Performance of CBN cutting tools in facing of age hardened inconel 718

Inconel 718 is widely used in aerospace industries because of their ability to withstand excessive loads even at elevated temperatures. But this property makes it one of the most difficult to machine material resulting in lower cutting speeds and hence lower productivity and high costs. High speed machining (HSM) using cubic boron nitride (CBN) tools is an alternative to improve the productivity. The performance of CBN tools in the high speed facing operation of age hardened Inconel 718 for finishing application has been investigated. Crater break through at the cutting edge especially at the depth of cut notch region (DOCN) caused by a diffusion wear mechanism has been found to be the major cause for tool failure. It is concluded that there would be a significant improvement in the ability of CBN tools to cut Inconel 718 if it were possible to increase their resistance to diffusion at higher temperatures.