Grinding of ferrites, some mechanical and magnetic aspects

A review is given of grinding, the resulting mechanical deformation and the effects on the magnetism of ferrites. The grinding system is divided into components and the laws of material removal are stated with particular emphasis on the role of the forces in the system. From the geometry of horizontal spindle grinding a useful parameter is derived, the continuum chip thickness, that can be used for comparing grinding situations. Under these forces the abrasive particles deform and remove the surface. The various modes of deformation of the material are considered. Due to tensile stresses a brittle mode is found. Moreover, underneath the abrasive particle high compression occurs that allows ductile deformation. The latter mode requires more energy per unit volume of material removed. Deformations occur underneath the abrasive particle, but also in front of it, caused by the impact sound wave, and behind it where the compression has changed into tension. Finally the influence of deformation on magnetization, on permeability, losses and domain patterns is considered.