Abstract: A composite diamond abrasive compact comprises a diamond compact bonded to a cemented carbide support along a compact/carbide interface and is characterised by the carbide support comprising at least two zones, a first zone containing a binder metal content of a predetermined amount, and a second zone extending from the interface to the first zone and having a binder metal content which is substantially lower than that of the first zone. The second zone has a depth or thickness of no more than 0,75 mm. The binder metal content of the second zone increases from the interface to the first zone in a continuous, non-interrupted manner.

Abstract: A cutting insert for a rotary cutting tool comprises a body of tungsten carbide, with layers of polycrystalline diamond on opposite sides of the body. The diamond layers overlap across the centre-line of the insert. The cutting insert is shaped for retention at the end of the rotary cutting tool so that the first and second sides of the cutting insert are substantially parallel to the axis of the cutting tool, and the diamond layers are offset from one another across the width of the body so that they define the lips or major cutting edges of the cutting tool.

Abstract: A cutting insert for a rotary cutting tool comprises a body of tungsten carbide, with layers of polycrystalline diamond on opposite sides of the body. The diamond layers overlap across the centre-line of the insert. The cutting insert is shaped for retention at the end of the rotary cutting tool so that the first and second sides of the cutting insert are substantially parallel to the axis of the cutting tool, and the diamond layers are offset from one another across the width of the body so that they define the lips or major cutting edges of the cutting tool.

Abstract: A method of producing an abrasive body which consists of an abrasive compact sandwiched between layers of cemented carbide. The method includes the steps of providing an unbonded structure comprising a layer of ultra-hard abrasive particles sandwiched between two carbide layers. Each carbide layer is a layer of cemented carbide or a layer containing the components necessary to produce cemented carbide. The two carbide layers and the sandwiched layer each contain a binder metal selected from cobalt, nickel, iron and the like. The concentration of binder metal in the sandwiched layer is less than the concentration of the binder metal in one of the carbide layers, and is higher than the concentration in the binder metal in the other carbide layer. The unbonded structure is subjected to conditions of elevated temperature suitable to produce the abrasive body.