A numerical-analytical approach to predict white and dark layer thickness of hard machining

Modeling of phase transformations induced by hard machining is a major interest for researchers due to their critical impact on surface integrity. These transformations are commonly referred to as white layers (WLs) and/or dark layers (DLs). This paper presents a new approach to predict the formation of WLs and DLs in orthogonal cutting of AISI 52100 hardened steel. A numerical–analytical method is developed based on three principal steps: (i) development of a 2D finite element model (FEM) of a hard turning operation, (ii) prediction of the temperature, the equivalent stress, and the strain energy in the machined surface, and (iii) analytical calculation of the transformation temperature and prediction of the WL and DL thickness. The predicted results of cutting forces, chip morphologies, WL thickness, and DL thickness are physically consistent with previous experimental works. The developed model is further used in order to investigate the effect of cutting speed, feed rate, and tool flank wear on the depth of the generated layers. This proposed approach can be used to optimize cutting process parameters to minimize layer thickness.