Cutting performance of CBN tools in machining of austempered bainitic spheroidal graphite cast iron.

As one of the difficult-to-machine materials, austempered bainitic spheroidal graphite cast iron (FCD 1000 A) have been machined so far only by grinding. In the present study, cutting of the FCD 1000 A was tried using CBN tools. Cutting performance of the tools was investigated through determining the optimum combination of condition for cutting and binding phase for the tool materials. For fine cutting of the FCD 1000 A, the optimum cutting temperature was determined as 1 100 K and the best material for the binding phase of CBN tool was TiC from both tool life and surface roughness points of view. From the temperature dependence of flank wear rate, wear behavior of the tool could be classified into two temperature regions, A and B. In the region A, a scratch mark was abundantly observed on the wear surface of the tool due mainly to microspalling of c-BN particles. In the region B, it was significantly observed that the tool wear was controlled by falling-off of adhering particle from the cutting edge.