Computer simulation of the injection mold cavity filling process
Polimery 2002, No 2, 122
Filling of the injection mold cavity was analyzed in relation to the feeding mode: (i) at one end, (ii) simultaneously at the two ends of the cavity. The CAE C-Mold ver. 99.1 routine was used to simulate the flow of HDPE through the injection mold equipped with the cavities used to form standard (PN-EN ISO 527:1998) tensile bars. The feeding mode was found to play an essential role: in mode (ii), the polymer pressure required for the cavity to be completely filled was by 30% lower than in mode (i) (Fig. 4), because the pathway of flow was shorter and the resistance to flow was reduced. The modes (i) and (ii) result in differentiated distributions of pressures and temperatures (Fig. 5) along the molded piece axis, and they variously affect the distribution of residual stresses in, and the shrinkage and warpage of, the solidified molded piece. Again, the shear rate is higher in mode (i) than in (ii) (Fig. 6) and affects the structure of the molded piece and hence also its properties. Simulations of the melt front displacement in the cavity enable the cavity filling process and its effect on the properties of the molded pieces to be better understood. In mode (ii), simulations make it possible to determine the position of the weld line.
Keywords: injection molding, filling of injection mold cavity, computer simulation