A hob for a cutting apparatus including a hollow body of a sintered hard metal composition and a cavity located within the body, the cavity having a volume in the range of about 10% to about 90% of the volume of the body.

A cutting tool body includes a first member and a second member, both having a substantially cylindrical shape, and arranged such that a tool body central axis coincides with a central axis of each of the first and the second members. The first member has a tool characteristic of a first magnitude and the second member has the tool characteristic of a second magnitude, different from the first magnitude. The cutting tool body includes a transition member arranged between the first and second members and connected at a first end to the first member and at a second end to the second member. The tool characteristic in the transition member is of the first magnitude at the first end and of the second magnitude at the second end. The transition member has a transition region between the first and the second ends in which the tool characteristic transforms from the first magnitude to the second magnitude.

A three-dimensional shaping method including the steps, after a lamination step, in which steps of forming a powder layer, flattening with a squeegee and sintering are repeated, followed by cutting of the surface of the laminate, 1. setting the overall shape of an object to be shaped by a CAD/CAM system, and setting machining units that form the overall shape and cutting allowances on peripheral sides and upper sides of each of the machining units, 2. cutting of the peripheral sides and upper sides according to a prescribed order, after lamination with addition of a cutting allowance on the peripheral sides of each machining unit, and after carrying out lamination to the thickness of the cutting allowance on the upper side of the machining unit and the machining unit adjacent above the machining unit, and 3. continuing repetition of step 2, from the lowest to the topmost machining unit.

A rotary cutting tool, which is excellent in defect resistance and has a stable lifespan, includes a rake surface composed of one surface, a cutting edge angle that is larger than 0? and smaller than 90?, a true rake angle that is not smaller than ?42? and not larger than ?13?, and a major cutting edge inclination angle that is not smaller than ?5? and smaller than +5?. A wiper insert is preferably formed in a rounded convex shape.

A sintered body of the present invention is a sintered body including a first material and cubic boron nitride. The first material is partially-stabilized ZrO.sub.2 including 5 to 90 volume % of Al.sub.2O.sub.3 dispersed in crystal grain boundaries or crystal grains of partially-stabilized ZrO.sub.2.

A sintered compact has a first material, a second material, and a third material. The first material is cubic boron nitride. The second material is a compound including zirconium. The third material is an aluminum oxide and the aluminum oxide includes a fine-particle aluminum oxide. The sintered compact has a first region in which not less than 5 volume % and not more than 50 volume % of the fine-particle aluminum oxide is dispersed in the second material. On arbitrary straight lines in the first region, an average value of continuous distances occupied by the fine-particle aluminum oxide is not more than 0.08 m and a standard deviation of the continuous distances occupied by the fine-particle aluminum oxide is not more than 0.1 m.

A sintered compact according to the present invention includes: a first material that is cubic boron nitride; a second material that is an oxide of zirconium; and a third material that is an oxide of aluminum, the second material including cubic ZrO.sub.2 and ZrO, the third material including -Al.sub.2O.sub.3, and the sintered compact satisfying the following relation:
0.9I.sub.zro2(111)/I.sub.al(110)30; and
0.3I.sub.zro(111)/I.sub.al(110)3, where I.sub.al(110), I.sub.zro2(111), and I.sub.zro(111) respectively represent X-ray diffraction intensities of a (110) plane of the -Al.sub.2O.sub.3, a (111) plane of the cubic ZrO.sub.2, and a (111) plane of the ZrO.

A sintered compact according to the present invention includes: a first material that is cubic boron nitride; a second material that is an oxide of zirconium; and a third material that is an oxide of aluminum, the second material including cubic ZrO.sub.2 and ZrO, the third material including -Al.sub.2O.sub.3, and the sintered compact satisfying the following relation:

0.9I.sub.zro2(111)/I.sub.al(110)30; and

0.3I.sub.zro(111)/I.sub.al(110)3,

where I.sub.al(110), I.sub.zro2(111), and I.sub.zro(111) respectively represent X-ray diffraction intensities of a (110) plane of the -Al.sub.2O.sub.3, a (111) plane of the cubic ZrO.sub.2, and a (111) plane of the ZrO.

A sintered compact has a first material, a second material, and a third material. The first material is cubic boron nitride. The second material is a compound including zirconium. The third material is an aluminum oxide and the aluminum oxide includes a fine-particle aluminum oxide. The sintered compact has a first region in which not less than 5 volume % and not more than 50 volume % of the fine-particle aluminum oxide is dispersed in the second material. On arbitrary straight lines in the first region, an average value of continuous distances occupied by the fine-particle aluminum oxide is not more than 0.08 m and a standard deviation of the continuous distances occupied by the fine-particle aluminum oxide is not more than 0.1 m.

A cubic boron nitride sintered material tool contains a plurality of cBN grains. cBN grains located on a surface of the cutting edge contain a cubic boron nitride phase, and a hexagonal boron nitride phase. When a ratio I.sub.*/I.sub.* between an intensity of a * peak derived from a bond of hBN in the hexagonal boron nitride phase and an intensity of a * peak derived from a bond of hBN in the hexagonal boron nitride phase and a bond of cBN in the cubic boron nitride phase is determined by measuring an energy loss associated with excitation of K-shell electrons of boron, the ratio I.sub.*/I.sub.* of the cBN grain on the surface of the cutting edge is 0.1 to 2, and the ratio I.sub.*/I.sub.* of the cBN grain at a depth position of 5 m from the surface of the cutting edge is 0.001 to 0.1.