Patent ID: 8523966

Claim:
Method for applying a coating of powdered diamond to the surfaces of cutters, especially used in dentistry, said cutters consisting of oblong metal bodies of cylindrical symmetry, a fraction of their surfaces being grooved by one or more slots ( 5 , 6 ) that continue downward to the tip ( 4 ), said method including the stages of: a) surface passivation by immersing the cutters in a concentrated aqueous solution of nitric acid for a certain length of time; b) masking the surfaces which are not to be diamond coated, using an electrically insulating paint ( 20 ) resistant to acids; c) activation of the unmasked surface by electrolysis of reversed polarity in a Wood bath for the removal of metal; d) electrolytic nickel-plating, in a Wood bath, of the surface so activated; e) application of a powdered-diamond coating to the surface, nickel-plated in stage d), by application of a second electrolytic nickel-plating process in a Watts bath ( 15 ) where powdered diamond ( 14 ) is in contact with the cutters; f) stabilization of the powdered diamond by a third electrolytic nickel-plating process in a Watts bath; g) removal of the residual insulating paint ( 20 ) by immersing the diamond-coated cutters in a non-halogenous solvent, characterized in that said masking at stage b) includes: h) painting of a length comprising the surface ( 7 ) external to the slots ( 5 , 6 ), the surface inside the slots ( 5 , 6 ) and the surface of the tip ( 4 ); i) grinding of each cutter using a grinding wheel with rotating disk ( 21 ) having an abrasive edge ( 22 ) shaped crosswise to match the continuous profile of the painted surface external to the slots ( 5 , 6 ).