Localized Flux Density Distribution Around a Hole in Non-Oriented Electrical Steels

A mechanical strain occurring during the drilling or punching of a hole on electrical sheets will cause deterioration of the magnetic characteristics around the hole. The result is that, when the sheet is magnetized parallel to the edge, the magnetic flux density has changed its orientation around the hole. In this paper, variation of localized flux density distribution around a hole was investigated from the search coils located at 0°, 25°, 45°, and 65° angles corresponding to the center of holes with diameters 10 and 20 mm in non-oriented electrical steel sheet with the dimensions of 300 mm length, 30 mm wide, and 0.50 mm thick standard sample. The localized peak flux density and magnetic field strength were measured over the peak flux density ranges 0.1-0.5 T at 50-400 Hz. A minimum peak flux density was obtained from the search coil, which is located at 65°, whereas maximum flux density was measured from the coil located at 0° angle.