Magnetic Properties and Structure of Non-Oriented Electrical Steel Sheets after Different Shape Processing

Abstract

Non-oriented electrical steel sheets are the most often used materials in electrical rotary machines. Raw sheets must be formatted by various methods, e.g., punching, laser, spark or water stream cutting. Basic parameters of magnetic, electrical, and mechanical properties of the sheets are usually obtained from the producer, but namely magnetic properties are changed in dependence on additional machining processes. The aim of this study is to describe changes in magnetic properties after punching, laser or spark cutting of the original sheets M470-50A. The basic information about the structure of the cut edges of samples was obtained by optical microscopy and scanning electron microscopy. For the magnetic measurements toroidal samples were prepared by the mentioned technologies. The magnetic parameters were yielded from the measuring of magnetic hysteresis loops in dependence on saturation fields. The results are discussed from the point of view of applied cutting methods with the aim to obtain the best magnetic parameters and consequently determining the depth of the influenced material. After laser cutting, important decrease in remanence and increase in total losses were observed in comparison with the punched samples.

The Influence of Cutting Technology on Magnetic Properties of Non-Oriented Electrical Steel—Review State of the Art

“…In contrast, laser cutting does not induce any changes in the grain morphology near the cut line. Similar observations about punching and spark erosion can be found in [32,35,56,58,59]. Comparing the results of the above studies, it was found that punching "generates" plastic deformations much smaller than cutting with a guillotine.…”