Enhancing Tool Life and Surface Quality in High-Speed Milling of Ti6Al4V: A Comparative Study of Flood and Minimum Quantity Lubrication Cooling Strategies

Ti6Al4V has excellent strength and corrosion resistance for use in the automotive, aerospace, and biomedical industries, but its poor thermal conductivity and built-up edges forming lead to significant tool wear and machining challenges. To improve heat dissipation and machining performance of Ti6Al4V during high-speed milling, this study aims to investigate the effects of cooling strategies and milling parameters on cutting force, tool wear, and surface roughness. Research was conducted at spindle speeds of 1194, 1791, and 2389 r/min and feed rates of 358, 538, and 717 mm/min, using uncoated carbide tools, with flood and minimum quantity lubrication (MQL) cooling methods. Results indicate that the MQL cooling strategy led to lower surface roughness, cutting forces, and tool wear compared to flood cooling method. At 1194 r/min spindle speed, the MQL method achieved a maximum improvement in surface roughness of 15.33% at 358 mm/min and tool wear of 83.16% at 738 mm/min over flood cooling. The optimal milling settings for 26.7 µm tool wear and 0.221 µm surface roughness are discovered at a spindle speed of 1194 r/min and a feed rate of 358 mm/min using MQL cooling method. Across the length of the cut, the resultant cutting force rises with increasing feed rates and reducing spindle speeds. Meanwhile, surface roughness correlates positively with spindle speed and feed rate. The MQL cooling strategy proved effective at medium to low feed rates, reducing cutting force, tool wear, and surface roughness, but benefits decline at high speeds when paired with high feed rates.