A hard film formed on/above a substrate has a composition represented by the following formula (1): Cr.sub.1−aMg.sub.a(B.sub.xC.sub.yN.sub.1−x−y) (1). In the formula (1), a is the atomic ratio of Mg, x is the atomic ratio of B, and y is the atomic ratio of C; and a, x, and y satisfy the following relationships: 0.05≦a≦0.30, 0≦x≦0.20, and 0≦y≦0.30.

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 %.

A method for machining a workpiece is provided, wherein drilling of the workpiece and subsequent countersinking of the bore, obtained by the drilling, in the workpiece are performed by means of a drilling/countersinking tool in a machining process, wherein the drilling/countersinking tool in the machining process while being axially rotated is subjected to an axial feed movement relative to the workpiece that reaches a counterbore terminal position, and wherein the axial feed movement is superimposed by an axial vibration, wherein, when reaching a predefined frequency lowering position of the axial feed movement by the drilling/countersinking tool, the frequency of the axial vibration is lowered to a final machining frequency, and the machining process is continued at the final machining frequency as the maximum frequency of the axial vibration until the counterbore terminal position is reached.

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 cemented carbide may include a hard phase including W and C, and a binder phase including cubic Co. The binder phase may include Zr. The Co may include a lattice constant of more than 3.5575 Å and not more than 3.5600 Å. A coated tool may include a coating layer located on a surface of the cemented carbide. A cutting tool may include a holder that is extended from a first end toward a second end and may include a pocket on a side of the first end, and the coated tool located in the pocket.

The disclosure relates to a method of manufacturing a cutting tool including the steps of: providing a cutting tool blank including a cutting edge, defined by a cross-sectional wedge angle (β). The wedge angle has a variation along the cutting edge, and material is removed from the cutting edge with a constant material removal rate per length unit of the edge, such as to form a corresponding variation of edge rounding along the cutting edge. The disclosure further relates to a cutting tool including the cutting edge defined by the cross-sectional wedge angle having a variation along the cutting edge and wherein the cutting edge has a corresponding variation of edge rounding along the cutting edge.

A cutting tool comprises a substrate and a coating layer provided on the substrate, the coating layer including a multilayer structure layer composed of a first unit layer and a second unit layer, and a lone layer, the lone layer including cubic Ti.sub.zAl.sub.1-zN crystal grains, an atomic ratio z of Ti in the Ti.sub.zAl.sub.1-zN being 0.4 or more and less than 0.55, the lone layer having a thickness with an average value of 2.5 nm or more and 10 nm or less, the multilayer structure layer having a thickness with an average value of 40 nm or more and 95 nm or less, one multilayer structure layer and one lone layer forming a repetitive unit having a thickness with an average value of 50 nm to 100 nm, a maximum value of 90 nm to 110 nm, and a minimum value of 40 nm to 60 nm.

A surface-coated cutting tool with a hard coating layer exhibits excellent chipping resistance and wear resistance in a high-speed cutting process. The surface-coated cutting tool comprises a lower layer consisting of a titanium compound layer and an upper layer consisting of an aluminum oxide layer deposited on a surface of a tool substrate constituted of a tungsten carbide-based cemented carbide as a hard coating layer. In the upper layer, a (006) plane texture coefficient TC(006) is 1.8 or more, a ratio I(104)/I(110) of a peak intensity I(104) of an (104) plane to a peak intensity I(110) of an (110) plane is in a range of 0.5 to 2.0, and furthermore, an absolute value of a residual stress in the aluminum oxide layer is 100 MPa or less.

Provided is a cutting tool including a base material and a coating layer provided on the base material, the coating layer including a titanium carbonitride layer provided on the base material, an intermediate layer provided on the titanium carbonitride layer in contact therewith, and an alumina layer provided on the intermediate layer in contact therewith, the intermediate layer being composed of a compound made of titanium, carbon, oxygen, and nitrogen, the intermediate layer having a thickness of more than 1 μm, when P.sub.N1 atomic % represents an atomic ratio of the nitrogen in an interface between the intermediate layer and the alumina layer, and P.sub.N2 atomic % represents an atomic ratio of the nitrogen at a point A away from the interface by 1 μm on a side of the intermediate layer, a ratio P.sub.N1/P.sub.N2 of the P.sub.N1 to the P.sub.N2 being more than or equal to 1.03.

A turning insert includes a top surface, an opposite bottom surface and a reference plane located parallel to and between the top surface and the bottom surface. A nose portion has a convex nose cutting edge, a first cutting edge and a second cutting edge. The nose cutting edge connects the first and second cutting edges. The first and second cutting edges form a nose angle (α) of 71-85° relative to each other. The nose portion includes a third convex cutting edge adjacent to the first cutting edge and a fourth cutting edge adjacent to the third convex cutting edge. The fourth cutting edge forms an angle (β) of 10-30° relative to a bisector. The distance from at least a portion of the fourth cutting edge to the reference plane increases as the distance from the nose cutting edge increases.