Stress cracking in the case of the hot-plate welding of moulded parts made of amorphous thermoplastics

摘要

Investigations were conducted into the stress cracking in the case of the hot-plate welding of amorphous thermoplastics — especially of motor-vehicle tail lights. Wetting tests, photoelastic investigations and measurements of the internal-stress condition using strain gauges according to the drilled-hole method took place for this purpose. The hot-plate welding process was then simulated using the finite-element method. It was shown that the susceptibility to stress cracking can be minimised by reducing the hot-plate temperature and the heating duration, by avoiding ribs and notches as a result of design-related measures as well as by means of preheating or of the further processing of moulded parts which are still warm from the injection-moulding process.