Feasibility of Supercritical Carbon Dioxide Based Metalworking Fluids in Micromilling

This article investigates the feasibility of using supercritical carbon dioxide based metalworking fluids (scCO₂ metalworking fluids (MWFs)) to improve micromachinability of metals. Specifically, sets of channels were fabricated using micromilling on 304 stainless steel and 101 copper under varying machining conditions with and without scCO₂ MWF. Burr formation, average specific cutting energy, surface roughness, and tool wear were analyzed and compared. Compared to dry machining, use of scCO₂ MWF reduced burr formation in both materials, reduced surface roughness by up to 69% in 304 stainless steel and up to 33% in 101 copper, tool wear by up to 20% in 101 copper, and specific cutting energy by up to 87% in 304 stainless steel and up to 40% in 101 copper. The results demonstrate an improvement in micromachinability of the materials under consideration and motivate future investigations of scCO₂ MWF-assisted micromachining to reveal underlying mechanisms of functionality, as well as to directly compare the performance of scCO₂ MWF with alternative MWFs appropriate for micromachining.