Optimization of titanium alloys turning operation in varied cutting fluid conditions with multiple machining performance characteristics

Abstract

Titanium alloys are widely used in engineering applications due to their superior properties. However, machining of titanium alloys has always been a problem due to high cutting temperatures. Though flood lubrication is a solution, it is not encouraged in sustainable machining. This paper describes a study that used sustainable lubricants in turning of Ti6Al4V. Soybean oil-based lubricants were used with/without addition of micro-graphite particles in minimum quantity lubrication (MQL) at the rate of 40 mL/h. PVD-coated carbide tools were used for machining under different cutting conditions. To minimize the number of experiments, Taguchi’s L9 array is used. Five different lubricating conditions, namely, dry machining, commercial cutting fluid with and without micro-graphite, and soybean-based cutting fluid with and without graphite, were studied. Tool wear, cutting forces, and surface roughness were measured in the experiments. ANOVA analysis was carried out to estimate the optimal conditions. Among the considered combinations, it was found that the cutting speed of 90 m/min, feed of 0.3 mm/rev, and depth of cut of 0.5 mm were optimal for overall machining performance. Confirmation tests were carried out at these conditions to validate the findings.