The melt temperatures for Desmopan® and Texin™ extrusion range from 160 to 230 °C and depend on the product type, its Shore hardness and its melt range.
The size of the extruder and the screw diameter also affect the temperature setting. The peripheral velocity of the screw should not exceed 0.3 m/s. If larger extruders are used, lower temperatures may generally be set on account of the higher shear strain. Fig. 1 specifies guideline temperature settings for the cylinders and mold heaters.
Fig. 1: Temperature profile according to hardness range
In certain circumstances, it may be advantageous to use an “inverse temperature profile”. When this is the case, the peak temperature is located in the feed zone.
By adjusting the nozzle temperatures, it is possible to control the glossiness of the article’s surface. Low temperatures result in matte surfaces and high temperatures in glossy surfaces.