A novel hybrid mold design to enhance thermal efficiency of injection molding process

Optimizing energy consumption in injection molding is crucial for process sustainability, particularly in thermal energy management. This study presents an innovative hybrid mold design conceived to address three main drivers: 1) reducing the mold thermal-conductive mass; 2) introducing thermal insulation of the mold core; 3) reducing the mold weight. This novel concept, characterized by an optimized design with polymer structural components, was benchmarked against a conventional steel mold through transient thermal analyses under various initial conditions. Experimental and numerical analyses using COMSOL Multiphysics were performed to evaluate the thermal behavior of the molds during successive injection cycles. The numerical model demonstrated good predictive capability, with temperature deviations below 5 °C when compared with experimental measurements under different operating conditions. The results demonstrated that the hybrid molds significantly improved heat retention within the steel insert, achieving up to 50% higher steady-state temperatures, thereby reducing energy demand to maintain the desired thermal conditions. Furthermore, the sharply reduced thermal-conductive core mass shortens the duration of thermal transients, achieving higher thermal mold sensitivity. The feasibility of the injection molding with the novel hybrid mold was demonstrated. The deviations measured in the sample dimensions are in the range of (−2, −6)%, thus consistent with the nominal material shrinkage and the different thermal regimes. The achieved average weight reduction on support plates is about 88%, resulting in lower mechanical energy requirements for the opening/closing steps in molding cycles and facilitating mold handling during product turnover operations.