Impact of Cryogenic Machining on Ti-6Al-4V Titanium Alloy

Conventional cutting fluids have long been essential in manufacturing processes, despite their environmental drawbacks and sustainability concerns. However, a promising and eco-friendly alternative has emerged in the form of cryogenic cooling. This innovative method, utilizing liquid nitrogen or liquid carbon dioxide as coolants, has demonstrated remarkable success in aerospace component production, offering superior quality results while addressing environmental challenges. In turning experiments, cryogenic cooling with liquid nitrogen produced similar results to emulsion flood-cooling in surface integrity, roughness, microstructure, and residual stresses. However, tool wear was slightly higher with cryogenic cooling due to limited coolant flow. Face milling with liquid carbon dioxide showed delayed tool wear mechanisms compared to emulsion flood-cooling, with comb crack propagation notably hindered. Higher coolant flow rates improved tool life significantly, especially with liquid carbon dioxide, and the gap in tool life between cryogenic and emulsion cooling decreased at higher cutting data. Moreover, at elevated cutting data, the gap in tool life between cryogenic cooling and traditional flood-cooling diminished, highlighting the potential of cryogenic cooling to match or even surpass conventional methods in machining performance. This research illuminates the significant impacts of cryogenic cooling on surface integrity, tool wear mechanisms, and overall machining efficiency, reaffirming its position as a sustainable and effective solution in titanium alloy machining.