## 1 Introduction
Milling experiments were conducted using PVD-AlSiTiN-coated tungsten carbide tools of different diameters, analyzing the effects of tool diameter, cutting speed, feed rate, and depth of cut on several response parameters, including cutting force, cutting torque, material removal rate, tool wear, and surface morphology. The results indicated that by increasing tool diameter and cutting speed, the surface roughness may be effectively reduced, while different HEA compositions had varying effects on machining responses. An increase in tool diameter led to a rise in chip thickness, significantly affecting the feed force and radial force. Among the tested HEA samples, Cr\({}_{20}\)Mn\({}_{10}\)Fe\({}_{20}\)Co\({}_{30}\)Ni\({}_{20}\) exhibited the best performance in terms of average surface roughness. Further experiments revealed that the interactions between cutting speed, axial depth, and feed rate played a crucial role in machining. The second-level cutting speed and depth of cut, combined with the third-level feed rate, were identified as the optimal conditions. Microstructural changes contributed to the formation of surface defects, which could be mitigated by employing low feed rates and high cutting speeds. Ultimately, the surface roughness of the HEA samples improved after machining, with CrMnFeCoNi showing a 1.547% increase in microhardness. [PERSON] et al. [13] investigated the mechanical properties, tribological properties, and corrosion resistance of AlCrNbSiTi HEA nitride coatings with different nitrogen flow rates. They further applied these coatings in the milling of the nickel-based alloy Inconel 718. Using reactive RF magnetron sputtering, HEA nitride coatings were deposited on tungsten carbide tools within a nitrogen flow range of 0-20 cm\({}^{3}\)/min. Various measurement instruments were used to analyze the coatings' chemical composition, chemical bonding characteristics, and crystalline structure. Additionally, the hardness, elastic modulus, adhesion strength, friction coefficient, and wear resistance of the coatings were evaluated. Corrosion resistance was assessed through potential polarization testing. Finally, face milling experiments on Inconel 718 were conducted using milling to analyze the effect of the coatings on tool life. The results indicated that all coatings exhibited an amorphous structure. As nitrogen flow was increased, coating hardness also increased, reaching its highest value at a nitrogen flow of 15 cm\({}^{3}\)/min. Under these conditions, the coating demonstrated the best wear resistance, the lowest friction coefficient, and excellent corrosion resistance. Further milling experiments revealed that tool wear may be effectively reduced during the machining of Inconel 718 when the coating with a nitrogen flow of 15 cm\({}^{3}\)/min. After a milling distance of 18 m, the tool wear depth was only 154.4 \(\upmu\)m, showing significant improvement compared to uncoated tools and tools coated without nitrogen. [PERSON] et al. [14] investigated the manufacturing quality of CrMnFeCoNi HEA produced using laser powder bed fusion and further applied it to milling experiments. They explored the effects of process parameters on cutting force, surface roughness, and tool wear. Using uncoated tungsten carbide tools, a milling experiment was performed on the HEA while varying process parameters such as feed rate, cutting speed, and depth of cut to analyze their influence on cutting force, surface roughness, and tool wear. A comparative analysis with 304 stainless steel was also conducted. The results showed that the HEA exhibited good homogeneity and machinability. Compared to 304 stainless steel, the HEA required lower cutting forces, experienced less tool wear, and achieved better surface roughness. Additionally, the cutting force of the HEA was increased with increasing depth of cut and feed rate, while the most stable performance was observed at the lowest cutting speed. Tool wear did not show significant variation, and surface roughness was reduced by 61.3% compared to 304 stainless steel.