Influence of hole size and cutting method on localised flux density distribution around a hole in non-oriented electrical steels

Abstract

In the manufacturing of electrical machine cores, there exist various cutting processes for electrical steel laminations such as mechanical, laser, and abrasive waterjet. The microstructure of the material changes near the edge affecting the magnetic domain structure and domain wall motion during the magnetization process. Variation of localised flux density distribution due to cutting method and hole size was investigated using the search coils located at 0(ay), 25(ay), 45(ay), and 65(ay) angles corresponding to the centre of holes with diameters 10 and 20 mm in non-oriented electrical steel sheet, which was namely N530. The localised flux density was measured over the peak flux density ranges 0.1-0.5 T at 50-400 Hz. The localised linear flux density concentrated on around both holes was obtained with increasing frequency. Also, cutting method was significant to deteriorate magnetic properties at the small cross sectional areas under the search coils located. The smaller hole has less to effect on the flux orientation around than the larger hole, due to their magnetostatic energy.