The Influence of Cutting Fluid Concentration on Surface Integrity of VP80 Steel and the Influence of Cutting Fluid Flow Rate on Surface Roughness of VPATLAS Steel After Grinding

Abstract

The application of cutting fluid in grinding operations is crucial to control temperature levels and prevent thermal damage to the workpiece. Water-based (emulsions and solutions) coolants are used in grinding operations owing to their excellent cooling capability and relatively lower cost compared to neat oils. However, the cutting fluid efficiency is not only dependent on its type, but also on other parameters including its concentration and flow rate. In this context, this work aims to analyze the influence of the coolant concentration and flow rate on the grinding process. Two different workpiece materials for the production of plastic injection moulds were machined: VP80 and VPATLAS steel grades. Six grinding conditions (combinations of depth of cut values of 5, 15, and 25 μm with coolant concentration of 3% and 8%, respectively) were employed in the former, while two grinding conditions were used for the latter. The output parameter used to assess the influence of coolant concentration and flow rate on the grinding operation focused on the integrity of the workpiece materials (surface roughness and microhardness below the ground surface). The results showed that the surface integrity of VP80 after grinding was more sensitive to depth of cut than to cutting fluid concentration. Furthermore, the highest coolant concentration outperformed the lowest one when grinding under more severe conditions. With regard VPATLAS steel, no influence of the coolant flow rate on surface roughness was observed.