Integration of IR based inline measurement systems of the surface temperature of square hollow profiles in an extrusion process

During the processing of plastics on single screw extruders, the melt temperature in the plasticizing unit and the product temperature at the die exit are important criteria of the product quality. This article aims to qualify an inline measurement system to determine the surface temperature of square hollow profiles in an extrusion process. An existing approach is developed by integrating another contactless system based on IR cameras into a device placed immediately after the die. The system is able to measure the temperature distribution of the profile surface. In addition, the melt temperature after the screw tip is measured and compared to the surface temperature after the die. The experimental investigations are carried out for two high density polyethylene and one polypropylene using different screw speeds and material specific temperature settings for a given three section screw. The experiments are carried out for stationary process conditions with simultaneously recording the melt and surface temperature. These target values are analyzed and compared to preliminary investigations based on IR pyrometers to qualify the investigated measurement system.