Mathematical and experimental determination of temperature, velocity, and pressure fields in flat molds during the filling process in injection molding of thermoplastics

When injection molding thermoplastics, temperature, velocity and pressure distribution not only vary markedly over the mold cross‐section, but also along the flow path. Moreover, these parameters also vary with time. Using the example of a typical injection‐molding material‐high impact polystyrene—the distributions in the flat mold are calculated and discussed. It was possible to test calculations by means of comparative experimental tests in an injection molding unit with variable wall thicknesses and long flow paths. The purpose of these investigations is to give a better physical understanding of these complicated flow processes and to provide indications for optimum process control.