A cutting insert according to one aspect has a flat plate shape including a first main surface having a polygonal shape, a second main surface located opposite to the first main surface, and an outer peripheral surface located between the first main surface and the second main surface. The cutting insert includes a cutting portion located in regions including at least a corner portion of the first main surface, and a main body portion located in a region other than the corner portion. A thickness of the main body portion is larger than a thickness of the cutting portions, and the main body portion includes a recessed portion or a protruding portion located in the outer peripheral surface thereof.

Provided is a holder of a cutting insert that performs turning on a work by feeding a cutting edge in a Y axis direction which is different from a longitudinal direction (X axis) of a tool holder installed in a tool rest, and that can easily adjust the projection amount without contacting a part of the holder to the tool rest. A Y axis holder holds the cutting insert including a cutting edge to perform turning on a work that moves along the Z axis, and is installed in a state where relative movement in the X axis direction with respect to the tool rest is possible, such that a projection amount of the cutting insert along the X axis is changeable. The Y axis holder performs turning on the work using the cutting insert when the holder moves in the Y axis direction which is different from the X axis direction. The Y axis holder has a shape in which an end portion thereof in the X axis direction is projected from the cutting edge of the cutting insert, and a positioning portion to determine the projection amount of the cutting insert from the tool rest is disposed on the end portion.

An indexable parting blade has opposite blade first and second sides, a blade peripheral edge, a central index axis, and at least first, second and third insert pockets located along the blade peripheral edge. The parting blade also has first, second and third coolant channels, each forming a coolant path from a corresponding inlet to a corresponding one of the insert pockets. Each coolant channel includes a rake outlet opening out to a rake side of its corresponding insert pocket and a relief outlet opening out to a relief side of that same insert pocket. The inlet corresponding to a given coolant channel is located further from that coolant channel's insert pocket than at least one of (a) the inlet corresponding to a different coolant channel, and (b) the central index axis.

A shank for a tool bit employing an offset arrangement is provided, the shank being able to respond to various types of machining through replacement of heads and having a structure to save time and steps necessary for such replacement of the heads. A cutting tool having such shank is also provided.

A shank 53 of a head-replaceable cutting tool has at least one head attaching part 53A, 53B that is arranged off-center relative to an axis 53X of the shank 53. The axis 53X of the shank 53 corresponds to an axis extending in a longitudinal direction of the shank 53, and the head attaching part 53A, 53B may be arranged so as to be off-center in a direction perpendicular to the axis 53X.

A method for cutting a groove of a predetermined groove width in a work piece, including the steps of providing a metallic work piece having a peripheral surface; providing a grooving tool including a blade portion having a constant or substantially constant blade width, and an insert having a maximum insert width defined by a main cutting edge; selecting the insert width to be greater than the blade width; connecting the grooving tool to a machine interface of a machine tool; rotating the work piece about a rotational axis thereof in a rotational direction; and cutting a groove in the work piece by moving the tool in a feed direction towards the rotational axis of the work piece, such that the groove width is equal to or substantially equal to the insert width and such that a tangential cutting force is directed towards or substantially towards the machine interface.

Cutting tool holders are disclosed that include vibration dampening elements. The vibration dampening elements may extend parallel to a longitudinal plane of the cutting tool holder. The vibration dampening elements allow the cutting tool holders to have a smaller width while still providing higher grooving depth.

A cutting insert includes a cylindrical body portion, a cutting portion, a first fitting portion, a second fitting portion, and a third fitting portion. The cutting portion includes a rake face and a flank face. A ridgeline between the rake face and the flank face constitutes a cutting edge. When viewed in the axial direction, the cutting portion is provided opposite to the third fitting portion relative to the insertion hole. When viewed in the axial direction, a straight line extending through an outer circumferential end of the cutting edge and a center of the insertion hole overlaps with the third fitting portion and is located between the first fitting portion and the second fitting portion. A third central angle is smaller than a first central angle and is smaller than a second central angle.

An indexable cutting insert has a central mounting portion and two cutting portions. The central mounting portion has opposing upper and lower surfaces. The lower surface has two abutment elements associated therewith, each abutment element having two diverging abutment surfaces forming two abutment angles. The two cutting portions extend away from the central mounting portion, have distal cutting edges, and are entirely located in diagonally opposite imaginary quadrants of four quadrants defined by two mutually perpendicular quadrant planes. Two abutment bisector planes bisecting the two abutment angles and one of the quadrant planes are parallel or coincident. In a top view, the two cutting portions extend away from the central mounting portion in opposite directions. Two cutting bisector lines parallel to the two directions and bisecting the two cutting edges are mutually offset. A cutting tool has an insert holder and the cutting insert removably retained therein.

A cutting tool assembly having a longitudinal axis establishing upward and downward directions, includes a Y-axis parting adaptor mounted onto a holder. The parting adaptor has an insert pocket including a base jaw configured to support a cutting insert. The holder has a holder head portion and a shank portion. The holder head portion has an adaptor pocket in which the parting adaptor is mounted. If the holder shank cross-sectional shape is square or rectangular the forwardmost cutting edge is directly above the forwardmost holder shank surface, and if the holder shank cross-sectional shape is round and a centrally extending holder shank axis extends to the forwardmost cutting edge.

To provide a cutting insert such that a tool body can sufficiently hold the cutting insert even if one of cutting parts is broken. The cutting insert includes two side surfaces opposed to each other, a fixing hole passing through the centers of the two side surfaces, and an outer circumferential surface that is disposed between the outer circumferential edges of the two side surfaces and are connected to the outer circumferential edges of the two side surfaces. The outer circumferential surface includes four cutting parts, a first outer circumferential surface part that is disposed between the first cutting part and the second cutting part, and a second outer circumferential surface part that is opposed to the first outer circumferential surface part and is disposed between the third cutting part and the fourth cutting part. In a side view of the side surfaces from the axial direction of the fixing hole, the first outer circumferential surface part and the second outer circumferential surface part each have the center recessed toward the fixing hole, and a virtual arc having the same diameter as the diameter of the circumcircle of the cutting insert is in contact with two points on each of the outer circumferential surface parts.