Plastic intensity reduction using thermally insulating coatings for injection molds

The use of plastics in today's world is still increasing despite its enormous burden for environmental sustainability. The urge to reduce plastics impact is driving the development of novel technological solutions. The high viscosity of thermoplastic polymer melts often leads to the design of oversized plastic parts having wall thickness higher than structural requirements. This work proposes a novel approach to wall thickness reduction, exploiting the thermally insulating effect of mold coatings. Four different mold coatings were characterized using inline rheological testing carried out on a PET using a slit-die open mold. The thermal boundary condition of a numerical model was calibrated by fitting the numerical to experimental pressure values. The thickness reduction associated with the use of a specific coating was then quantified for a case study geometry using the calibrated model. The results indicated that it is possible to reduce the thickness of the part by 12%, leading to material consumption and cycle time reduction of 8% and 22%, respectively.