Barrel Temperature: Key temperatures requiring control during the injection molding process include barrel temperature, nozzle temperature, and mold temperature. The first two primarily affect plasticization and flow, while the mold temperature mainly influences flow and cooling. Each type of plastic has a distinct flow temperature; even within the same type of plastic, flow and decomposition temperatures can vary based on source or grade-differences attributable to variations in average molecular weight and molecular weight distribution. Furthermore, the plasticization process varies depending on the type of injection molding machine used, necessitating different barrel temperature settings.
Nozzle Temperature: Nozzle temperature is typically set slightly lower than the maximum barrel temperature to prevent "drooling" (uncontrolled leakage of molten material) in open-type nozzles. However, the temperature must not be too low; otherwise, premature solidification of the melt could clog the nozzle, or solidified material injected into the mold cavity could compromise the product's properties.
Mold Temperature: Mold temperature significantly impacts both the internal properties and the surface quality of the finished product. The appropriate mold temperature is determined by factors such as the plastic's crystallinity, the product's dimensions and structure, performance requirements, and other processing parameters (including melt temperature, injection speed and pressure, and the molding cycle).
