Investigation of thermal contact resistance in injection molding using a hollow waveguide pyrometer and a two-thermocouple probe

This Note describes an apparatus that characterizes the nature of thermal contact between polymer and mold through the different phases of a typical injection molding cycle. The key idea is the combination of the measurements provided by a hollow waveguide pyrometer and a two-thermocouple probe to determine the thermal contact resistance (TCR). The hollow waveguide pyrometer is used for the on-line monitoring of the temperature at the surface of the polymer stream, while the two-thermocouple probe is utilized to determine via an inverse heat conduction procedure the heat flux crossing the polymer-mold interface and the temperature at the cavity surface. The experimental results show that TCR between polymer and mold is not negligible and not constant with time. (C) 2003 American Institute of Physics.