Dr. Markus Schneider on Euro PM2019: Weld Lines And Its Effect On The Fatigue Response Of Case-Hardened MIM 8620 Steel

Sintered MIM steels exhibit the highest possible density for enhanced applications. One concern is about the effect of weld lines on the fatigue response if they occur in highly-loaded part regions. Weld lines occur during the metal injection molding process of complex-shaped parts when two or more feedstock fill fronts meet each other and weld together. Due to their optical visibility their effect on the mechanical properties should be discussed. A new tooling, cavity, and gate concept allow the shifting of the weld line to any position to simulate a twin-gated molding process. Fatigue bending bars made of MIM 8620 steel with different gates were molded, debinded, sintered, and case-hardened. It could be shown that there is a drop of the fatigue strength at the knee point if the weld line is located in the highly-loaded part region and the weld line is loaded with fracture opening mode 1.

Session 7

MIM Simulation and Process Control

Monday, 14.10.2019