The Effect of Cutting Environments When High Speed Ball Nose End Milling Inconel 718

The paper briefly touches on the machinability of aerospace alloys and reviews recent high speed machining (HSM) literature detailing aerospace research and cutting fluid application techniques (high pressure, spray mist, etc.). Experimental work is subsequently detailed on the effect of cutting environment and cutting speed on tool life, cutting forces and temperatures (using both implanted wire and foil K‐type thermocouples), when high speed ball nose end milling Inconel 718TM. Tests involved the use of cemented tungsten carbide tools, coated with a monolayer of TiAlN, on a 20,000 rpm prismatic machining centre. When operating at a cutting speed of 90 m/min (5,064 rpm), with high pressure flood cutting fluid (70 bar, 26 l/min), tool life was up to 123% longer than with other cutting environments. Temperature measurements indicated that high pressure fluid application substantially reduced workpiece temperatures from 320 °C when cutting dry to 175 °C. Similiar tool life and temperature trends occurred at cutting speeds of 150 and 210 m/min. Inconel 718's ability to retain its strength at high temperature, was such that cutting forces increased with cutting speed, despite higher interface temperatures.