Impact of Supercritical Carbon Dioxide Metalworking Fluids on Tool Life in Turning of Sintered Steel and Milling of Compacted Graphite Iron

This paper investigates the influence of supercritical carbon dioxide (scCO₂) metalworking fluids on tool wear in two automotive manufacturing processes. scCO₂ is a low-cost minimum quantity lubrication (MQL) system with excellent cooling characteristics. In valve seat machining of sintered steel with cubic boron nitride (CBN) inserts, scCO₂ reduced tool wear by up to 25% and cutting forces by 10% when compared with the benchmark water-based flood metalworking fluid currently used in production operations. In end milling of compacted graphite iron (CGI) with uncoated carbide inserts, scCO₂ reduced tool wear by up to 50% when compared with the currently used metalworking fluid. These results are consistent with those from other applications that show scCO2-based metalworking fluids have the potential to reduce tool wear and cutting forces when compared with commonly used water-based metalworking fluids. At the same time scCO₂ is environmentally benign, eliminates metalworking fluid maintenance and disposal, and removes the major health risks associated with today’s metalworking fluids.