A novel cold air electrostatic minimum quantity lubrication (CAEMQL) technique for the machining of titanium alloys Ti–6Al–4 V

The milling of titanium alloys is usually associated with a high cutting temperature and severe tool wear. Therefore, flood cooling technologies have been conventionally employed to prolong the tool life and improve the quality of the machined surface. However, the negative impact on the environment and waste disposal problems caused by the vast quantity of metalworking fluids used in the process have become significant. In this study, a new machining method called “cold air electrostatic minimum quantity lubrication (CAEMQL)” is proposed for machining titanium alloy Ti–6Al–4 V. The milling performance of CAEMQL was systematically assessed in terms of cutting force, cutting temperature, surface roughness, tool life, tool wear, and chip morphology, using minimum quantity lubrication (MQL), electrostatic minimum quantity lubrication (EMQL), and cold air minimum quantity lubrication (CAMQL) as benchmarks. It was found that CAEMQL resulted in improved critical heat flux and steady-state heat transfer performance compared to MQL, EMQL, and CAMQL, which thus produced a lower milling force, smaller milling temperature, better surface quality, and less tool wear. The degree of chip segmentation was enhanced with less deformation under CAEMQL due to its synergistic cooling and lubrication effect.