Study of eco-friendly emulsions in minimum quantity lubrication-assisted micromilling of Ti6Al4V

The increasing requirement for extremely complex and precise miniature features in a variety of products may be achieved by micromilling operations, which are scaled-down versions of traditional macromilling. Nevertheless, it exhibits exceptionally poor machinability when micromilling particularly hard-to-cut titanium alloys. This study investigates the effects of eco-friendly soybean oil-water (SO + DIW) emulsion and conventional paraffin oil water (PO+DIW) emulsion-based minimum quantity lubrication (MQL) at varying flow rates (60, 125, and 250 ml/h) on cutting force, surface roughness, and burr formation during the micromilling of Ti6Al4V. Micromilling experiments were conducted at low (10,000 rpm) and high (35,000 rpm) spindle speeds to investigate the combined effect of emulsion flow rate and spindle speed on the micromilling performance of Ti6Al4V alloy. The SO + DIW emulsion produced the best results when the flow rate was 60 ml/h, and the lowest micromilling responses (surface roughness, cutting force, and burr formation) were obtained when the spindle speed was 10,000 rpm. It was observed that for the SO + DIW emulsion MQL-assisted micromilling of Ti6Al4V, there was an almost 88.5% average reduction in resultant cutting force, a 72% average reduction in surface roughness, a 71.25% average reduction in top burr width in up milling, and an 86.78% average reduction in top burr width in down milling when compared to the dry condition. Whereas PO + DIW emulsion provides a reduction of 81.67%, 74.67%, 76.04%, and 78.84% in resultant cutting force, surface roughness, and top burr width in the up milling and down milling sides, respectively, compared to the dry condition.