Surface Finish Evaluation of AISI P100 Steel after Grinding with MQL Technique with Different Flow Rates

Grinding operation is a finishing process often employed when high precision and narrow geometric tolerances are required. These requirements can be achieved only if cutting conditions are properly selected, especially the cooling-lubrication technique. In general, grinding is performed in presence of cutting fluid, however, due to the environmental impacts and costs of the conventional coolant delivery technique (flow rates from 4 L/min to 300 L/min), alternative cooling-lubrication techniques have been developed on restriction of the coolants use. Among the several techniques, MQL (minimum quantity of lubricant) technique has received special attention from machining users because of its advantages in terms of surface quality of workpiece and drastic reduction in use of coolant. In this context, this paper evaluated the performance of the MQL technique as compared to the flood coolant in peripheral surface grinding of AISI P100 (VP100) steel with conventional aluminum oxide grinding wheel in relation to the surface roughness (Ra and Rz). Input parameters tested were equivalent chip thickness (0.09 μm, 0.18 μm and 0.27 μm) and flow rate of the cutting fluid (60 mL/h, 150 mL/h and 240 mL/h) of the MQL system. Results showed that the grinding with MQL technique provided lower surface roughness values compared to conventional flood cooling, especially when machining under the intermediary cutting conditions. Also, with exception of h_eq of 0.09 µm, the MQL technique resulted in lower values of Rz parameter as compared to the conventional coolant technique, regardless of the flow rate tested.