Modeling the Effects of Minimum Quantity Lubrication on Machining Force, Temperature, and Residual Stress

Residual stress is one of the critical characteristics for assessing the qualities and functionalities of machined products in light of its direct effect on endurance limit, distortion, and corrosion resistance. Primary factors responsible for residual stresses distribution include mechanical effects, thermal effects, microstructure evolutions, and a combination of these mechanisms. This study investigates the effects of minimum quantity lubrication (MQL) on machining force, temperature and residual stress through a physics-based modeling method. Both the lubrication and cooling effects caused by MQL air-oil mixture contribute to changes in friction due to boundary lubrication as well as variations in the thermal stress due to heat loss. The modified Oxley's model is employed to predict the cutting force and temperature directly from cutting conditions. The predicted cutting force and temperature are then coupled into a thermal-mechanical model which incorporates the kinematic hardening and strain compatibility to predict the machining-induced residual stress under lubricated conditions. The proposed analytical method is experimentally verified by orthogonal cutting tests for AISI 4130 alloy steel in the context of forces, temperatures, and residual stresses.