End milling of stainless steel and titanium alloy in an oil mist environment

This paper discusses the utilization of the minimum quantity lubrication (MQL) method in end milling using a coated carbide tool for stainless steel and titanium alloy workpieces. The effects of MQL were mainly evaluated by tool flank temperature, cutting force, tool wear behavior, and surface roughness. In MQL cutting of stainless steel and titanium alloy at cutting speed v = 25 m/min, the tool flank temperature decreased by approximately 50 and 100 °C, respectively, in comparison with dry cutting. The effect of MQL on tool flank temperature was especially pronounced at low-cutting speeds. Conversely, the tool flank temperature in MQL cutting of titanium alloy was higher than that of dry cutting at v = 100 m/min or more. In high-speed cutting of titanium alloy, it was observed that several chips had adhered to the cutting edge of the rake face, which reached a high temperature due to the heat generated by cutting. In the cutting of titanium alloy, the tool flank temperature at both a higher feed rate and depth of cut was lower than that in high-speed cutting under conditions where the cutting efficiency was the same. Peeling of the coating film covering the tool in dry and air-blow cutting of stainless steel and titanium alloy was more pronounced than that in MQL cutting. The surface roughness was greatly improved by supplying an oil mist in low-speed cutting of stainless steel.