Prediction of surface residual stress after end milling based on cutting force and temperature

Abstract

Residual stress in the machined surface can significantly influence the performance of machined parts. In recent years many researches have been carried out to measure and predict the machining-induced residual stress, where the machining-induced residual stress is often regarded as the function of machining parameters. Yet it is the combined effect of the thermal and mechanical loads that directly affect the stress field during cutting process. In this research, the cutting forces and cutting temperature were measured during end milling process with different feed rate and depth of cut, and the surface residual stress along peripheral direction was measured after machining. The effect of thermal and mechanical loads on the formation process of residual stress was analyzed, and a new prediction model was proposed, which specifies the effect of thermal and mechanical loads, and which also takes into consideration the influence of feed rate and the depth of cut. Generally the thermal loads drive the surface stress to be more tensile, while the mechanical loads have the opposite effect. Larger feed rate weakens the effect of cutting forces on unit area of machined surface remarkably, while the influence of the depth of but is less significant. Under the cutting conditions in this research, the surface residual stress along peripheral direction is tensile, which indicates that the thermal effect plays the dominant role in forming residual stress. The coefficients in the proposed model were determined with experimental data, and the model was preliminarily verified. It might be a useful method to achieve a real-time prediction and control of machining-induced residual stress by monitoring cutting forces and temperature.