A cutting insert for a cutting tool includes a cutting edge of PCBN or PCD formed in a corner region in a transition between a side surface and a chamfer formed in an upper side of the cutting insert. A chip breaker is formed in the chamfer inside of the cutting edge, extending between a lower chamfer portion and an upper chamfer portion. The chip breaker includes a chip breaker bottom connected to the lower chamfer portion and a chip breaker wall extending from the upper chamfer portion to the chip breaker bottom. An upper transition is formed between the upper chamfer portion and the chip breaker wall. As seen in a top view, the upper transition follows a smoothly curved path including a convex middle portion. As seen in cross-section, perpendicular to the cutting edge, the chip breaker wall and the chip breaker bottom form a smooth concave profile.

The throwaway insert includes a base and a cutting edge member. The cutting edge member includes a rake face, a flank face, a first connecting face, a second connecting face, and a first ridgeline serving as a cutting edge. The rake face includes a main surface and a first chamfer provided at an edge tip portion of the cutting edge member, the edge tip portion including an extreme tip portion of the cutting edge member. In a plan view from an upper surface of the base, the flank face, the first connecting face, and the second connecting face are located external to the base. The first chamfer is inclined relative to the main surface so as to increase a thickness of the cutting edge member as the first chamfer is closer to the main surface.

In a diamond polycrystal, a value of a ratio (a′/a) of a′ to a is less than or equal to 0.99 in a Knoop hardness test performed under a condition defined in JIS Z 2251:2009, where the a represents a length of a longer diagonal line of a first Knoop indentation formed in a surface of the diamond polycrystal when a Knoop indenter with a test load of 4.9 N is pressed onto the surface of the diamond polycrystal, and the a′ represents a length of a longer diagonal line of a second Knoop indentation remaining in the surface of the diamond polycrystal after releasing the test load.

A rotary cutting tool includes a main body and a shank. The main body has a tip end. The shank is continuous with the main body on the side opposite to the tip end. The main body is provided with a first cutting edge having a positive twist angle, and a second cutting edge having a negative twist angle and separated from the first cutting edge. Each of the first cutting edge and the second cutting edge extends continuously from the tip end to the shank.

A drill includes a blade tip part that is formed of diamond and a trunk part that is formed of diamond and is continuous with the blade tip part, the drill rotating about a drill axis, the blade tip part includes N cutting edges where N is an integer of no less than 4, and a proportion of S1 to S2 is no less than 30% and no more than 60%, where S1 is an area of the drill in a cross-section with the drill axis as a normal line, the cross-section including a boundary between the blade tip part and the trunk part, r is a maximum value of a distance from the drill axis to an outer edge of the drill in the cross-section and S2 is an area of a circle with r as a radius.

A diamond cutting tool comprises a base metal part and a diamond part joined to the base metal part, wherein the base metal part is made of an alloy containing tungsten carbide, the diamond part configures at least a cutting blade, the cutting blade comprises a portion of a rake face, a portion of a flank face, and a ridge line at which the rake face and the flank face cross, the diamond cutting tool has a region A, the region A is a region that is present bridging over the three, which are the rake face, the ridge line, and the flank face on the surface of the cutting blade, and the region A has a surface roughness Ra of not more than 0.2 μm and a concentration of tungsten element of not more than 1 mass %.

There is provided a diamond cutting tool including a cutting edge portion containing single crystal diamond or binderless polycrystalline diamond and graphite, wherein when Raman spectroscopy is performed on a surface of the cutting edge portion, a ratio R1 of Ig1 to a sum of Id1 and the Ig1 is equal to or more than 0.5 and equal to or less than 1, where the Idi represents a peak intensity of first carbon in the surface, the Ig1 represents a peak intensity of second carbon in the surface, the first carbon represents carbon that forms the single crystal diamond or the binderless polycrystalline diamond.

Cutting tools (14) and cutting tool assemblies (10) include a friction ring (79). The friction ring (79) is provided in (disposed/secured within) a retaining groove (32) of a shank (30) of the cutting tool (14). The friction ring (79) can be formed from a resilient material or materials (150). The friction ring (79) can be secured in the retaining groove (32) by a retainer ring (80). The cutting tools (14) can also include a shank (30) having an increased diameter to provide increased strength and allow for a heavier cutting portion (28) of the cutting tool (14). The cutting tools (14) and cutting tool assemblies (10) can also include a washer (100) fitted about the shank (30) and positioned adjacent to a back side (26) of the cutting portion (28) of the cutting tool (14) for stabilizing the cutting tool body (22) in relation to a cutting tool holder (12).

A sensor system has a cutter element for a cutting tool, an interrogation transceiver operable to transmit a radio-frequency (RF) interrogation signal; and a sensor transceiver system operable to receive the RF interrogation signal and to transmit an RF response signal. The sensor transceiver system includes a signal guide medium configured to transduce between the RF interrogation signal, a guided signal in the signal guide medium, and the RF response signal. A characteristic of the RF response signal is dependent upon a condition of the signal guide medium. The cutter element includes the signal guide medium to allow the condition of the signal guide medium to depend upon a condition of the cutter element proximate the signal guide medium. A method of using the sensor system is also disclosed.

A cutting element (1) for a tool with an electrically conductive track (6) formed at a surface region. The cutting element (1) comprises a HPHT produced polycrystalline diamond body. The conductive track (6) comprises graphite such that the electrically conductive track (6) has an electrical resistance substantially lower than that of the surface region.