Influence of turning parameters on distortion of bearing rings

The turning of bearing rings often leads to undesired form and dimensional changes after heat treatment which are referred to as distortion. In order to investigate the influence of cutting parameters on distortion, external longitudinal turning experiments were conducted. After machining the ring geometry and the residual stresses around the rings’ circumference were measured. The residual stresses were then released by a subsequent heat treatment. After the heat treatment the ring geometry was measured again. The results show that the residual stresses induced by the machining process correlate well with the dimensional changes after heat treatment. The cutting parameters that have the highest influence on the dimensional changes are the feed rate and the depth of cut. Residual stresses induced by soft-machining lead to an increase of the ring diameter, depending on the machining parameters.