Experimental analysis of dishing deformation in multi-layer blanking of electrical steel sheets

Multilayered blanking is a novel innovation in the blanking process, allowing for an increase in productivity, particularly in the production of rotor and stator iron core sheets. This innovation increases the productivity of the process, but it leads to a decrease in the quality of the produced sheets when compared with sheets produced by conventional blanking. One of the available potential improvements in quality is the blanking of layers with different strength properties, specifically, the use of the same material but from opposite ends of the strength property range specified by manufacturer. This analysis explores impact of this innovation on dishing deformation of blanks, which greatly affects stacking factor of produced iron cores, by conducting a series of blanking operations on two layers of material, with each layer selected from material with different strength. After blanking, dishing deformation was observed on the produced samples and the results were compared. The setup where the material with higher tensile strength was positioned as top layer had deformation similar to configuration of two same materials. Configuration where material with higher tensile strength was positioned as bottom layer had greater deformation when compared to the previous two configurations. Based on these results, the use of layers with different strength properties does not appear to be an effective approach for reducing dishing deformation in multilayer blanking.