Advances in precision manufacturing towards eco-friendly grinding process by applying MQL with cold air compared with cooled wheel cleaning jet

With the evolution of the sustainable industry, the grinding process seeks to follow the requirements to continue to be highly employed when precision and low-dimensional tolerances are required in the workpieces. In this way, the cutting fluids used in the process, which are essential for a good surface finish, are the main impasse to ensure that the process becomes eco-friendly. Therefore, a widespread lubri-refrigeration method in the industry is the flood technique, which uses a lot of fluid to reduce the high temperatures generated during grinding. However, the use of the flood method generates many undesirable residues that affect the machine operator, the environment, and production costs. Thus, several alternatives have emerged to address these problems, for example, the minimum quantity of lubricant (MQL), the wheel cleaning jet system (WCJ), and the application of cooled air (CA). Therefore, this work sought to analyze the combination of these systems (MQL+CA, MQL+WCJ, and MQL) in the grinding of AISI 4340 steel using an aluminum oxide wheel (Al 2 O 3 ) and to verify their performance compared with the flood method, in addition to employing a new method known as cooled wheel cleaning jet (CWCJ). Therefore, the tests of surface roughness (Ra and Rz), roundness error, diametrical wheel wear, G ratio, grinding power, tangential cutting force, and microhardness were performed, and optical, confocal, and scanning electron microscopy also were analyzed. Thus, the results that came closest to the flood method in all tests were achieved by systems that applied grinding wheel cleaning (MQL + WCJ and MQL + CWCJ), being that in the diametrical wheel wear and G ratio the MQL + CWCJ even managed to surpass it. Besides, the MQL+CA union showed better values when compared with MQL without any assistance. Thus, applying MQL with helper systems, mainly CWCJ, contributed to a more economical, efficient, and sustainable grinding process.