In one aspect, composite tool holders are described herein comprising advantageous structural arrangements of metal carbide and alloy components. Briefly, a composite tool holder comprises a metal carbide shank comprising a bore having an inner diameter and outer diameter. An alloy sleeve is positioned in the bore for engaging a tool, wherein the alloy sleeve is bonded to inner diameter surfaces of the bore via a crosslinked adhesive.

A rod includes a first rod section occupying a predetermined region in a longitudinal direction, and a second rod section occupying a region different from the first rod section in the longitudinal direction. The first rod section has composition including A% by mass of cobalt, 0 to 1% by mass of chromium, 0 to 0.5% by mass of vanadium, and remainder of tungsten carbide and unavoidable impurities. The second rod section has composition including B% by mass of cobalt, 0 to 1% by mass of chromium, 0 to 0.5% by mass of vanadium, and remainder of tungsten carbide and unavoidable impurities. Contents of cobalt in the first rod section and the second rod section satisfy a relationship of 1% by massB<A20% by mass. The second rod section has a length of 10 to 1000% with respect to the first rod section in the longitudinal direction.

A hole saw structure, which is cooperated with a hole saw arbor for performing a perforating operation, includes a cylindrical body and a blade set. The cylindrical body has a central chamber and includes an end surface and a peripheral wall. One end portion of the peripheral wall is connected around a circumference of the end surface, the other end portion of the peripheral wall is outwardly folded and overlapped around the peripheral wall so as to form a folded portion, the folded portion includes a folded end, and an inner diameter of the cylindrical body is smaller than an outer diameter of the folded portion. The blade set is disposed on the folded portion and includes at least two cutting teeth and at least two chip discharging notches.

A cutting tool according to one aspect of the present disclosure includes an attaching portion, a cutting portion having a core portion and a surface portion, and a joint portion. The attaching portion includes a hard component and a hard material. The hard component is at least one selected from the group consisting of TiC, TiCN, W, WC, Al.sub.2O.sub.3, and a combination of at least one of CBN and diamond and at least one of W and WC. The hard material includes one or two or more types of iron group elements, and has a Young's modulus of not more than 350 GPa. The core portion includes a cemented carbide material. The surface portion includes PCD or CBN. The cutting portion has a chamfer portion. The surface portion includes a groove, a flank face, and a cutting edge. The cutting edge extends toward the attaching portion.

A cutting tool according to one aspect of the present disclosure includes an attaching portion, a cutting portion having a core portion and a surface portion, and a joint portion. The attaching portion includes a hard component and a hard material. The hard component is at least one selected from the group consisting of TiC, TiCN, W, WC, Al.sub.2O.sub.3, and a combination of at least one of CBN and diamond and at least one of W and WC. The hard material includes one or two or more types of iron group elements, and has a Young's modulus of not more than 350 GPa. The core portion includes a cemented carbide material. The surface portion includes PCD or CBN. The cutting portion has a chamfer portion. The surface portion includes a groove, a flank face, and a cutting edge. The cutting edge extends toward the attaching portion.

A rod, a cutting tool and a method for manufacturing a cutting tool are disclosed. In an embodiment, the rod may include a cemented carbide member containing WC and Co. The cemented carbide member may be elongated and include a first end portion and a second end portion in a longitudinal direction. The first end portion may have a Co content Co.sub.AC smaller than a Co content Co.sub.BC of the second end portion. The cemented carbide member may include a first portion on a side of the first end portion and a second portion on a side of the second end portion. The first portion may have a gradient S.sub.1 representing a change in a Co content per milliliter. The second portion may have a gradient S.sub.2 representing a change in a Co content per milliliter. The gradient S.sub.1 may be greater than the gradient S.sub.2.

A cutter holder has a body, a fastening bolt, and a vibration absorbing structure. The body has a specific weight. The fastening bolt is mounted inside the body. The vibration absorbing structure is mounted inside the body and has a sleeve, an elastic unit, a spacer, and a set nut. The sleeve is mounted around the fastening bolt and has a specific weight. The specific weight of the sleeve is larger than the specific weight of the body. The elastic unit is mounted around the fastening bolt and has two opposite ends. One of the ends of the elastic unit abuts against the sleeve. The spacer is mounted around the fastening bolt and abuts against the other end of the elastic unit. The set nut is screwed with the fastening bolt and abuts against the spacer.

Provided is a coated cutting tool in which a surface of a substrate is coated with a hard coating film. The hard coating film includes: a layer (A) disposed on the surface of the substrate, and having a face-centered cubic lattice structure, in which the total content ratio of W and Ti is at least 85 atomic %, and which contains W as the most abundant element and Ti as the next most abundant element among metal (including metalloid) elements; and a layer (B) disposed on the layer (A) and having a face-centered cubic lattice structure, which is composed of nitrides or carbonitrides containing Al, Cr, and Si, and in which, among metal (including metalloid) elements, the Al content ratio is at least 50 atomic %, the total content ratio of Al and Cr is at least 85 atomic %, and the Si content ratio is 4 to 15 atomic %.

In a surface-coated cutting tool, a hard coating includes one or more layers. At least one layer thereof is a hard coating layer composed of a complex nitride or carbonitride layer of Al, Cr, and Si and satisfying (Al.sub.1-x-yCr.sub.xSi.sub.y)(C.sub.zN.sub.1-z) where x, y and z are atomic ratios and satisfy 0.1x0.4, 0.01y0.2, and 0z0.3, respectively. The hard coating layer contains particles including: less than 10 atomic % of non-metal components selected from C and N; and metal components selected from Cr, Al and Si. In the cross-section perpendicular to the tool body surface, the number ratio of oblate particles with an Al content of 50 atomic % or less, a long diameter of less than 0.5 m, and an aspect ratio of 2.0 or more is 90% or more with respect to the total number of the particles.

A cutter holder has a body and a buffering assembly. The body has a specific weight. The buffering assembly is mounted in the body and has a buffering unit and an elastic unit set. The buffering unit has a specific weight that is larger than the specific weight of the body. The buffering unit and the elastic unit set are utilized for absorbing vibration. The elastic unit set has multiple Belleville washers and can be changed in scales or amounts according to practical machining conditions.