Mold‐filling studies for the injection molding of thermoplastic materials. Part I: The flow of plastic materials in hot‐ and cold‐walled circular channels

A finite difference analysis has been developed which predicts the temperature, pressure, and velocity distributions for the flow of thermoplastic materials in straight and tapered, hot and cold walled circular flow channels. This analysis when combined with the cavity filling analysis described in Part II, gives the molding engineer the capability of modeling the injection molding process from the shot to the cavity during injection. The information that is obtained from these analyses is useful in equipment design and modification since it allows numerical experiments to be performed so that one may ascertain the effects on moldability of flow channel and cavity geometry, material properties, and operating conditions. In addition, the information is useful in problem diagnosis and analysis to ascertain causes of and evaluate potential solutions to molding problems.