A cutting insert comprises: a body; and a blade fixed to the body and made of a polycrystalline cubic boron nitride including 98.5% by volume or more of cubic boron nitride, the blade having a rake face and a flank face, the rake face and the flank face meeting each other and thus forming a ridge line which serves as a cutting edge, the rake face being provided with a land surface extending along the cutting edge, and a chip breaker disposed on a side opposite to the cutting edge with the land surface therebetween and also having a recess contiguous to the land surface.

A rotary cutting tool is provided that includes a cutter body, and a plurality of cartridges, fasteners, and cartridge axial adjustment mechanisms. The cutter body has a rotational axis, a circumferential exterior surface, and a plurality of cartridge pockets disposed in the circumferential exterior surface. A cartridge fastener threaded aperture is disposed in each cartridge pocket. The cartridge fastener threaded apertures extend along an axis disposed at an acute angle. Each cartridge has a body having at least one cartridge fastener aperture disposed at the acute angle. Each cartridge axial adjustment mechanism is aligned with a cartridge. Each fastener holds a cartridge against a cartridge pocket, and biases the cartridge against the aligned cartridge axial adjustment mechanism.

A face milling tool includes a tool body having an axial front end surface with several seats. Each seat has support surfaces for rotationally locking and supporting a tangential cutting insert in the seat. One of the support surfaces is a flat axial support surface for supporting the tangential cutting insert in an axial direction defined by the central rotation axis. The flat axial support surface extends perpendicular to the central rotation axis and is situated axially foremost in the seat. A side wall of each seat is formed out of round side support surfaces. Each tangential cutting insert includes an axial back side with a flat axial contact surface abutting the flat axial support surface and a projecting member extending axially from the flat axial contact surface and having a circumferential side surface forming out of round side contact surfaces abutting the out of round side support surfaces.

Holders are described herein providing secure clamping and/or positioning of cutting inserts. Briefly, a holder for a cutting insert comprises a base and a slot for receiving the cutting insert, wherein the slot forms an angle with the base ranging from 10 degrees to 60 degrees.

An end mill has a shank and a cutting edge main body portion. The cutting edge main body portion is provided on the shank and has a coolant supply path. The cutting edge main body portion includes a trailing end surface on a side of the shank, and a leading end surface opposite to the trailing end surface. The coolant supply path has a tapered portion which widens in a direction from the trailing end surface toward the leading end surface.

Provided is a surface-coated cutting tool including: a tool body (3) and a hard coating layer on the tool body (3). The hard coating layer has an alternate laminate structure of A (1) and B layers (2). The A layer (1) is a Ti and Al complex nitride layer satisfying a compositional formula: (Ti.sub.1-zAl.sub.z)N, 0.4z0.7. The B layer (2) is a Cr, Al and M complex nitride layer satisfying a compositional formula: (Cr.sub.1-x-yAl.sub.xM.sub.y)N, 0.03x0.4 and 0y0.05. The value of a ratio tB/tA of the average layer thickness of the B layer (2) to the average layer thickness of the A layer (1) satisfies 0.67 to 2.0. The lattice constant a() of crystal grains of the hard coating layer satisfies 4.10a4.20. The ratio of I(200) to I(111) satisfies 2.0I(200)/I(111)10.

A coated cutting tool comprising a substrate comprising a cubic boron nitride sintered body and a coating layer formed on the substrate, wherein the coating layer comprises a Ti carbonitride layer comprising Ti(C.sub.xN.sub.1-x); an average thickness of the Ti carbonitride layer is 0.5 m or more and 5.0 m or less; in the Ti carbonitride layer, R75 is higher than R25; in the Ti carbonitride layer, a texture coefficient TC (111) of a (111) plane is 1.0 or more and 2.0 or less; and in X-ray diffraction measurement of the Ti carbonitride layer, an absolute value of a difference between a maximum value and a minimum value of 2 is 0.1 or less on the (111) plane when the measurement is performed at each of angles of 0, 30, 50 and 70.

A milling tool includes: a body having an outer circumferential surface formed around a central axis; a cutting insert having a rake surface, a flank surface, and a cutting edge formed by a ridgeline of the rake surface and the flank surface; and a screw attaching the cutting insert to the body. The outer circumferential surface has an insert attachment portion. The insert attachment portion is defined by a first seat surface continuing to the outer circumferential surface and a second seat surface continuing to the first seat surface and having a flat portion provided with a screw hole in which the screw is inserted. The cutting edge is formed of a sintered material containing at least one of cubic boron nitride and polycrystalline diamond. In a cross section perpendicular to the central axis, a first angle formed by a first direction and a second direction is an acute angle.

A mirror finishing method for mirror-finishing a workpiece includes: a step of performing a first machining operation with a first tool which has a cylindrical portion made of polycrystalline diamond or cubic boron nitride at the tip of a shank thereof and further has a cutting edge formed by forming a linear groove on the cylindrical portion; and a step of, after the first machining operation has been performed, performing a second machining operation with a second tool which has a cylindrical portion made of polycrystalline diamond or cubic boron nitride at the tip of a shank thereof with no cutting edge on the cylindrical portion.

A cutting insert may include a base body, a first part and a second part. The base body may include a first surface, a second surface, a first lateral surface, a second lateral surface, a first recess and a second recess. The first part may be located in the first recess. The second part may be located in the second recess. The first recess may include a first bottom surface, a first wall surface and a first valley line located on an intersection of the first bottom surface and the first wall surface. The second recess may include a second bottom surface, a second wall surface and a second valley line located on an intersection of the second bottom surface and the second wall surface. The first valley line may intersect with the second valley line in a perspective view of the first surface.