Graphite containing metal bonded diamond abrasive wheels

Claim 1

A CUP-TYPE DRY GRINDING WHEEL HAVING AN ABRASIVE SECTION CONSISTING OF RESIN BOND TYPE DIAMOND ABRASIVE GRAINS BONDED IN A METAL MATRIX HAVING A MELTING POINT ABOUT 300*C. SAID METAL MATRIX INCLUDING A FILLER SELECTED FROM THE GROUP CONSISTING OF PARTICULATE POLYTETRAFLUOROETHYLENE, GRAPHITE, HEXAGONAL BORON NITRIDE, MOLYBDENUM DISULFIDE, AND MIXTURES THEREOF IN THE AMOUNT OF FROM 15 TO 50% BY VOLUME OF THE BOND, SAID FILLER HAVING A PARTICLE SIZE OF BETWEEN 1 MICRON AND 200 MICRONS, THE SMALLER SIZE FILLER BEING PRESENT AT THE LOWER CONCENTRATIONS OF FILLER, THE LARGER SIZE FILLER BEING PRESENT AT THE HIGHER FILLER CONCENTRATIONS, SAID DIAMOND ABRASIVE GRIT BEING DEFINED BY ONE OF THE FOLLOWING LISTS (A), AND (B) OF CHARACTERISTICS: (A) SYNTHETIC MULTICRYSTALLINE DIAMOND HAVING AN IRREGULAR SURFACE AND A FRIABILITY INDEX F, FOR GRIT SIZES OF 130 AND COARSER EQUAL TO OR LESS THAN 0.0052S2, AND EQUAL TO OR LESS THAN 1.07S0.9, FOR GRIT SIZES FINER THAN 130, WHEREIN S IS THE ARITHMETIC AVERAGE OF THE NUMBER DESIGNATIONS OF THE U.S. STANDARD SIEVE SERIES SCREENS USED TO OBTAIN A SIZED SAMPLE OF THE DIAMOND, AND (B) NATURAL MONOCRYSTALLINE DIAMOND WITH A FRIABILITY INDEX OF LESS THAN 11.3S**0.43 AND IS SELECTED FROM A POPULATION HAVING A BULK DENSITY OF 1.7 OR LESS IN THE 140/170 GRIT SIZE AND 1.6 OR LESS IN THE 200/230 GRIT SIZE AS MEASURED BY THE AMERICAN NATIONAL STANDARDS INSTITUTE METHOD.