Sustainable milling of Ti–6Al–4V: A trade-off between energy efficiency, carbon emissions and machining characteristics under MQL and cryogenic environment

The urgent need for an innocuous and sustainable machining system is essential in this modern manufacturing era. Therefore, a study is devoted to fulfilling a missing bridge between sustainability measures (process time, specific cutting energy, energy efficiency, carbon emissions) and machining characteristics (tool wear, surface roughness, cutting temperature) in the milling of Ti–6Al–4V. The experiments are organized by implementing the minimum quantity lubrication (MQL), CO2-snow, and cryogenic-LN2 under varying end-mill geometries and cutting conditions. The results obtained have underscored the outperformed CO2-snow followed by cryogenic-LN2, MQL, and dry cutting conditions regarding sustainability measures and machining characteristics. The up-milling of 42° helix angle cutter and CO2-snow outperformed by reducing 47% of surface roughness, 50% extended tool life compared to dry cutting. The cryogenic-LN2 provided minimum cutting temperature flowed by CO2-snow, MQL, and dry cutting, respectively. Besides, the up-milling tool of the 42° helix angle provided better machining characteristics than the down-milling tool of the 30° helix angle. The feasibility of CO2-snow was comprehensively expressed and implemented in the milling process to extend the advanced analysis.