Abstract: Experiment was carried out to study the effect of gate size and process parameters (eg. injection pressure and rate) on the melt filling behavior and tensile properties of PP injection molded parts in this paper. Three standard samples with rectangular gate of different size were taken as models, the filling process was observed by dynamic visualization experiment platform. By comparing and analyzing the melt filling behavior under different conditions, the conclusion was drawn that the gate size, injection rate and melt temperature significantly affected the filling speed of melt. The tensile test showed that the changes in the size of the gates would produce different influence on modulus and tensile strength of products. A suitable increase in the injection speed and pressure may improve the tensile properties of PP injection molding parts.

Key words: injection molding, gate size, polypropylene, filling behavior, tensile property