Sustainable and efficient cooling in titanium milling for dental applications: A study on supercritical CO2 + MQL with focus on tool wear and surface topography

Titanium alloys, commonly used in dental implants due to their biocompatibility and mechanical properties, pose significant machining challenges. Their low thermal conductivity leads to elevated cutting temperatures, accelerated tool wear, and compromised surface integrity. This study investigates the application of supercritical carbon dioxide (scCO 2 ) combined with minimum quantity lubrication (MQL) as an advanced cooling and lubrication strategy for milling titanium dental implant bridges, comparing its performance with conventional emulsion-based flood cooling. Milling experiments on dental geometries under varying cutting parameters evaluated tool wear, surface integrity, and material removal rates. The results reveal that the scCO 2 + MQL approach significantly reduces tool wear, improves surface quality, and enhances material removal rates compared to emulsion cooling. Specifically, tool flank wear decreased by over 190 %, while material removal rates increased by approximately 68 % during extended milling operations. These findings underscore the potential of scCO 2 + MQL to improve precision, efficiency, and sustainability in the manufacturing of dental implants. • Innovative Cooling: Superior performance of scCO₂ + MQL over emulsion cooling in milling titanium dental implants.Superior performance of scCO₂ + MQL over emulsion flood cooling in milling titanium dental implants. • Extended Tool Life: Reduced tool wear by up to 190 %, extending tool life in dental milling. • Better Surface Quality: Produces smoother, cleaner surfaces with less adhesion. • Higher Efficiency: Increased material removal rate by 68 % and reduced cutting time by 40 %. • Eco-Friendly: Lowering environmental impact in dental manufacturing.