A Study on Prototype of End Mill for Ultra-High Pressure Coolant Supplying from Flank Surface Side Using Fluid Simulation

Abstract

In machining of difficult-to-cut materials, increase of temperature in tool tip is one of the main reasons resulting in short tool life. Heat can promote adhesion wear and diffusion wear at rake face, accelerate thermal plastic deformation. Furthermore, heat could also accelerate flank wear and promote adhesion wear at flank face. As a result, machining precision of tool will become worse. The common method applied to reduce temperature of tool tip is cutting with coolant supply. Conventional coolant supply is only effective to cool down areas around cutting zone with low pressure when cutting speed is low. When higher cutting heat is generated, the fluid can be vaporized to form a high-temperature steam barrier and most of the fluid suppled does not penetrate in the area adjacent to cutting zone. However, high pressure coolant might overcome the disabilities of flood coolant in milling. Present relevant research focused on effect of ultra-high pressure coolant (UHPC) on rake face mainly. In this study, to improve the machining efficiency (processing time) by using end mill, a prototype of end mill with internal coolant nozzles (both rake side and flank side) was designed and CFD (Computational Fluid Dynamics) simulations were conducted to find out the relatively effective coolant supply method for coolant penetrating in cutting zone of flank face mainly. Beyond that, effects of UHPC on rake face were also examined. During the latest experiments, tool wears, cutting length and roughness of work material were measured under both dry and wet cutting conditions. For wet cutting, three kinds of coolant supply method were applied: flank face only, rake face only and both rake face and flank face. For each method, coolant was supplied under the pressure of 3MPa, 7MPa, 14MPa and 20MPa. Tool wear was significantly reduced, and roughness was improved by high pressure coolant supply.