Application of the drag force method to evaluate magnetic property degradation near the cut edges of electrical steels

Abstract

The increase in hysteresis loss associated with the altered microstructure and residual stress fields in regions near the cut edges of electrical steels is investigated by means of drag force measurements. Measurements are made using relatively narrow magnets on samples of two grades of nonoriented steels cut by laser or mechanical processes. Largest drag forces, hence losses, are consistently found in slow laser cut samples, smallest drag forces with fast laser cut samples, and moderately higher losses in mechanically cut samples. These results are consistent with other measurement methods.

Quantifying Effects of Cutting and Welding on Magnetic Properties of Electrical Steels

“…9 and 10 illustrate the degradations on losses and relative permeability of M400-50A, for a strip width of 10 mm, after cutting with the settings that result in the best and the worst magnetic properties. The laser setting with the highest power and the highest speed, out of the tested settings, results in the best magnetic characteristics, which is in line with results in [14]. Due to the high speed, the productivity of the cutting tool can increase while keeping the magnetic degradation in the lowest possible level (lowest among the tested settings).…”

“…In [13], Epstein and stator stack measurements conducted on SiFe laminations indicate that solid-state laser cutting and CO2 laser cutting cause similar increase in the specific losses. In [14], the lowest iron losses are seen in test samples manufactured using fast laser cutting. Furthermore, cutting is found to affect hysteresis losses more than eddy-current losses [15]- [17].…”

“…The idea of using a degradation zone from the cut edge of an electrical steel sample for improving loss modeling and calculation tools is presented in [12], [14], [15], and [19]- [22]. The analysis of the measurements differs based on the usage of the extracted data in the design tools.…”

“…Three approaches may be separated among the selected set of references. The first approach is to determine equivalent material characteristics assuming the sample width is uniformly damaged (easy to implement in FEM models but not physically accurate) [12], [14], [15], [19]. The second approach is based on identification of the width of the damaged area and its material properties, defining thin regions along the cut edges in the FEM geometry with different magnetic properties [20], [21].…”

Characterizing local anisotropy of coercive force in motor laminations with the moving magnet hysteresis comparator

“…The field intensity for such a PM has been shown 9 to be greatest at its center, notably smaller at its edges, and diminish ever more rapidly with increasing transverse distance from its edges. These features are quantitatively dependent on the PM size and shape.…”