FEM and experimental analysis to study the effect of tool wear on the surface integrity of finish hard turned EN31 steel

Tensile residual stresses along with the brittle white layer, produced on the work piece, limits the use of hard turning process at the shop floor. In this work, the effect of tool flank wear on the residual stresses has been studied along with correlation of the residual stresses with the white layer developed during hard turning of EN31 steel using a CBN insert when machining with a tool having predefined flank wear. FEM based machining model was developed to predict the residual stress in the subsurface region. Effect of flank wear on the residual stresses induced in the machined work piece subsurface region was analyzed. Stress profiles became less compressive (or more tensile) with increase in the cutting speed as well as with higher flank wear. The correlation analysis showed a high degree of correlation of the residual stresses with tool wear and white layer thickness observed experimentally.