Abstract: A cutting element has a substrate and a body of superhard polycrystalline material bonded to the substrate. The body of superhard polycrystalline material has a working surface, a plurality of spaced apart cutting edges, a chamfer extending from the cutting edges to the working surface, and a recessed region extending into the working surface towards the interface with the substrate and about the longitudinal axis of the body. The cutting edges are spaced around the working surface and separated by a respective further region; the radius of curvature of one or more of the cutting edges being less than the radius of curvature of the substrate. The chamfer extends from the cutting edges to the working surface and is non-variable in one or both of angle relative to the plane extending through the longitudinal axis, and length. The recessed region does not intersect and/or does not interfere with the chamfer.

Abstract: A cutter element for an earth-boring tool, comprising a polycrystalline diamond (PCD) volume joined at an interface boundary to a cemented carbide substrate. The PCD volume includes a rake face opposite the interface boundary, an edge of the rake face being suitable as a cutting edge of the cutter element. The PCD volume comprises a plurality of strata directly joined to each other at inter-strata boundaries, in which each of a first plurality of the strata comprises PCD material having a first diamond content; each of a second plurality of the strata comprises PCD material having a second diamond content; the second diamond content being greater than the first diamond content; and the strata of the first and second pluralities disposed in an alternating arrangement with respect to each other.

Abstract: A cutter element for an earth-boring tool, comprising a polycrystalline diamond (PCD) volume joined at an interface boundary to a cemented carbide substrate. The PCD volume includes a rake face opposite the interface boundary, an edge of the rake face being suitable as a cutting edge of the cutter element. The PCD volume comprises a plurality of strata directly joined to each other at inter-strata boundaries, in which each of a first plurality of the strata comprises PCD material having a first diamond content; each of a second plurality of the strata comprises PCD material having a second diamond content; the second diamond content being greater than the first diamond content; and the strata of the first and second pluralities disposed in an alternating arrangement with respect to each other.

Abstract: A superhard insert for a rotary earth borer tool comprises a cutter end having a peripheral cutter edge, at least part of the peripheral cutter edge being defined by a plurality of edges of a plurality of alternate hard and superhard regions. The edges of the superhard regions are arranged spaced apart from each other and are separated by edges of hard regions. The hardness of each hard region is at most 50% of the hardness of each superhard region.

Abstract: A cutter insert assembly for a drill bit for boring into the earth, comprising a super-hard structure clampable to a support body by means of a clamp mechanism; the clamp mechanism comprising opposed or opposable compression members connected or connectable by a tension member capable of sustaining a clamping force between the compression members when the cutter insert assembly is in a clamped condition, in which condition the compression members exert opposing compressive forces on the super-hard structure and the support body, operable to clamp the super-hard structure to the support body, and in which condition the cutter insert assembly is self-supporting and capable of being mounted onto a drill bit body.