Supercritical carbon dioxide assisted grinding: influence of grinding wheel porosity on grinding forces, grinding power and surface quality

Abstract Despite their technical necessity in grinding processes, the use of conventional cutting fluids is connected with disadvantages such as environmental drawbacks and occupational health risks. Additionally, the conventionally used flood lubrication has a high demand on peripheral equipment such as pumps and filtration units, leading to a high energy demand. Research therefore suggests alternative strategies such as minimum quantity lubrication (MQL). As grinding is dependent on cooling, MQL has recently been extended by supercritical carbon dioxide (scCO 2 ), providing a sufficient cooling and effectively transporting the MQL fluid to the contact zone. Against this background, in this study, scCO 2 + MQL was used in steel grinding with corundum grinding wheels and compared to flood lubrication using an emulsion. A key research objective was to identify the influence of grinding wheel porosity on process parameters and surface quality. Cutting conditions were varied by changing workpiece speeds and single cutting depths. It was found that regardless of grinding wheel and cutting fluid strategy, surface roughness, power, and forces increase with higher workpiece speeds and single cutting depths. Grinding forces were lower when using scCO 2 + MQL compared to emulsion, whereas surface roughness was lower when using emulsion. Further, it was shown that the grinding wheel porosity significantly influences the process performance. The results reveal that a to certain extend, a higher porosity benefits the outcome of the grinding process in terms of roughness. This requires balancing sufficient grain interaction (lower porosity) as well as a sufficient fluid delivery (higher porosity) to the contact zone, underlining the significance of a tailored tool selection for scCO 2 + MQL usage in grinding.