Research on effect of ultra-high pressure coolant supplied from flank face in end milling of Ti-6Al-4V supported by CFD simulations

Abstract

In end milling of difficult-to-cut material such as Ti-6Al-4V, thermal wear is one of the main reasons leading to short tool life. High temperature occurred at the cutting zone during cutting process advances adhesion wear and diffusion wear at rake face, accelerates thermal plastic deformation. Furthermore, high temperature could also accelerate flank wear and promote adhesion wear at flank face. Consequently, machining precision of tool will degrade. Ultra-high pressure coolant (UHPC) is one of the well-known cooling/lubrication methods to solve this problem. In this paper, effect of UHPC on end mill flank face have been studied. To accomplish this, we designed an end mill with flank face coolant supplied from a close distance. The influence of coolant nozzle's direction has been studied by computational fluid dynamics (CFD) simulations. The result explains how the direction of the coolant nozzle impact on flow condition on the tool surface. The end mill was manufactured based on simulations by additive manufacturing. Experimental results including flank wear, surface roughness and cutting temperature demonstrate advantages of UHPC in end milling compared to dry cutting and flood coolant. The micro morphology of the worn areas on flank face and rake face further supports the advantages of UHPC.