Topographic characterization of progressive wear on deep drawing dies

The subject of this paper is an analysis of progressive wear and other surface alteration processes which take place on deep drawing dies. The deep drawing process was simulated using strip test evaluation equipment. A theory on the influence of different surface alterations on the die topography was then developed. The wear progress was quantified using conventional surface roughness parameters as well as a set of recently developed parameters based on the bearing curve and extended to three dimensions. It was concluded from conventional surface roughness measurements that maximum wear takes place at angles of 20 degrees and 70 degrees from the vertical direction on the die. Furthermore, it was observed from three-dimensional measurements that the progressive wear is initiated by ploughing after only a few drawings and this mechanism continues until the die is worn out. In the investigations described in this work, the wear progress was interpreted using the three-dimensional parameters S-pk and S-vk in terms of an initial ploughing stage followed by a second stage during which ploughing and abrasive wear occur simultaneously.