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Abstract: The knowledge of coated tool wear mechanisms in milling is crucial for explaining film failure and adjusting appropriately the cutting conditions. In the described research, coated cemented carbide inserts were applied in up- and down-milling stainless steel for monitoring the tool wear at repetitive cutting loads of various magnitudes and durations. The variable stress, strain and strain-rate fields developed in the tool during milling affect the film-substrate deformations, and thus the resulting cutting loads and the coating fatigue failure. For investigating the influence of cyclic impact load magnitude and duration on the film fatigue of coated specimens, an impact tester was employed which facilitates the modulation of the force signal. Using this device, repetitive impact loads with different duration and time profiles were applied on coated cutting inserts. These loads approximately simulate the developed ones in milling when the cutting edge penetrates the workpiece material. The attained coated tool life was associated with the developed maximum strain and its rate in the film during milling. The latter factors were correlated to the strain and strain rate dependent on coating fatigue endurance. In this way, the tool life in all examined milling kinematics and chip geometries was sufficiently explained. [Copyright &y& Elsevier]

Abstract: The coated tool wear evolution in milling at constant cutting conditions can be described analytically based among other factors on the cutting edge entry impact duration. A tool wear predictive mathematical model for milling parts of complicated geometry was created employing this methodology and a commercial CAM system. Parameters of the developed model were determined based on experimental results. In this way, the expected tool wear growth during numerically controlled milling can be estimated, considering the cutting penetrations along the tool paths, the process up or down kinematic and other factors. The application of the introduced model is demonstrated through appropriate examples. [Copyright &y& Elsevier]

Abstract: The wear behaviour of PM-HSS milling inserts is investigated experimentally. Cutting inserts with different cutting edge radii tested in industrial conditions were examined. The radii have been obtained either by micro-sandblasting or by honing. The initiation and progress of the tool wear was analysed with scanning electron microscopy (SEM) of the cutting edges. The experimental results exhibit quantitatively the effect of tool radius on the performance of milling inserts. A radius on the cutting edge prevents fast and unpredictable wear. Moreover, the existence of an optimum value of the radius has been revealed experimentally. In parallel, 2D finite element cutting simulations based on Lagrangian thermo-viscoplastic formulation are used to analyse the tool-stress distributions within the tool coating and substrate. The results obtained from this study provide a fundamental understanding of the cutting mechanics for the coated tool used and can assist in the optimisation of tool edge design. Particularly, the results obtained from the simulations have confirmed that there exists an optimum cutting edge radius that minimizes tool stresses, especially within the coating layer, which seems to be a key factor in the case of milling in dry high speed conditions. [Copyright &y& Elsevier]