Determination of the hardening depth by using inversely determined micro-magnetic characteristics

Abstract

Abstract To find a quick method to quantify the depth of hardening in order to optimize the production process at thyssenkrupp Presta Schönebeck GmbH, micromagnetic characterization after surface heating is used. The difference between the following method and other proceedings is that the depth is measured on the opposite surface of the heated side. For this research process the “MikroMach“-system is used, which contains the four analyzing methods: eddy current, Barkhausen-noises, harmonic content and superposed permeability. The results of reference measurements are evaluated by statistical methods, thereby defining the parameters which manifest a high correlation and a low variation towards hardening depth. Based on these characteristic variables, the MikroMach software starts a multiparameter analysis to find a polynomial. As a result of this, a reference is given which is used to classify the components into functioning or defective goods. After that, the system was tested in the production area to validate the characteristic polynomial. As a result of these tests, it is shown that the classification of components is possible. In addition to that, the system showed unexpected influences of divergent heating parameters. But there are differences between the conventional depth of hardening and the quantitative measuring by using micromagnetic characterizations. The differences are caused by the quality and numbers of references in calculating the polynomial.