A cutting table comprises a polycrystalline hard material and at least one rhenium-containing structure within the polycrystalline hard material and comprising greater than or equal to about 10 weight percent rhenium. A cutting element, an earth-boring tool, and method of forming a cutting element are also described.

Cutting elements for earth-boring tools may include a substrate and a polycrystalline superabrasive material secured to the substrate. The polycrystalline superabrasive material may include a first region including catalyst material in interstitial spaces among interbonded grains of the polycrystalline superabrasive material. A second region at least substantially free of catalyst material in the interstitial spaces among the interbonded grains of the polycrystalline superabrasive material may be located adjacent to the first region. An undulating boundary defined between the first region and the second region may include bumps and dimples formed by crests and troughs of a repeating pattern of concentric circles encircling a longitudinal axis of the cutting element.

Rotary drill bits may include on or more cutting element assemblies which include a cutter and a mounting system. In one embodiment, the mounting system includes a housing, a first bearing component disposed within the housing, and a second bearing component associated with the cutting element. In certain embodiments, the bearing components may comprise a table of superhard material bonded with a substrate. In one or more embodiments, the bearing components may include bearing surfaces that are arcuate. For example, the bearing surfaces may be substantially spherical (a portion of a sphere). The bearing components may be arranged to act as a radial bearing as well as a thrust bearing for the cutting element, enabling the cutting element to rotate about a longitudinal axis of the cutter, relative to the housing, while also enabling the longitudinal axis of the cutter to be displaced (change angles) relative to the housing.

Rotary drill bits may include on or more cutting element assemblies which include a cutter and a mounting system. In one embodiment, the mounting system includes a housing, a first bearing component disposed within the housing, and a second bearing component associated with the cutting element. In certain embodiments, the bearing components may comprise a table of superhard material bonded with a substrate. In one or more embodiments, the bearing components may include bearing surfaces that are arcuate. For example, the bearing surfaces may be substantially spherical (a portion of a sphere). The bearing components may be arranged to act as a radial bearing as well as a thrust bearing for the cutting element, enabling the cutting element to rotate about a longitudinal axis of the cutter, relative to the housing, while also enabling the longitudinal axis of the cutter to be displaced (change angles) relative to the housing.

A multi-indenter drill bit comprising a plurality of indenters arranged on a drilling surface of a bit face, the ratio of the total indenter area to the bit face area being defined by a parameter KPI.sub.1 (expressed as a percentage); the ratio of the average individual indenter area to the bit face area being defined by a parameter KPI.sub.2, (expressed as a percentage) and wherein the relationship between KPI.sub.1 and KPI.sub.2 is defined by an equation.

A multi-indenter drill bit comprising a plurality of indenters arranged on a drilling surface of a bit face, the ratio of the total indenter area to the bit face area being defined by a parameter KPI.sub.1 (expressed as a percentage); the ratio of the average individual indenter area to the bit face area being defined by a parameter KPI.sub.2, (expressed as a percentage) and wherein the relationship between KPI.sub.1 and KPI.sub.2 is defined by an equation.

A wellbore formation system includes a downhole cutting tool having a body and at least one cutting element. A sensor is coupled to the downhole cutting tool, and the sensor includes a transmitter configured to transmit a signal prior to wear on a portion of the downhole cutting tool reaching a first amount. The sensor ceases transmission of the signal when the wear on the portion of the downhole cutting tool reaches the first amount.

A wellbore formation system includes a downhole cutting tool having a body and at least one cutting element. A sensor is coupled to the downhole cutting tool, and the sensor includes a transmitter configured to transmit a signal prior to wear on a portion of the downhole cutting tool reaching a first amount. The sensor ceases transmission of the signal when the wear on the portion of the downhole cutting tool reaches the first amount.

A drill bit insert attached to a tip portion of a drill bit to perform drilling, includes: an insert body (1) that includes: a rear end portion buried in a bit body of the drill bit; and a tip portion protruding from a surface of the drill bit and tapered toward a tip side of the insert body, in which a surface of at least the tip portion of the insert body (1) made of polycrystalline cubic boron nitride compact (4) sintered using a catalytic metal containing Al and at least one selected from the group consisting of Co, Ni, Mn, and Fe and containing 70 vol % to 95 vol % of cubic boron nitride.

A superhard polycrystalline construction comprises a body of polycrystalline superhard material comprising a superhard phase, and a second phase dispersed in the superhard phase, the superhard phase comprising a plurality of inter-bonded superhard grains. The second phase comprises particles or grains that do not chemically react with the superhard grains, and/or do not inter-grow, and form between around 1 to 30 volume % or wt % of the body of polycrystalline superhard material.