Abstract: This disclosure relates to a high pressure grinding roller stud comprising two materials of different hardness, and a high pressure grinding roller incorporating at least one such stud.

Abstract: An attack tool assembly (10) comprising an attack tool having a shank (23) extending therefrom, the shank (23) having a longitudinal axis; and a holder having a holder body (31) and a bore for receiving the shank (23) of the attack tool (10); the holder being adapted to receive the shank (23) in a configuration in which it prevents the shank (23) from rotating relative to the bore when the holder is in an engaged condition, and in which it allows the shank (23) to be rotatable relative to the bore when the holder is in a disengaged condition, so as to enable the shank (23) to be selectively securable to the holder in a required orientation about the longitudinal axis. The attack tool assembly (10) is particularly but not exclusively for use in the degradation of rock or asphalt bodies for formations, such as in soft rock mining and asphalt milling.

Abstract: This invention relates to a percussion drill bit head for a percussion drilling apparatus, the drill bit head comprising a working surface and a plurality of super-hard buttons protruding from the working surface, the working surface having a hard area that is free of buttons and has Rockwell C hardness of at least 60 HRc. The invention further relates to a method of manufacturing a percussion drill bit head comprising a working surface and a plurality of buttons and a percussion drill bit assembly comprising a drill bit head according to the invention.