Novel Types of Thermocouple for Plastics Processing.

It is an established fact that on all injection molding machines and extruders there are differences between the temperatures set on the temperature controllers and the melt temperatures within the processing cylinder (up to 100 degree C in extreme cases). In the reported program, a range of conventional thermocouples of differing design were investigated for their operating behavior. The results were compared with those obtained with a newly developed thermocouple design. The data determined with the new thermocouples on the test cylinder were confirmed by practical trails on injection molding machines and extruders from different manufacturers. The new thermocouples are found to give considerably greater agreement between the controller temperatures set and the actual melt temperature than conventional thermocuples.