Cutting Force and Surface Roughness Characterization in Cryogenic High-Speed End Milling of Ti-6Al-4V ELI

This study investigates the cutting forces induced during high-speed end milling of titanium alloy (Ti-6Al-4V ELI) as well as the surface quality of the milled surfaces. The high-speed machining was performed using carbide tool of coated and uncoated types at three cutting speeds of 200, 250, and 300 mm/min and two feed rates of 0.03 and 0.06 mm/tooth. Surface integrity was characterized in terms of surface roughness (Ra) and morphology. Cutting speed was found to be inversely proportional to the resultant cutting force at any cutting conditions. Cutting force in the X direction displayed higher sensitivity against cutting conditions. The results showed that feed rate is proportional to cutting force in X and Y directions regardless of tool type. Under the fixed feed rate condition, cutting force decreased at higher cutting speed for both tools. It was also found that uncoated tool induces less cutting force compared to coated one. High-speed end milling using uncoated tool provided better surface finish than using a coated carbide tool, especially at lower cutting conditions. However when coated carbide tool was used, surface roughness improved significantly with the increase in cutting speed. In contrast, almost opposite phenomenon was observed when uncoated tool was used.