Hybrid modelling of sliding–sticking zones at the tool–chip interface under dry machining and tool wear analysis

Tool wear in machining processes strongly depends on the tool–chip interface. The sliding–sticking zones at this interface depend on the evolution of the local conditions of stress, velocity and temperature. Several authors have shown that because of the complexity of the tool–chip contact, the tribological conditions are not fully understood and accurate predictive models have yet to be developed. To propose a realistic model of chip formation, a hybrid analytical–numerical approach is presented in this work for the orthogonal cutting process. This simplified approach can be very useful for analysing the interaction between the chip formation process and the tribological conditions at the tool–chip interface. An analytical model is used to analyse the thermomechanical material flow in the primary shear zone, the tool–chip contact length, the local friction coefficient and the sliding–sticking zones. In addition, the temperature distribution in the chip is studied by numerical means. The effects of cutting conditions and material behaviour are evaluated. In the case of machining of Ti6Al4V titanium alloy, a quantitative comparison between model and experimental results is also provided to analyse the wear process.