Experimental evaluation of lubricant influence on residual stress in turning operations

In cutting operations it is very important to know the surface residual stresses on the final part since they affect functional aspects of the workpiece such as: fatigue life, resistance to corrosion and wear resistance. Recent studies showed that the development of tensile or compressive stresses is mainly influenced by the cutting parameters, tool geometry and the nature of the worked material. This paper reports the results obtained when studying the influence of different types of lubrication and of some process parameters (i.e. the tool nose radius and the feed rate) on the workpiece residual stresses in cutting operation. The experimental tests were carried out turning AISI 1045 steel bars. The maximum and minimum principal residual stresses on the surface were identified measuring the stresses along three different directions (0°/+60°/−60° with respect to the bar axis) using the X-ray diffraction technique. In addition, a 3D FEM model of the process was developed with the aim of proving the ability of such a model in predicting the surface residual stresses.