In-situ temperature measurements in the depths of injection molded parts

Abstract

Injection molding has been the most widely used polymer processing method for manufacturing plastic parts. In the process, the temperature is an important parameter that influences process features such as cycle times, crystallization rates, degree of crystallinity, melt flow properties and molded product qualities. This report proposed a special experimental set-up, which includes an injection mold equipped with tubular needles for guiding embedded thermocouples, to measure the temperature field inside the cavity. It was found that the disturbance induced by the probes remained negligible and precise temperature profiles could be measured at various positions inside the cavity. Viscous dissipation of the polymeric materials in the runners resulted in a significant increase of melt temperature. Additionally, a transient heat transfer finite element model was proposed to simulate and predict the temperature variation in injection molded products. It was shown that the numerical prediction coincided satisfactorily with the measured temperature data.