Investigation of the influence of cobalt content and grain size of WC-Co cemented carbides on wear when shear cutting electric sheet metal

Abstract

In the production of electrical machines, shear cutting of electrical steel laminations before further processing into rotors and stators represents an essential manufacturing process. Investigations have shown that using abrasively worn active elements while shear cutting increases the hysteresis losses in the electrical steel sheet due to introduced deformations and resulting residual stresses. Therefore, knowledge of suitable tool materials is of great importance for producing high-quality electric motors. Due to its high silicon content, electrical steel has a strong abrasive effect on the tools, which is why Tungsten carbide cobalt (WC-Co) cemented carbides are commonly used. In this work, continuous stroke tests are carried out on an electric sheet with punches made of different WC-Co cemented carbides, differing in cobalt content and grain size. The punches are examined with increasing wear regarding cutting-edge geometry, surface condition and microstructure. The resulting cutting parts are inspected for cutting surface characteristics. In addition, the influence of geometry and tribology of the punches regarding residual stresses in the material is investigated by FEM-Simulation. The investigations will provide information on the wear development and causes when shear cutting electrical sheets and the effects on electric losses.