US Patent 10024112 Superhard cutter

A cutter comprises a superhard construction, the cutter having a cutting edge defined by a rake face, and a flank extending therefrom. The cutter also has first and second regions, the first region abutting the second region along a boundary, the first region having a different material composition from the second region. At least the second region comprises superhard material, the material of the first region has a different coefficient of thermal expansion (CTE) from the material of the second region. The second region extends around the peripheral edge of the first region defined by the boundary to form a collar therearound, the first region and/or the second region extending to and/or forming at least a part of the rake face.