Effects of cooling time of molded parts on rapid injection molds with different layouts and surface roughness of conformal cooling channels

The main factor affecting the productivity of a new product in the injection molding process is the cycle time. In general, the productivity of a new product can be enhanced by shortening the cooling time because the cooling time occupies most of the cycle time. The cooling time can be shortened by an injection mold with conformal cooling channels which are conformal to the molding cavity. In this study, six injection molds with different locations of cooling channels and six injection molds with different surface roughness of cooling channels were fabricated for low-pressure wax injection molding. It was found that the cooling time of the molded part (y) can be directly predicted from the center distance with respect to mold cavity (x) according the trend equation of y=141.49 ln (x)+733.03. The cooling time of the molded part is shorter when the center distance with respect to mold cavity is closer smaller. The optimal distance between the wall of the conformal cooling channel and the surface of the injection mold is 2mm based on the productivity of a new product. In addition, the surface roughness of the cooling channel wall is as small as possible when the flow of the coolant is completely turbulent.