Investigation of sustainable machining of Ti-6Al-4V using graphene enhanced minimum quantity lubrication

Titanium alloys such as Ti-6Al-4V are widely used in aerospace, biomedical, and defense industries due to their excellent strength-to-weight ratio and corrosion resistance.However, their low thermal conductivity, high chemical reactivity at elevated temperatures, and hardness pose significant machining challenges, often leading to increased tool wear and poor surface quality.While traditional flood cooling techniques can address these issues, they introduce environmental and health hazards.As an eco-friendlier alternative, the Minimum Quantity Lubrication (MQL) technique has gained traction.Recently, nanofluids especially those enhanced with g nanoparticles have shown promise for improving thermal conductivity and lubrication in machining.This study investigates the effects of cutting speed, feed rate, and nanoparticle concentration on the machinability of Ti-6Al-4V under sustainable machining conditions using nanofluid-assisted MQL (NFMQL).Experiments were conducted on a CNC lathe with three lubrication conditions: pure MQL, 0.5% wt.GNP-enhanced fluid, and 1.0% wt.GNP-enhanced fluid.Surface roughness, flank wear, and chip morphology were evaluated at cutting speeds of 80, 100, and 120 m/min and feed rates of 0.12, 0.18, and 0.24 mm/rev.The results demonstrate that the addition of 0.5% GNP significantly improves surface quality and reduces tool wear.According to Taguchi S/N analysis, the optimal conditions for minimizing surface roughness were a cutting speed of 80 m/min, a feed rate of 0.18 mm/rev, and 0.5% GNP concentration.Microscopic examinations confirmed less tool wear with 0.5% GNP due to improved lubrication and smoother chip flow.Furthermore, chip morphology analyses revealed that increasing feed rate raised chip peak height, while higher cutting speeds reduced peak height and valley depth due to improved thermal stability.