A cutting tool holder of the present disclosure includes a bar-shaped main body. The main body includes a first pocket to receive a first insert, a second pocket to receive a second insert, a first groove extending from the first pocket, and a second groove extending from the second pocket. The first groove includes a second opening located on a rear side in a rotation direction, and the second groove includes a fourth opening located on a rear side in the rotation direction in a cross section orthogonal to a rotation axis. An angle θ1 formed by the second opening and an outer peripheral surface of the main body is smaller than an angle θ2 formed by the fourth opening and the outer peripheral surface of the main body in a cross section orthogonal to the rotation axis.

A cutting insert may include a first surface, a second surface, a third surface, and a cutting edge. The first surface may include a first side part, a second side part, and a third side part. The cutting edge may be located at an intersection of the first surface and the third surface. The cutting edge may include a first cutting edge, a second cutting edge, and a third cutting edge. The third cutting edge may be located between the first cutting edge and the second cutting edge and have a convex curvilinear shape. The first cutting edge may be located asymmetrically relative to a bisector of an angle formed by the first side part and the second side part. The first surface may include a first inclined surface located along the first cutting edge and inclined toward the second surface at a first inclination angle.

A threading insert includes a top surface, an opposite bottom surface, a side surface connecting the top surface and the bottom surface, and a first tooth. The first tooth has a first cutting edge, the first cutting edge including a first top cutting edge connecting a first leading cutting edge and a first trailing cutting edge. The first cutting edge has an edge roundness and the size of the edge roundness varies along the first cutting edge.

A physical configuration of multiple-layer coatings formed with at least one layer of coating containing cubic born nitride (cBN) particles with one or more layers in composite form containing cBN particles may have a thickness of each individual layer as thin as in the nanometer range, or as thick as in the range of a few microns and even up to tens of microns. The chemistry of the composite layer consists of any individual phase of (a) nitrides such as titanium nitride (TiN), titanium carbonitride (TiCN), and hafnium nitride (HfN); (b) carbides such as titanium carbide (TiC); and (c) oxides such as aluminum oxide (AI.sub.2O.sub.3) or any combination of the above phases, in addition to cBN particles. The coating or film can be stand-alone or on a substrate.

A tool insert includes first, second, and third teeth arranged on a surface of the tool insert. The first tooth is arranged at a proximal end of the tool insert surface and has an angled leading end and a first tooth height. The second tooth is spaced from the first tooth by a first distance along the surface of the tool insert and has a second tooth height greater than the first tooth height. The third tooth is spaced from the second tooth by a second distance along the surface of the tool insert and has an extending angled portion. The first tooth forms a first groove in a bore surface. The second tooth increases the depth of the first groove. The third tooth provides at least one micro-scratch to one of the first groove and the bore surface.

A turning insert has two opposite main surfaces and a peripheral surface which extends therebetween and has N side surfaces, where 2<N<9. The insert has mirror symmetry about a mid-plane and 360/N degree rotational symmetry about a central axis perpendicular to the mid-plane. The insert has two main edges which each have N main cutting edges and N corner cutting edges. Each main cutting edge has two raised edge portions and a lowered edge portion. Each main surface has N main rake surfaces and N corner rake surfaces. Each main surface further has at least N convex island protrusions and N at least partially convex peninsula protrusions, any and all island protrusions associated with a given main rake surface being located between two adjacent peninsula protrusions, each pair of adjacent peninsula protrusions having at least one island protrusion located therebetween.

A cutting insert is described. It has a cutting insert body with a central mounting section and at least one cutting edge. The cutting edge is wave-shaped and generally descending from an end section of the cutting edge towards a middle section of the cutting edge. Furthermore, a chip guiding recess extends substantially along the at least one cutting edge and is arranged between the cutting edge and the central mounting section. A chip breaker element is arranged in the chip guiding recess. The chip breaker element comprises a first portion having a first width and a second portion having a second width, wherein a transition between the first portion and the second portion is formed as a step.

A cutting insert may include a first surface, a second surface, a third surface, and a cutting edge. The first surface may include a first side part, a second side part, and a third side part. The cutting edge may be located at an intersection of the first surface and the third surface. The cutting edge may include a first cutting edge, a second cutting edge, and a third cutting edge. The third cutting edge may be located between the first cutting edge and the second cutting edge and have a convex curvilinear shape. The first cutting edge may be located asymmetrically relative to a bisector of an angle formed by the first side part and the second side part. The first surface may include a first inclined surface located along the first cutting edge and inclined toward the second surface at a first inclination angle.

A cutting tool has an insert holder with an indexable cutting insert removably secured therein. The cutting insert has upper and lower end surfaces with a peripheral side surface and a through bore extending therebetween, and a plurality of upper cutting edges formed on an upper peripheral edge. The peripheral side surface includes a non-circular upper relief surface adjacent the upper peripheral edge and a circular upper abutment surface spaced apart from the upper peripheral edge. Each upper cutting edge exhibits mirror symmetry about a bisector plane, and is non-linear in a side view. The through bore has an inner undercut formed by upper and lower bore surfaces located on opposite sides of a median plane, and a clamping member makes contact with one of the upper and lower bore surfaces at an inner contact zone located between the median plane and a seat surface of the insert holder.

A cutting tool holder of the present disclosure includes a bar-shaped main body. The main body includes a first pocket to receive a first insert, a second pocket to receive a second insert, a first groove extending from the first pocket, and a second groove extending from the second pocket. The first groove includes a second opening located on a rear side in a rotation direction, and the second groove includes a fourth opening located on a rear side in the rotation direction in a cross section orthogonal to a rotation axis. An angle 1 formed by the second opening and an outer peripheral surface of the main body is smaller than an angle 2 formed by the fourth opening and the outer peripheral surface of the main body in a cross section orthogonal to the rotation axis.