Die Wear Severity Diagram and Simulation

Die wear is a significant issue in sheet metal forming particularly for stamping Advanced High-Strength Steels (AHSS) because of their higher strength and microstructure composition. Reliable predictions of the magnitude and distribution of die wear are essential if cost-effective wear-protection strategies are desired in the early stages of tooling development. A die Wear Severity Index (WSI) is introduced in this paper to quantify the magnitude of die wear, which in essence characterizes the frictional energy dissipation per unit area on the die surface throughout the entire forming cycle. It can be readily obtained as part of any finite element simulation of stamping process utilizing incremental solution techniques. A two-dimensional example is investigated in great detail to illustrate the applicability of the concept, where three grades of steels (a DP600 AHSS steel, a HSLA350 conventional HSS steel, and a DQAK mild steel) are simulated and wear performance are obtained and compared. The concept of Die Wear Severity Diagram (DWSD) is then presented for three-dimensional production dies where the Wear Severity Index is color-mapped on the die surface. It enables tooling engineers to identify critical areas needed for most appropriate wear-enhancement actions based on their wear severity. The practical application of the concept and methodology is demonstrated by a production example of the Die Wear Severity Diagram for a Tailored-Welded-Blank (TWB) B-pillar with 1.65mm DP600 and 0.90mm DDQ steels.