High cutting temperatures increase tool wear and reduce tool life. To achieve a longer tool life, coated carbide tools have been developed. In this study, the influence of tool coatings on the cutting temperature distribution during the orthogonal cutting of H13-hardened steel is investigated. Firstly, four coating materials, including TiC, TiN, Al₂O₃, and TiAlN, with the same coating thickness, are selected to evaluate the effects of coating materials on cutting temperature with finite element simulation. The maximum temperatures at the tool rake face and the temperatures at the coating–substrate interface are evaluated. It was found that the maximum temperatures at the tool rake face were the lowest and the highest when TiN and Al₂O₃ coating materials were applied, respectively. The TiAlN coating material had the best thermal barrier property. Then, the temperature distribution along the direction perpendicular to the tool rake face is investigated for TiAlN-coated tools with different coating thicknesses ranging from 3 μm to 10 μm. It is shown that the temperature gradient increases with the coating thickness. The coating thickness should be kept below 5 μm. Finally, cutting experiments validate the availability of the finite element model.

This study designs a differential dual-drive micro-feed mechanism, superposing the two “macro feed motions” (“motor drive screw” and “motor drive nut”) using the same transmission of “the nut rotary ball screw pair” structure. These two motions are almost equal in terms of speed and turning direction, thus the “micro feed” can be obtained. (1) Background: Thermal deformation is the primary factor that can restrict the high-precision micro-feed mechanism and the distribution of heat sources differs from that of the conventional screw single-drive system owing to the structure and motion features of the transmission components. (2) Discussion: This study explores the thermal field distribution and thermal deformation of the differentially driven micro-feed mechanism when two driving motors are combined at different speeds. (3) Methods: Based on the theory of heat transfer, the differential dual-drive system can be used as the research object. The thermal equilibrium equations of the micro-feed transmission system are established using the thermal resistance network method, and a thermal field distribution model is obtained. (4) Results: Combined with the mechanism of thermal deformation theory, the established thermal field model is used to predict the axial thermal deformation of the differential dual-drive ball screw. (5) Conclusions: Under the dual-drive condition, the steady-state thermal error of the nut-rotating ball screw transmission mechanism increases with the increase in nut speed and composite speed and is greater than the steady-state thermal error under the single screw drive condition. After reaching the thermal steady state, the measured thermal elongation at the end of the screw in the experiment is approximately 10.5 μm and the simulation result is 11.98 μm. The experimental measurement result demonstrates the accuracy of the theoretical analysis model for thermal error at the end of the screw.

In this study, a three-dimensional thermo-mechanical coupled finite element framework for orthogonal cutting with coated tools was established in ABAQUS/Explicit. The framework incorporated the Johnson-Cook constitutive model and a temperature-dependent modified Coulomb friction model. The transient mechanical and thermal responses of uncoated WC-Co, TiN-coated, and TiAlN-coated tools were evaluated at cutting speeds of 50, 100, and 150 m/min. Long-term wear evolution was then predicted by integrating the Usui wear equation with three-stage nonlinear wear theory. Prediction errors for cutting force and cutting temperature remained within 10% across the tested cutting speeds. The TiAlN coating reduced friction and restricted heat conduction into the tool substrate under high strain-rate conditions. The near-field tool temperature decreased by 4.0% to 9.5%, with an 8.2% reduction at 150 m/min. Compared with uncoated WC-Co, TiAlN reduced the simulated main cutting force by 6.0%, 5.6%, and 4.4% at 50, 100, and 150 m/min, respectively. Cutting experiments yielded force reductions of 5.0% to 7.1%. After 30 min of dry cutting at 150 m/min, the model predicted flank wear depths of 0.398 mm for uncoated WC-Co, 0.261 mm for TiN, and 0.235 mm for TiAlN. Relative errors against the measured flank wear depths ranged from 3.4% to 4.7%. The small error between the predicted wear evolution and the experimental data demonstrated that the established model achieved a high level of predictive accuracy.