Prediction of coated tools performance in milling based on the film fatigue at different strain rates

The knowledge of coated tool wear mechanisms in milling is pivotal for explaining the film failure and selecting the appropriate cutting strategy and conditions. In this paper, tool wear experiments were carried out in milling of four different steels using coated cemented carbide inserts. The variable stress, strain and strain rate fields developed in the tool during cutting affect the film-substrate deformations and in this way the resulting coatings loads and its fatigue failure. For investigating the influence of cyclic impact loads magnitude and duration on the films' fatigue of coated specimens, an impact tester was employed which facilitates the modulation of the force signal. The attained tool life up to the films' fatigue failure was associated to a critical force for the film fatigue endurance and to the cutting edge entry impact duration. These factors converge sufficiently to the tool life in all examined milling kinematics and workpiece material cases.