Abstract: This disclosure relates to a friction stir welding (FSW) tool assembly comprising a retention mechanism to mechanically engage both a tool insert and a tool holder, thereby preventing relative separation. The retention mechanism comprises an annular locking collar mounted about the tool insert and/or the tool holder that couples with the tool insert and/or the tool holder, in mating engagement.

Abstract: This disclosure relates to a friction stir welding (FSW) tool assembly comprising a bonding layer to bond the tool insert and the tool holder together, wherein the bonding layer is a layer of braze with a melting temperature of at least 900° C.

Abstract: A cutting element (30) includes a substrate (40) having a peripheral side edge, the peripheral side edge having an associated radius of curvature; and a body of superhard polycrystalline material bonded to the substrate along an interface, the body of superhard polycrystalline material (39) having a peripheral side edge and a longitudinal axis. The body of superhard polycrystalline material (39) has a working surface (54); and a plurality of spaced apart cutting edges extending to the working surface (54) through respective chamfer portions (62), the cutting edges (61, 76) being spaced around the working surface by a further region. The cutting edges (61, 76) have an associated radius of curvature, the radius of curvature of one or more of the cutting edges being less than the radius of curvature of the substrate. A method of making such a cutting element is also disclosed.