Experimental study of the influence of graphene platelets on the performance of grinding of SAE 52100 steel

The use of coolant during grinding process is indispensable to avoid and/or attenuate any possible thermal damages on the workpiece. However, the conventional cooling-lubrication technique (flood system) has some drawbacks, especially regarding the fact that most of the coolants are harmful to environment and human healthy, besides higher costs, maintenance, and disposal. Therefore, not only the search for new methods that contribute in reducing the amount of coolant in grinding process is crucial, but also the search to improve techniques consolidated in machining processes, such as the minimum quantity lubrication (MQL). In this sense, the improvement of the thermal properties and lubrication of the coolants by nanoparticles has been one of the promising alternatives. The present work brings a contribution for bearing manufacturing industry by analyzing the effect of the concentration of multilayer graphene platelets (MLG) dispersed in coolant on the surface finish and morphology of the SAE 52100 bearing steel after grinding under various conditions. MLG were dispersed in an environmentally friendly cutting fluid (semi-synthetic vegetable based) and delivered via the MQL technique. Tests with the traditional MQL technique (oil without graphene) were also carried out for comparisons. Electric power was also monitored. The results showed that the low concentrations of MLG improved the tribological conditions in the cutting zone that resulted in better surface finish and morphology, but no influence on the electrical power was observed. The MLG proved to be a practical alternative in relation to traditional MQL technique in grinding of the SAE 52100 bearing steel.