Cryogenic Drilling of Ti–6Al–4V Alloy Under Liquid Nitrogen Cooling

Abstract

This article is focused on experimental study of the effects of cryogenic liquid nitrogen (LN2) coolant during drilling of Ti–6Al–4V alloy material with three different levels of cutting speed (Vc) and feed rate (f) at a constant depth. Cutting temperature (T), thrust force (Fz), torque (Mz), surface roughness (Ra), and hole quality are the output responses investigated by using cryogenic LN2 coolant compared with a wet coolant. Tool wear and chip morphology were examined with the changes in cryogenic LN2 coolant. It is found that cryogenic LN2 coolant results in lowering cutting zone temperature which helps more removal of heat from the cutting zone. Lower thrust forces and surface roughness were observed due to less friction and better chip breaking in cryogenic LN2 condition. Also better chipping results in improvement in hole quality, viz., circularity and cylindricity in cryogenic LN2 condition. Less serration and uniform segmentation results in better chip morphology and no damage to the cutting inserts resulted in improved tool life in cryogenic LN2 condition. The main application of cryogenic LN2 coolant in the cutting zone provides better lubrication and is more effective than wet coolant. The effects of this investigation show that cryogenic LN2 coolant is an alternative approach for a wet coolant in the drilling process.