Numerical modelling of residual stresses during orthogonal cutting of Ti6Al4V using internally cooled cutting inserts

Abstract

Residual stress has an adverse effect on the fatigue strength of machined components. The parts used in high end industries like aerospace and automobile sector needs to be carefully examined for the residual stress development during machining process. In this paper, both thermal and mechanical effects have been taken into account to predict the residual stress in workpiece while machining using internal cooled cutting inserts. The internal cooling system has now a days being used as an advanced cooling system for Ti and Ni based materials. In the present paper, Oxley’s model for slip line theory and contact theory using McDowell’s hybrid method have been used to predict the forces and residual stress respectively. The effect of change in the flow of lubricant from laminar to turbulent in internal channel of cutting insert has also been analysed. It has been found analytically that the cutting force of 761 N during dry turning is decreased to 511 N and 494 N in case of laminar and turbulent flow respectively. Besides this, the generation of compressive residual stress is found at the surface layer of machined specimen for internally cooled cutting inserts. The maximum compressive stress of 150 MPa at 0.03 mm depth of work piece has been found in case of laminar flow and 100 MPa for the turbulent flow.