Sumitomo has introduced its first cutting insert produced from NCB100, an ultra-hard binder-less polycrystalline cubic boron nitride (BL-PCBN) cutting material, using a newly devised method of direct conversion sintering.
Binders and the volumes used in producing cutting inserts can have a significant influence on mechanical and thermal properties, and hence performance, an area that Sumitomo’s binder-less development overcomes. Here, the NCB100 insert has a distinct advantage as its hardness far surpasses that of single crystals, as well as more traditional sintered compacts. The latest insert is also free from any influence of the cleavage and anisotropy (strength variation when used in different directions) associated with single crystals.
NCB100 has high levels of hardness, strength and thermal conductivity that will surpass conventionally sintered PCBN compacts containing binder materials, says Sumitomo. As a result, NCB100 creates high orders of wear resistance and stability from the cutting edge of the insert. This capability is critical when machining difficult, non-ferrous materials such as titanium alloys, cemented carbides, hard ceramics, and Ni-based heat-resisting and cobalt-chrome (Cr-Co) alloys used in medical applications.
Sumitomo reports that NCB100 has been proven in finish-turning trials against established carbide grades, where significant levels of tool life improvements have been achieved despite inserts being run at cutting speeds up to 200 m/min. The material has also been found to be highly stable when finish-turning Co-Cr alloys used, for instance, in medical hip joints. In addition, the insert material can be applied to high-speed milling applications such as the finishing of titanium alloys and Ni-based heat-resisting alloys, at speeds up to 700 m/min.
