The cooling phase takes the longest time in injection molding process. Subsequently, researchers are focusing on the reduction of cooling time in injection molding process. Appropriate screw design in injection molding machine is required to enhance plasticizing plastics in a short cooling time. In this study, the effects of two barrier screw designs, open and closed barrier flights, on the plasticization efficiency of polypropylene (PP) resin were investigated through melting experiments. Throughput, back pressure, torque, and melt temperature for RPM were measured after screw operation reached a steady state. And the melting behaviors of PP resin were examined by observing the distribution of materials in the screw channels after the screws were removed from the barrel. Plasticizing capability was measured and compared in terms of melting length, the distance between the starting and completion points of melting.

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