A new calibration tool and a new measuring system for calibrating infrared melt temperature sensors were put in operation. Operating instructions and supply maps for two different modes of operation were determined.
Measurements with 7 different polymers showed that calibration is not dependent on the type of polymer. Different absorption coefficients and the sample’s thickness does not affect calibration either. Due to the consideration of the sensor’s self-radiation the user specific calibration results in lower temperatures in comparison to the manufacturer’s calibration curve.
In the case of linear increasing or decreasing temperature profiles, displayed temperatures vary according to the amount of absorption. The more infrared energy passes through the polymer the bigger the discrepancies between temperaure readings and real temperature. When cooling the infrared melt temperature sensor with air-pressure to prevent incidental infrared energy from entering the transmission path not only the temperature probe will be cooled but also the surrounding tool and the polymer melt.