Experimental investigation of cutting force, surface roughness and tool wear in high-speed dry milling of AISI 4340 steel

The high-speed dry milling of AISI 4340 steel was carried out with a CVD Al₂O₃/TiCN coated carbide tool. The relationships between cutting force, surface roughness and cutting parameter were conducted, and the influence of tool wear on cutting force and surface roughness was also investigated. The wear mechanism of coated tool was revealed by SEM micrograph and EDS analysis. Due to the lower tool wear rate, the increase of cutting forces and surface roughness R_a was smaller at the initial wear stage and the steady wear stage, whereas the increase of cutting forces was improved suddenly when the flank wear was more than 0.25 mm. Additionally, the coated tool wear was mainly caused by adhesion, abrasion, oxidation and diffusion, accompanied with a little peeling and chipping. The research results are expected to provide optimum cutting parameters for high-efficiency machining of high-strength steel.