Standardisation concept for rapid testing of effects of cutting on losses of electric steel and amorphous ribbon

Abstract

Soft magnetic lamination is produced with high width that usually is reduced by cutting. It yields permeability decreases Ɵ and loss increases r. So far, existing corresponding data is not consistent, since derived from strongly different lamination widths W. A consistent, ultra-rapid test method is suggested, for international standardisation. It is based on a multi-frequency single sheet tester. A 50 cm long, precisely prepared material sample of W = 17 cm is inserted into it, for an initial measurement in non-cut state. Then, it is cut into two 8.5 cm wide strips, for a test in cut state. Changes Ɵ and r are evaluated for induction values B up to 1.8 T. They are rapidly measured for frequencies of 50, 400 and 1000 Hz. Results from steel are described for guillotine cutting, from amorphous ribbon also for scissors. As a general tendency, Ɵ exceeds r by an order of about 3, however, with low reproducibility. Thus, standardisation is suggested for loss-rise functions r(B) only. Examples of r-functions reveal strong individual differences, as foot-prints of different products. With increasing f, r-values tend to sink. With increasing B, they rise, except for high B of NO steel. Amorphous ribbon shows non-clarified deviating tendencies. Standardisation of r-tests promises comparable information on cutting effects, for a given material, through a given cutting tool—but also on the tool's state of wear.