Review Of Cryogenic Machining: Effect on Tool Wear and Tool Life in Turning and Milling

High-performance engineering alloys, including titanium alloys (Ti-6Al-4V), nickel-based superalloys (Inconel 718), and hardened bearing/tool steels (AISI 52100, AISI D2), are vital for aerospace, automotive, petrochemical, and biomedical industries due to their high mechanical strength, fatigue endurance, and corrosion resistance. However, their low thermal conductivity, high hardness, severe chemical affinity, and work-hardening tendencies lead to extreme cutting zone temperatures exceeding 800 °C to 1000 °C, rapid flank/crater wear, and poor surface integrity. Traditional flood cooling methods rely on petroleum-derived mineral oil emulsions that create hazardous airborne aerosols, environmental disposal hazards, and significant recycling costs. Cryogenic cooling utilizing liquid nitrogen (LN2, boiling point: -195.8 °C) and liquid carbon dioxide (LCO2, delivered under saturation pressure) has emerged as a premier sustainable thermal management strategy This review provides a comprehensive analysis of cryogenic machining mechanisms, heat transfer dynamics, tool wear evolution, process forces, surface roughness, and techno-economic sustainability. Fundamental phenomena such as the suppression of the Leidenfrost vapor barrier via high velocity jet impingement, temperature-dependent surface heat transfer coefficients, and speed-sensitive tool wear regimes are examined. Furthermore, hybrid lubrication-cooling synergies, life-cycle carbon emissions, and finite element modelling uncertainties are evaluated to establish an authoritative roadmap for green manufacturing.