The present invention relates to a multi-material rotary cutting tool (1) and a method for manufacturing such a tool that includes at least one continuous or substantially continuous cutting edge (8, 9) made of at least two different successive materials. The extremity or top (10) of the tool is a point off-centered in relation to the axis of rotation (5) of the tool.

To prevent a lowering of gripping force due to temperature changes, provided is a gripping mechanism including a plurality of chuck claws that, when having come close to each other, generate a gripping force on a gripped body; a chuck body that holds the plurality of chuck claws on a common planar surface, and moves them on the planar surface; and a plurality of chuck plates that, when each of the plurality of chuck claws grips the gripped body, are interposed between each of the plurality of chuck claws and the gripped body. A thermal expansion coefficient .sub.1 of the plurality of chuck claws, a thermal expansion coefficient .sub.2 of the plurality of chuck plates and a thermal expansion coefficient .sub.W of the gripped body have a relationship indicated by
.sub.W<.sub.1<.sub.2(Equation 1).

Provided is a diamond coating cutting tool in which the adhesiveness of a diamond layer to a base material is high.

A diamond coating cutting tool 1 includes a base material 3 made of a silicon nitride sintered body or a sialon sintered body, and a diamond layer 7 coated on a surface of the base material 3. In the base material 3, an average thermal expansion coefficient x at 25? C. to 600? C. satisfies 2.6?10.sup.?6/K?x?4.0?10.sup.?6/K, and the diamond layer 7 has a compressive residual stress of 50 MPa or more and 1800 MPa or less.

A coated cutting tool and a hard and wear resistant coating for a body include at least one metal based nitride layer. The layer is (ZrxCrl-x-y-zAlyMez)Na with 0.55<x<0.85, 0.05<y<0.45, 0z<0.20, 0.95<a<1.10, and Me is one or more of the elements: Y, Ti, V, Nb, Ta, Mo, W, Mn or Si. The layer can have a thickness between 0.5 m and 15 m and be comprisied of a single cubic phase or a single hexagonal phase or a mixture thereof. In an exemplary embodiment, the layer is a cubic phase of a sodium chloride structure. The layer can be deposited using cathodic arc evaporation and is useful for metal cutting applications generating high temperatures.

A ceramic material includes of -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.

A coated cutting tool includes a substrate and a coating layer formed onto the surface of the substrate. The coating layer contains an -type aluminum oxide layer. A residual stress value at the (116) plane of the -type aluminum oxide layer is greater than 0. A residual stress value at the (012) plane of the -type aluminum oxide layer is smaller than 0.

A coated cutting tool for chip forming machining of metals includes a substrate having a surface coated with a chemical vapour deposition (CVD) coating. The coating has a layer of -Al.sub.2O.sub.3, wherein the -Al.sub.2O.sub.3 layer exhibits a texture coefficient TC(0 0 12)7.2 and wherein the ratio of I(0 0 12)/I(0 1 14) is 1.

A coated cutting tool includes a substrate and a coating having at least one ?-type aluminum oxide layer. In a cross-section of the ?-type aluminum oxide layer, when an angle formed by a normal to the cross-sectional surface and a normal to a (222) plane of a particle of the ?-type aluminum oxide layer is regarded as a misorientation, and when areas of particles, each of which has a misorientation ranging from 0-90 degrees, of the ?-type aluminum oxide layer are defined as constituting 100 area %, and the areas of particles, each of which has a misorientation ranging from 0-90 degrees, of the ?-type aluminum oxide layer are divided into respective 10-degree pitches, a total Sa of the areas of particles having a misorientation ranging from 20-30 degrees, of the ?-type aluminum oxide layer is at a maximum from among totals of areas for nine divisions in respective 10-degree pitches.

A method for producing a ceramic honeycomb body having large numbers of longitudinal cells partitioned by cell walls, with its peripheral portion removed by machining, includes rotatably holding the ceramic honeycomb body on a main axis of a lathe, and rotating the ceramic honeycomb body around the main axis, to remove its peripheral portion by machining with a tool; the lathe comprising a first fixing jig on the main axis, and a second fixing jig substantially opposing the first fixing jig; each of the first and second fixing jigs having an abutting end portion opposing each other, the abutting end portion having a smaller outer shape than that of the end surface of the ceramic honeycomb body, and the abutting portion having a substantially flat abutting end surface perpendicular to the main axis.

The present invention relates to the field of new materials technology, in particular to carbon nitride composite ceramic tool materials, preparation method and cutting tools thereof. The raw materials comprise carbon nitride, titanium carbonitride, molybdenum, nickel and cobalt, carbon nitride as the matrix phase, titanium carbonitride as the reinforcing phase are added to the carbon nitride based composite ceramic materials, with molybdenum, nickel and cobalt as a suitable sintering aid, dense composite tool material is obtained with vacuum hot press sintering method. The prepared carbon nitride based composite ceramic tool materials boast the advantages of low cost, high hardness, high bending strength and high fracture toughness, which is an important way to promote the innovation, development and popularization of carbon nitride materials.