Effect of cutting parameters and CO2 flow rate on surface integrity in milling AISI 316L steel using supercritical CO2

The machining challenges commonly experienced in the milling of stainless steels, such as the formation of built-up material on the cutting tool edge and the low thermal conductivity resulting in high heat generation within the cutting zone, require the application of a lubricating cutting fluid. Manufacturing industry traditionally uses an oil-based coolant for dissipating frictional heat and reducing chip adhesion to the cutting tool; however, this is not environmentally sustainable. In this study, a design of experiment (DoE) approach was employed to investigate the impact of feed per tooth, cutting speed, and the flow rate of supercritical carbon dioxide (scCO2) on cutting forces and surface integrity during face milling of AISI 316L. As expected, it was observed that surface residual stresses increased with an increase in the feed rate. The surface roughness remained unaffected by changes in scCO2 flow rate and variations within the range of machining parameters considered in the experimental design. ScCO2 demonstrated its potential as a sustainable coolant substitute in the industrial machining of austenitic stainless steels.