Estimation of Bulk Melt-Temperature from In-Mold Thermal Sensors for Injection Molding, Part A: Method

Abstract To improve part quality and consistency injection molders strive to control the temperature of the molten plastic during cavity filling. In-mold temperature sensors can effectively measure the temperature of the mold surface that contacts the melt; however, they do not provide a measure of the bulk melt temperature. An analysis was developed to use data from in-mold thermocouples to predict the plastic's bulk melt temperature. This analysis integrates the heat flux through the mold steel to calculate the bulk melt temperature. A mold instrumented with an in-mold thermocouple and an IR temperature sensor was used to validate the predictions. The effects of changing barrel temperature, coolant temperature, injection velocity, and cooling time were studied using a 21 run DOE. Validation was performed by comparing bulk temperature data from the IR temperature sensor with temperature predictions derived from the in-mold temperature sensor. Trends in the melt temperature were consistently predicted, ho...