation was investigated for the Moldflow standard database and personal database which was prepared by testing of ABS properties. The cavity pressures of rectangular plaque mould were measured by two pressure transducers fitted near the gate and far from the gate. The comparison was made using three grades of amorphous thermoplastic ABS. For the study of the effects of injection moulding parameters on the impact properties, two important influence parameters were the injection speed and melt temperature. Increasing injection speed increased the impact properties which caused by molecular degradation. Low melt temperature gave slightly reduction in impact properties because of higher internal stress. The simulation which the material information input was Moldflow standard database or personal database showed insignificant difference of the predicted pressure for Lustran 250. For Lustran 440 and Lustran 640, the simulation predicted higher pressure values as personal database was selected. The simulation was done by the selection of Moldflow standard database for ABS 250 to compare with the measurement. The simulation showed disagreement to the measurement. The fill times were different from the measured values. The differences in the prediction were attributed to the over-estimation of the cooling rate of Moldflow. The experimental mould had very simple cooling system which possibly was inefficient in terms of Moldflow software design assumptions. In addition, Moldflow could over-estimate the shear-heating during the injection phase of nozzle, runners and gate system