An experimental investigation of the effects of hot runner system on injection moulding process in comparison with conventional runner system

The effects of hot runner system on injection moulding process and properties of injected part have been investigated from various aspects in comparison with conventional runner system. A two-cavity mould which can be used for both of the runner systems was designed and produced so as to conduct all experiments on the same mould, and to compare the results precisely. In the experiments, acrylonitrile butadiene styrene and polypropylene materials were used as base polymers. Using the results obtained from the experiments, moulding area diagrams were plotted for both runner systems with respect to the process parameters of injection pressure and melt temperature changing within a wide range. It was observed that the required injection pressure was considerably lower to produce samples with higher weight in the case of hot runner system. The shrinkage and warpage increased with increasing process temperature, decreased with increasing injection pressure, and occurred at low level when the sample weight was high.