# Construction of a Cutting-Tool Wear Prediction Model through Ensemble Learning
## 1 Introduction
They also considered the negative strain rate and temperature effects of the material to modify the traditional empirical Johnson-Cook constitutive equation for SKD11 hardened steel. Based on the modified Johnson-Cook constitutive equation, they proposed a two-dimensional plane-strain finite-element model, coupled with thermal and mechanical loads for high-speed milling of SKD11. The FE model aims to simulate the geometric characteristics of chip formations during the high-speed milling processes and conduct the stress-and-strain quantitative analyses in the shear band. The cutting forces, cutting temperatures, and cutting performance of coated tools are also analyzed in the model. The results indicated that a critical value of cutting speed exists within a specific range. At this speed, stress and strain values increase, causing changes in stress and strain distributions in the shear band. This leads to the formation of a sawtooth chip. As the cutting speed continued to increase, the stress, strain, and temperature values in the shear band also increased, while the distribution in chip region remained unchanged, resulting in a more pronounced sawtooth chip pattern. The cutting forces decreased as the cutting speed increased, with temperature exerting a significant influence on cutting forces. The greater the temperature difference, the faster the decrease in cutting forces. [PERSON] et al. [12] used TiAIN- and TiSiN-coated carbide tools for the high-speed milling of hardened steel to determine the wear and breakage mechanisms of the cutting-tool. The effects of the tool angle, diameter, extended length, cutting forces, and cutting-induced vibrations on tool conditions were also investigated. The results showed that the primary patterns of tool wear observed included flank wear, rake face wear, breakage, and micro-chipping. The breakage modes were coating peeling, chipping, and tip breakage. Increasing the tool extended length led to increased cutting forces and tool wear, thereby decreasing surface quality. The abnormal states that occurred after tool wear could be detected through the signals of cutting forces and cutting-induced vibrations. The TiSiN-coated tools had a significantly longer tool life compared to the TiAIN-coated tools. Furthermore, experiments revealed that using cutting tools with a smaller rake angle, a smaller right clearance angle, and a large helix angle effectively reduced cutting forces, extended tool life, and facilitated smoother cutting processes. [PERSON] et al. [13] conducted milling experiments on H13 steel and SKD11 hardened steel by using coated carbide tools to investigate the tool wear and breakage mechanisms. The results indicated that the hardness of the workpiece had a dominant effect on tool failure patterns. In milling H13 steel, the tool failure pattern is flank wear, while in milling SKD11 hardened steel, tools were prone to breakage of the -take face due to the initiation and propagation of cracks. Furthermore, the geometry model of tool wear and breakage was established to explore the variations in cutting-tool angles resulting from the tool's wear or breakage mechanisms. Flank wear in H13 reduced the working clearance angle, while the breakage of the rake face in SKD11 reduced the working rake angle. Additionally, the effects of tool wear and breakage on cutting forces and chip formation were analyzed. In milling H13 steel, flank wear increased the friction coefficient between the tool and the workpiece, leading to increased cutting forces and the formation of wave-shaped chips. In contrast, in milling SKD11 hardened steel, the breakage of the rake face increases chip deformation and reduces the sharpness of the cutting edge, resulting in the curling and separation of sawtooth chips.