There is provided a cutting insert used for both drilling and turning. The cutting insert includes an insert main body having a front surface and a rear surface, the outline shapes of which are parallelogram shapes, peripheral side surfaces disposed on four sides of the insert main body, cutting edges provided on respective intersecting ridge lines between the front surface and the peripheral side surface and between the rear surface and the peripheral side surface of the insert main body, and a hole provided in the insert main body to incline with respect to the front surface and the rear surface, the hole being usable for attachment.

A drill includes a drill body having a longitudinal axis, a front end, and a frontend portion and at least one flute in the front end portion. A cutting insert is mounted to the drill body in each flute of the at least one flute at the front end of the drill body. The at least one flute includes a plurality of grooves, concave surfaces of adjacent ones of the grooves intersecting to define a ridge separating the grooves.

A cutting body for a drilling tool has a center axis, at least one cutting element with at least one cutting edge, and at least one side face. The at least one side face has at least one radially inwardly directed cutout, which is designed to produce a drilled hole having an increased roughness, the cutout having precisely three open sides.

A drill in which: a chip discharge groove is formed in an outer periphery of an edge portion serving as a leading end side portion of a drill body; and a cutting edge is formed in an intersecting edge between a rake surface of a leading end side region and a leading end flank of the edge portion, the drill comprising a margin portion, a shoulder portion and a web thinning portion, wherein: the cutting edge comprises, in order from a rotation center, a first cutting edge portion, a second cutting edge portion, a shoulder cutting edge portion, and a margin cutting edge portion; the honing width gradually decreases from the boundary P1 toward the position P2; and the conditions represented by expression (1): honing width of second cutting edge portion?R1 and expression (2): 2.0<R1/R2<5.0 are satisfied.

A drill bit for drilling a hard material includes a drill bit blade defining an axis of rotation and including a first side and a second side positioned respectively on first and second lateral sides of the axis of rotation. The drill bit blade further includes a blade tip point that is laterally biased relative to the axis of rotation, and a first blade edge and a second blade edge starting at the blade tip point and ending at the first side and second side, respectively. An angular bisector between the first and second blade edges is inclined at an angle relative to the axis of rotation.

A one-piece cutting head for a drill bit includes a main cutting edge that extends between radial extremities of the cutting head. The main cutting edge is disposed between main rake surfaces and main relief surfaces. Each main rake surface includes one or more rake facets, and each main relief surface includes one or more relief facets. Adjacent rake facets and relief facets define a primary transverse edge therebetween that extends away from the main cutting edge. The cutting head further includes a plurality of side cutters that are transverse to the main cutting edge and that propagate from the primary transverse edge to a radial extremity of the cutting head. Each side cutter includes a side cutting edge between a side cutting rake facet and a side cutting relief facet.

A drill bit includes a body having a first end, a second end, an axis of rotation defined through the first and second end, and a body flute that extends along the axis of rotation at a helix angle. The drilling tool also includes a cutting head attached to the second end of the body. The cutting head includes a first land, a second land, and a cutting head flute. The cutting head flute is defined between the first land and the second land. The cutting head flute extends along the axis of rotation at the helix angle such that the body flute and the cutting head flute form a continuous flute.

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--Si.sub.W.sub.)N where is 0.01 to 0.20 and 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 drill bit cutter and a drill bit are disclosed. The drill bit cutter defines a rotation axis and includes two cutter parts located at two sides of the rotation axis in a transverse direction, each cutter part having a front cutter face, a rear cutter face, and a blade formed between the front cutter face and the rear cutter face. The front cutter face of each cutter part is ground to form a ground shaped face. The ground shaped faces of the two front cutter faces are different, At least a local height difference is thereby produced in the two blades. Drilling precision can be increased while extending cutter life.

A drill bit is provided having a tip segment, a shaft, and an interface feature. The tip segment includes a cutting end, an attachment end, and a body. The attachment end defines an attachment surface facing in a direction away from the cutting end. A cross-sectional area perpendicular to the central axis is defined by an outer perimeter of the body. The shaft includes a first end coupled to the attachment end. The interface feature is located on the attachment surface and positioned between the attachment end and the first end. An outer surface of the interface feature and the attachment surface define an interface surface. The interface surface has a surface area greater than the cross-sectional area of the tip segment. In various embodiments, the interface feature includes at least one protrusion and/or at least one recess.