The influence of the application of EP additive in the minimum quantity cooling lubrication method on the tool wear and surface roughness in the process of turning 316L steel

Abstract

The paper presents the influence of the application of the EP additive based on pure phosphor in minimum quantity cooling lubrication. During investigation, three methods of cooling the cutting zone have been applied in the process of turning 316L steel: dry machining, MQCL, MQCL + EP. The wear of the tool depending on the cooling method has been monitored, as well as its influence on the machined surface roughness. Scanning analysis has shown formation of a tribofilm as result of the application of the EP additive on the surface of a plate with (Ti, Al) N coating deposited by the PVD method. Experimental evidence suggests that the application of the MQCL + EP method results in reduction of the VBB parameter as compared to dry machining and cooling with emulsion mist up to the moment of the tool coating damage. It has been found that, as result of the application of the EP additive in the MQCL method, after damage of the (Ti, Al) N coating rapid increase of the tool wear takes place and, consequently, increase of the machined surface, which is due to the reaction with the base material (sintered carbide). This is caused by the chemical action of pure phosphor without the carbon matrix on the exposed area of the tool made of sintered carbide; the latter appears as result of adhesive wear of the coating.