Comparative Performance Analysis of Coated Carbide Insert in Turning of Ti-6Al-4V ELI Grade Alloy under Dry, Minimum Quantity Lubrication and Spray Impingement Cooling Environments

In metal machining, a large amount of heat is generated which significantly affects the machining performance, and therefore, a suitable cooling/lubricating strategy is required to control this heat. The consumption of applied coolant is a hazard for biological and ecological concerns. However, this work implemented three distinct cutting environments (dry, MQL (minimum quantity lubrication) and SIC (spray impingement cooling)) to study the tool wear, surface roughness, surface topology, cutting temperature and chip morphology in turning of Ti-6Al-4V ELI alloy. SIC is one of the new cooling strategies in which atomized water spray impinges into the cutting region with the help of compressed air. Ti-6Al-4V ELI alloy machining is difficult due to its poor thermal conductivity, highly reactive at elevated temperature, etc. Considering the machinability results, MQL exhibited the lower flank wear and surface roughness over dry and SIC cutting conditions, while very low temperatures were obtained under SIC compared to dry and MQL cooling conditions. Abrasion, notch wear, adhesion and diffusion mechanisms are the primary mode of wear identified. The tool life under dry, MQL and SIC cooling conditions is estimated as 540 seconds, 1500 seconds and 995 seconds, respectively; however, MQL cooling-assisted turning exhibited 177.77% larger tool life relative to dry cutting and 50.75% longer tool life compared to SIC turning; thus, MQL optimal condition (ap = 0.2 mm, f = 0.12 mm/rev, v = 79 m/min) is recommended to utilize for turning of Ti-6Al-4V ELI alloy for industrial applications.