As an alternative approach to meeting the requirements of high-hardness endmilling and copymilling operations, some cutting-tool manufacturers have developed either negative, or dead-flat, insert geometries aimed at providing greater edge strength. To obtain the necessary cutting speeds, PCBN-tipped (polycrystalline cubic boron nitride) inserts are used, which, in effect, remove the hardened work material by rubbing or burnishing, rather than cutting. Though this machining technique creates tremendous heat in the insert, the PCBN cutting material is able to withstand it. For this reason, Carboloy also offers PCBN-tipped inserts as an alternative to the PVD multi-layer micrograin carbides. From our perspective, however, the real value of PCBN for high-speed finishing of hardened materials lies in the future, when we can expect requirements for still higher cutting data. In the meantime, the PVD multi-layers with ultra-sharp edges offer proven capabilities to meet today's requirements as well as or better than PCBN, and at significantly lower cost.(end)