Effect of Different Heating Methods on the Mold Temperature Control in the Plastic Injection Molding Process ☆

In this paper, electromagnetic induction heating is applied to attain a rapid mold surface heating. A mold surface had been heated to temperatures above the glass transition temperature with a heating time of 5.5 s, then the mold is closed for a melt injection and cooled down to ejection temperature before the next cycle starts. Different mold temperatures were applied to injection molding and the qualities of the associated parts including weld line appearance and weld line strength were examined. The results show that, with higher mold temperature, the surface appearance of a weld line can be reduced and the links of a weld line can be strengthened for molding double-gated tensile test parts. On the other hand, the rapid heating and cooling of mold surface temperatures using induction technology combined with low temperature coolant has a great advantage in comparison with the heater heating and hot water heating methods. By ANSYS simulation, the temperature distribution of three different heating methods was observed clearly, and this distribution has been supported by practical experiments. In addition, the application of induction heating for a cavity plate shows a better effect for weld line strength than for the core plate side