For wear testing short-time methods like the so-called platelet-wear-test are widely used, allowing for accelerated wear measurements on plastic mold steels under intensified injection molding conditions.
In our study wear of a through hardened powder metallurgical mold steel was measured as progressive material loss of two wear specimens on their surface over injecting 50 kg polyamide 66 melt reinforced with 50 wt% glass fibers.
We detected experimentally a clear dependence of wear on the measured volumetric flow rate. A tremendous effect of such intensified wear conditions was high viscous dissipation which led to very high temperatures on the surface of the wear specimens. As a result a distinct decrease in steel hardness at the surface was detected. The measured hardness profile and its extension in depth indicated strong influence of the temperature field in the wear gap. The experimental results were validated by a 3D-simulation of the non-isothermal melt flow in the wear slit. In the boundary layer a melt temperature of approx. 700 °C and a steel surface temperature of approx. 465°C was calculated after just one injection cycle. These results confirm the assumption of high viscous dissipation.