MACHINING OF ABRASIVE MATERIALS WITH DIAMOND-COATED TUNGSTEN CARBIDE INSERTS

Diamond coatings deposited by chemical vapor deposition onto cobalt-consolidated tungsten carbide inserts can provide a new class of cutting tool for the machining of very abrasive, non-ferrous materials, particularly Al-Si compounds. However, poor adhesion of the diamond film to the tungsten carbide substrate has prevented the commercialization of these tools. Using a proprietary process, diamond films have been deposited on C-2 grade tungsten carbide inserts (6% Co binder), from a number of different insert manufacturers, and tested under conditions as severe as dry turning of 390 Al at a cutting speed of 1400 m min-1. Under these aggressive machining conditions, the diamond-coated tools exhibit a flank wear rate equivalent to that of polycrystalline diamond and fail by a gradual wear out mechanism rather than film spalling.