The present invention relates to a cutting tool, which performs, like a drill or a ball end mill, cutting while rotating in a state in which the center of the tip end is in contact with a work material, and includes a wear-resistant layer formed at the tip end thereof, wherein a portion of the wear-resistant layer is selectively removed through tip end polishing from the center of the tip end of the drill or the ball end mill to a predetermined area, so as to restrain micro-brittle wear generated in an ultra-low speed region, and thus remarkably improving the cutting lifespan of the cutting tool such as the drill or the ball end mill.

A coating for carbide substrates employs a nanostructured coating in conjunction with a non-nanostructured coating. The nanostructured coating is produced by the addition of a refining agent flow, particular hydrogen chloride gas, during deposition, and may be produced as multiple individual titanium and titanium-based nanostructured layers varying functional materials in a series. The combination of a nanostructured coating and non-nanostructured coating is believed to produce a cutting tool insert that exhibits longer life. Pre-treating the substrate with a mixture of compressed air and abrasive medium prior to coating the substrate and post-treating the coated substrate with a mixture of water and abrasive medium after the coating process is believed to further enhance the wear resistance and usage life of the cutting tool.

The present invention relates to a cutting tool, which performs, like a drill or a ball end mill, cutting while rotating in a state in which the center of the tip end is in contact with a work material, and includes a wear-resistant layer formed at the tip end thereof, wherein a portion of the wear-resistant layer is selectively removed through tip end polishing from the center of the tip end of the drill or the ball end mill to a predetermined area, so as to restrain micro-brittle wear generated in an ultra-low speed region, and thus remarkably improving the cutting lifespan of the cutting tool such as the drill or the ball end mill.

A coated cutting tool comprising: a substrate; and a coating layer formed on a surface of the substrate, wherein: the coating layer comprises a lower layer, an intermediate layer and an upper layer in this order from the substrate side; the lower layer comprises one or more Ti compound layers containing a Ti compound of Ti and an element of at least one kind selected from the group consisting of C, N, O and B; and the intermediate layer comprises an -Al.sub.2O.sub.3 layer containing -Al.sub.2O.sub.3; and the upper layer comprises a TiCN layer containing TiCN; an average thickness of the coating layer is within a specific range, and an average thickness of the upper layer is within a specific range; in a cross section perpendicular to the surface of the substrate, the grains in the TiCN layer constituting the upper layer satisfies a specific condition.

Provided is a ceramic sintered body having high wear resistance and chipping resistance. Also provided are an insert, a cutting tool and a friction stir welding tool, each of which uses such a high-performance ceramic sintered body. The ceramic sintered body includes Al.sub.2O.sub.3 (alumina), WC (tungsten carbide) and ZrO.sub.2 (zirconia), wherein Zr (zirconium) element is present at either one or both of: (1) a grain boundary between crystal grains of the Al.sub.2O.sub.3; and (2) a grain boundary of crystal grains of the Al.sub.2O and crystal grains of the WC, wherein the ceramic sintered body contains 55.0 to 97.5 vol % of the WC, 0.1 to 18.0 vol % of the ZrO.sub.2, and the balance being the Al.sub.2O.sub.3, and wherein the ZrO.sub.2 is in a phase of tetragonal structure (T) or a mixed phase of tetragonal structure (T) and monoclinic structure (M).

A coated cutting tool including a substrate and a coating layer formed on the substrate, wherein the coating layer comprises an alternately laminated structure of a first layer and a second layer, the first layer contains a compound having a composition represented by (Al.sub.aM.sub.bTi.sub.1-a-b)N (M represents at least one of a Nb element and a Ta element, and 0.75a0.90 and 0.00<b0.20 are satisfied), the second layer contains a compound having a composition represented by (Al.sub.cM.sub.dTi.sub.1-c-d)N (M represents at least one of a Nb element and a Ta element, and 0.75c0.90 and 0.00d0.20 are satisfied), at least one of a and c is 0.80 or more, and the average thickness of the alternately laminated structure is 0.5 m or more and 5.0 m or less.

A coated cutting tool comprising a substrate and a coating layer formed on a surface of the substrate, wherein: the coating layer comprises at least one -type aluminum oxide layer; and, in the -type aluminum oxide layer, when regarding a texture coefficient of a (0,0,6) plane as a TC18 (0,0,6), and also regarding a texture coefficient of a (0,0,12) plane as a TC18 (0,0,12), the TC18 (0,0,6) is the highest texture coefficient and the TC18 (0,0,12) is the second highest texture coefficient.

A cutting edge tip of a cubic boron nitride sintered body has improved joint strength to a substrate of a cemented carbide. A cutting edge tip of a cubic boron nitride sintered body has improved crater wear resistance. A tool 10 of the present invention includes a substrate 12 of a cemented carbide and a cutting edge tip 14 of a cubic boron nitride sintered body joined to the substrate 12. The cutting edge tip 14 has a thickness covering an upper surface 12a to a lower surface 12b of the substrate 12. The cubic boron nitride sintered body contains 50 volume % or more and 95 volume % or less of cubic boron nitride and 5 volume % or more and 50 volume % or less of a binder phase. The cubic boron nitride has an average grain size of 1.0 m or more and 6.0 m or less.

An insert includes a first surface having a corner portion, a second surface, a third surface, and a cutting edge. The cutting edge is provided with a first cutting edge located on the corner portion and a second cutting edge adjacent to the first cutting edge, and the third surface is provided with a first portion located along the first cutting edge and a second portion located along the second cutting edge. the second portion includes a first region having a first end portion and a second end portion, and a second region having a third end portion and a fourth end portion. An inclination angle 212 at the second end portion is greater than an inclination angle 211 at the first end portion, and an inclination angle 222 at the fourth end portion is smaller than an inclination angle 221 at the third end portion.

A cutting insert according to an aspect includes a top surface and a side surface. At least a part of a ridge line where the top surface and the side surface intersects is a cutting edge. The cutting edge includes a first portion located at a corner portion, a second portion adjacent to the first portion, a third portion close to the second portion, a fourth portion close to the third portion, and a fifth portion adjacent to the fourth portion. When viewed from directly above, a curvature radius of the second portion is less than a curvature radius of the first portion, a curvature radius of the third portion is greater than the curvature radius of the first portion, and a curvature radius of the fourth portion is less than the curvature radius of the third portion.