A surface coated cutting tool comprises: a tool substrate and a coating layer on a surface of the tool substrate; wherein the coating layer comprises a lower layer, an intermediate layer, and an upper layer, in sequence from the tool substrate toward the surface of the tool. The lower layer comprises an A layer having an average composition represented by formula: (Al.sub.1-xCr.sub.x)N, where x is 0.20 to 0.60; the intermediate layer comprises a B layer having an average composition represented by formula: (Al.sub.1-a-bCr.sub.aSi.sub.b)N, where a is 0.20 to 0.60 and b is 0.01 to 0.20; and the upper layer comprises a C layer having an average composition represented by formula: (Ti.sub.1-α-βSi.sub.αW.sub.β)N where α is 0.01 to 0.20 and β is 0.01 to 0.10; and the upper layer has a repeated variation in W level with an average interval of 1 nm to 100 nm between adjacent local maxima and minima.

A ceramic material includes of β-sialon (Si.sub.(6-z)Al.sub.zO.sub.zN.sub.(8-z)), polytype 15R, an intergranular phase, and yttrium. The polytype 15R includes twin grains.

The use of cryogenic coolant in a machining operation in Ti, Ti-alloys or Ni-alloys together with a cutting tool of a cemented carbide substrate with a gradient surface zone with a thickness of between 50-400 μm is provided. The cemented carbide substrate has a binder phase gradient with the lowest binder phase content in the outermost part of the gradient surface zone and the cemented carbide having graphite. The arrangement leads to a significantly prolonged tool life.

A cemented carbide cutting tool having WC and a low amount of binder phase can be used when machining Ti, Ti-alloys and Ni-based alloys under cryogenic conditions, leading to a significantly prolonged tool life.

A surface-coated cutting tool has a rake face and a flank face, and includes a base material and a coating formed on the base material. The base material has a cutting edge face connecting the rake face to the flank face. The coating includes an aluminum oxide layer containing a plurality of aluminum oxide crystal grains. The aluminum oxide layer includes: a first region made up of a region A on the rake face and a region B on the flank face; a second region on the rake face except for the region A; and a third region on the flank face except for the region B. The aluminum oxide layer satisfies a relation: b−a>0.5, where a is an average value of TC(006) in the first region in texture coefficient TC(hkl), and b is an average value of TC(006) in the second or third region in texture coefficient TC(hkl).

A method for controlling flow localization in machining process is disclosed. By application of a constraint of sufficient level in the deformation zone and modifying the surface boundary conditions, suppression of unsteady flow and flow instabilities is achieved. The method enhances machined component quality by ensuring a uniform deformation state on the machined surface. Machined components are produced by ensuing uniform deformation by adopting constrained-cutting process for suppressing the instabilities and unsteady flow through a pre-determined location of the constraint of the constrained machining process relative to the machining tool.

A tool having a cutting edge that includes a sintered body containing cubic boron nitride. The sintered body integrally and inseparably includes an inner region and a binder phase enriched layer formed on at least part of a surface of the inner region. The inner region includes: 15-90 volume % of cubic boron nitride; and 10-85 volume % of a mixture of a binder phase and impurities. The binder phase enriched layer includes: 90-100 volume % of the binder phase and impurities mixture; and 0-10 volume % of cubic boron nitride; and the binder phase contains at least one kind selected from the group consisting of: at least one element selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Al, Co, Ni and Si; and a compound of the element and at least one element selected from the group consisting of C, N, O and B.

A surface-coated cutting tool has a rake face and a flank face, and includes a base material and a coating formed on the base material. The base material has a cutting edge face connecting the rake face to the flank face. The coating includes an aluminum oxide layer containing a plurality of aluminum oxide crystal grains. The aluminum oxide layer includes: a first region made up of a region A on the rake face and a region B on the flank face; a second region on the rake face except for the region A; and a third region on the flank face except for the region B. The aluminum oxide layer satisfies a relation: ba>0.5, where a is an average value of TC(006) in the first region in texture coefficient TC(hkl), and b is an average value of TC(006) in the second or third region in texture coefficient TC(hkl).

A tool having a cutting edge that includes a sintered body containing cubic boron nitride. The sintered body integrally and inseparably includes an inner region and a binder phase enriched layer formed on at least part of a surface of the inner region. The inner region includes: 15-90 volume % of cubic boron nitride; and 10-85 volume % of a mixture of a binder phase and impurities. The binder phase enriched layer includes: 90-100 volume % of the binder phase and impurities mixture; and 0-10 volume % of cubic boron nitride; and the binder phase contains at least one kind selected from the group consisting of: at least one element selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Al, Co, Ni and Si; and a compound of the element and at least one element selected from the group consisting of C, N, O and B.

The use of cryogenic coolant in a machining operation in Ti, Ti-alloys or Ni-alloys together with a cutting tool of a cemented carbide substrate with a gradient surface zone with a thickness of between 50-400 m is provided. The cemented carbide substrate has a binder phase gradient with the lowest binder phase content in the outermost part of the gradient surface zone and the cemented carbide having graphite. The arrangement leads to a significantly prolonged tool life.