Performance assessment of pCBN and bCBN tools in machining of high-chromium white cast iron

This paper presents an experimental evaluation of the performance of cubic boron nitride (CBN) tools in the machining of high-chromium white cast iron. Two types of CBN tool materials were evaluated in the tests, including polycrystalline cubic boron nitride (pCBN) and binder-less crystalline cubic boron nitride (bCBN). Performance in terms of the levels of cutting forces, tool wear, surface roughness and process stability was evaluated during and after cutting tests. The work materials used in the cutting tests included two groups with chemical compositions of two levels of carbon silicon (lower C-Si and higher C-Si) in as-cast and hardened states, respectively. Test results indicate that the cutting tool materials clearly exhibited different behaviour in the machining of high-chromium white cast iron. The pCBN tools demonstrated lower tool wear rates than the bCBN tools but had higher roughness levels on the workpiece surfaces. The cutting tools also behaved differently according to the different levels of C-Si content and heat treatment of the work materials. In addition, the study reveals the mechanism of the interactions between CBN tools and high-chromium white cast iron under a range of machining parameters.