A method for machining ribs or grooves on a workpiece such as a shaft or an air or gas axial bearing intended to be rotated about a longitudinal axis of a centrifugal compressor. All of the ribs or grooves are obtained at once by the machining tool on a workpiece portion driven such that it rotates, by moving the workpiece or the tool holder in a longitudinal machining direction, the machining tool moving back and forth with a machining position in contact with the workpiece and a position wherein it is not in contact with the workpiece from the start to the end of the workpiece portion. The back-and-forth movements of the machining tool are synchronised with the sinusoidal program set up in the machining unit, as well as with the desired, programmed arrangement of the ribs or grooves to be produced on the workpiece portion.

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 long twist drill includes a shank and a drill body having a drill tip (16). The twist drill has a length L and an outer diameter D, and has a cemented carbide or high speed steel substrate and a coating of at least one layer. The quota L/D is at least 16. The twist drill has two cutting segments at the tip and two flutes chip. The twist drill is provided with holes for fluid opening in the tip. The twist drill has an axial web thinning angle GAA, which is 40 to 50°. The twist drill further has a web that back tapers such that a web diameter gets smaller in a direction away from the tip towards the shank within an axial distance.

A cutting tool includes: a base metal provided with a seat portion; a blade edge member that is a polycrystalline diamond sintered material containing polycrystalline diamond and a binder; and a brazing material that fixes the blade edge member to the seat portion of the base metal. The blade edge member has a thickness of greater than or equal to 0.3 mm. The brazing material is disposed between a blade edge bottom face of the blade edge member and the a seat bottom face of the seat portion and is in contact with the blade edge bottom face and the seat bottom face. The flank face is located outside of the base metal with respect to the lateral face of the base metal.

A cutting tool rotates about a rotation axis, and includes a tip end portion. The tip end portion includes a partially spherical surface that is brought into contact with a workpiece. The surface is provided with a plurality of recesses disposed apart from each other. An opening edge of each of the plurality of recesses constitutes a cutting edge.

A composite sintered body cutting tool is made of a composite sintered body comprising a TiCN-based cermet layer; and a WC-based cemented carbide layer. The angle between the rake face and the flank face of the cutting tool is 90°. The rake face including a cutting edge of the cutting tool is constituted from the WC-based cemented carbide layer, in which 4 to 17 mass % of an iron group metal component and 75 mass % or more of W are included; and a major hard phase component is WC. The thickness of the WC-based cemented carbide layer is 0.05 to 0.3 times the thickness of the composite sintered body. The TiCN-based cermet layer is constituted from a single layer of a TiCN-based cermet layer, including at least, 4 to 25 mass % of an iron group metal component, less than 15 mass % of W, 2 to 15 mass % of Mo, 2 to 10 mass % of Nb and 0.2 to 2 mass % of Cr in a case where contents of the constituting components of the cermet layer are expressed as contents of metal components, and satisfy the Co content relative to the total content of Co and Ni of 0.5 to 0.8 with respect to Co and Ni of the iron group metal component in a mass ratio. When the height profile from the upper end to the lower end of the flank face is measured in the plane, which passes the center of the rake face of the cutting tool and is perpendicular to both of the rake face and the flank face, as the line, which passes the ridge line where the rake face and the flank face intersect and perpendicular to the rake face, being the reference line, the maximum elevation difference value of the height profile is in a ratio of 0.01 or less with respect to the thickness of the composite sintered body from the front surface of the rake face to a rear surface.

The present invention relates to a method of making a cemented carbide comprising mixing in a slurry a first powder fraction and a second powder fraction, subjecting the slurry to milling, drying, pressing and sintering. The first powder fraction is made from cemented carbide scrap recycled using the Zn recovery process, comprising the elements W, C, Co, and at least one or more of Ta, Ti, Nb, Cr, Zr, Hf and Mo, and the second powder fraction comprising virgin raw materials of WC and possibly carbides and/or carbonitrides of one or more of Cr, Zr, W, Ta, Ti, Hf and Nb. The first powder fraction is subjected to a pre-milling step, prior to the step of forming the slurry, to obtain an average grain size of between 0.2 to 1.5 μm.

In a surface-coated cutting tool in which a hard coating layer having a total layer thickness of 0.5 to 10 μm is deposited on a surface of a tool body made of WC-based cemented carbide or TiCN-based cermet, the hard coating layer has an alternately laminated structure of A layers and B layers, in a case where the A layer is: (Al.sub.aTi.sub.1-a)N (here, a is in atomic ratio), the A layer satisfies 0.50≦a<0.75, in a case where the B layer is: (Al.sub.bTi.sub.1-b)N (here, b is in atomic ratio), the B layer satisfies 0.75≦b≦0.95, and when a layer thickness per layer of the A layers is represented by x (nm) and a layer thickness per layer of the B layers is represented by y (nm), 5y≧x≧3y and 250 (nm)≧x+y≧100 (nm) are satisfied.

A surface-coated cutting tool has a hard coating layer on a tool body. The hard coating layer includes a (Ti.sub.1−xAl.sub.x)(C.sub.yN.sub.1−y) layer (the average amount Xavg of Al and the average amount Yavg of C satisfy 0.60≦Xavg≦0.95 and 0≦Yavg≦0.005). Crystal grains having an NaCl type face-centered cubic structure in the layer have {111} orientation, a columnar structure in which the average grain width of the individual crystal grains having an NaCl type face-centered cubic structure is 0.1 μm to 2.0 μm and the average aspect ratio is 2 to 10 is included, and in the individual crystal grains having an NaCl type face-centered cubic structure, a periodic compositional variation in Ti and Al in the composition formula: (Ti.sub.1−xAl.sub.x)(C.sub.yN.sub.1−y) is present and the difference between the average of maximum values of x and the average of minimum values thereof is 0.03 to 0.25.

Provided is a coated tool in which a hard coating layer has excellent hardness and toughness and exhibits chipping resistance and defect resistance during long-term use. The hard coating layer includes at least a layer of a complex nitride or complex carbonitride expressed by the composition formula: (Ti.sub.1-x-yAl.sub.xMe.sub.y) (C.sub.zN.sub.1-x) (here, Me is one element selected from among Si, Zr, B, V, and Cr), an average amount Xavg of Al, an average amount Yavg of Me, and an average amount Zavg of C satisfy 0.60≦Xavg, 0.005≦Yavg≦0.10, 0≦Zavg≦0.005, and 0.605≦Xavg+Yavg≦0.95, crystal grains having a cubic structure are present in crystal grains constituting the layer of a complex nitride or complex carbonitride, and in the crystal grains having a cubic structure, a predetermined periodic concentration variation of Ti, Al, and Me is present, whereby the problems are solved.