Investigation on induced-residual stress during end milling operation using analytical modelling

During end milling operation, the residual stresses are developed from two sources: plastic deformation of workpiece material and thermal energy generated. These two sources of residual stresses are often combined as one toward prediction of the efficient combined milling parameters which consequently minimised the residual stresses induced in the material. Hence, a mathematical model for predicting the magnitude of induced-residual stresses during end milling of 304L stainless steel was formulated, using analytical approach. The formulated model captured both mechanical and thermal (thermo-mechanical) stresses, which play a significant role during material deformation prior to fracture. The model was simulated with MATLABTM software. The mill cutter has a nose radius of 0.4 mm and operated at a constant cutting speed of 3 m/min. The simulation results showed that when the depth of cut was increased from 0.1 mm to 0.4 mm, the resultant residual stress varied from 150 MPa to 500 MPa, respectively. Evidently, the value of the residual stress value recorded same in both xx and zz-directions, at a particular depth of cut. However, the residual stress decreased exponentially as it approached zero under the surface of the material. Therefore, this model is capable of predicting the residual stresses induced during end milling operation, depending on the material (workpiece) properties, tooling material and selected end milling parameters.