Patent ID: 8481145

Claim:
A sintered cubic boron nitride tool comprising a cubic boron nitride, a binder phase and inevitable impurities, wherein the sintered cubic boron nitride tool has a relief surface, a rake surface, a chamfer honing surface, and a round honing surface formed at an edge line which crosses the relief surface and the chamfer honing surface, the round honing surface having a radius of curvature R in the range of 10 to 50 μm, and a ratio of PR to PC satisfies the relation of 1.2≦PR/PC≦8.0, wherein: PR is a ratio of LRC to LRB; PC is a ratio of LCC to LCB; S is a reference length at least five times an average particle size of cubic boron nitride; LRC is a total length of profile curves of cubic boron nitride included in the reference length S of the round honing surface; LRB is a total length of profile curves of the binder phase included in the reference length S of the round honing surface; LCC is a total length of profile curves of cubic boron nitride included in the reference length S of the chamfer honing surface; and LCB is a total length of profile curves of the binder phase included in the reference length S of the chamfer honing surface.