Of agglomerated synthetic or natural diamond

68.04 Millstones, grindstones, 'ndig wheels and the like, without frameworks, for grinding, sharpening, po shing, trueing or cutting, hand sharpening or polishing stone!, and parts thereof, of natural stone, of a lomerated natural or artificial abras~ves,or of ceramics, with or without parts of ot er materials (+). k 6804.10 - Millstones and grindstones for milling, grinding or pulping - Other millstones, grindstones, grindingwheels and the like : 6804.2 1 - - Of agglomerated synthetic or natural diamond 6804.22 - - Of other agglomerated abrasives or of ceramics 6804.23 - - Of natural stone 6804.30 - Hand sharpening or polishing stones This heading covers, in particular : (1) Millstones and grindstones, often of considerable size, for crushing, rinding, pulping, I! etc., (e.g., for m~llinggrain (upper or lower stones); pulping wood, as estos, etc.; papermakers' or paint mixers' grindstones). (2) Grindstones for shar enin cutlery, tools, etc., and designed for mounting on hand, pedal or power operate mac ines. i' b L r dstones and millstones described in the two categories above are usually flat, The cylin cal or in the shape of truncated cones. (3) Grinding wheels, heads, discs, points, etc., as used on machine-tools, electro-mechanical or pneumatic hand tools, for the trimming,polishing, sharpenin truein or sometimes for the cutting of metals, stone, glass, plastics, ceramics, rubber, leaPi;er, rno er of pearl, ivory, etc. f Exc t for some cutting discs, which may be of considerable diameter, these oods are usua y much smaller than those described above, and they may be of any sha e, $e.g, flat, conical, spherical, dished, ring-shaped, recessed or stepped); they may also e planed or profiled at the edges. ? 'i The heading covers such tools not only when the are predominantly of abrasive materials, but also when they consist of only a very smal abrasive head on a metal shank, or of a centre or core of rigid material (metal, wood, plastics, cork, etc.) on to which compact layers of a lomerated abrasive have been ermanently bonded e.g., cutting discs of metal, etc., itted with rims or with a series o peripheral inserts of a raslve material). The heading also covers abrasive elements for hones, whether or not they are mounted in the carriers required for their fixation in the body of the hone. ? !P ? b It should, however, be noted that certain abrasive tools are excluded and fall in Chapter 82. The latter Cha ter, however, covers only those tools with cutting teeth, flutes, grooves, etc., which retain t eir identity and h c t i o n even after application of the abrasive material i.e., tools which, unlike those of this headin , could be put to use even if the abrasive ad not been a plied). Saws with cutting tee covered with abrasive therefore remain in heading 82.04. Similarly crown drills as used for cutting discs from sheets of lass, quartz, etc., are classified in this heading if the worhng edge is smooth a art from the abrasive coating, but in heading 82.07 if toothed (whether or not coated with a rasive). I R th \ (4) Polishing stones, whetstones, oilstones, hones and the like, with or without handles, used directly in the hand for sharpening, whetting, scouring or polishing metals or other materials. r The may be of various shapes e ., rectangular, trapezoidal, sectors or segments of a circ e, in the form of a kmfe b a e, oblong with ta ered ends), and may be square, triangular, round, half round, etc., in cross-section. d e may also consist of prismatic plates, generally of agglomerated boron carbide, use in the hand, for whetting or sharpening grindstones of artificial abrasives, and, as a secondary use, for sharpening metal tools. \f These stones are used, in particular, for sharpening tools and cutting instnunents (e.g., cutlery, blades for harvesting machines, sickles, scythes, mowers, etc.), or for polishing metal, etc. Tools with a fine cutting edge (e. ., razors or surgical instruments) are sharpened with oilstones or hones made of specia ly fine- ain stone or slate; these stones are usually moistened with water or oil before use. 8rtain stones (e.g., pumice) are also used for toilet, manicure and pedicure purposes, and also for the cleaning up, polishing, etc., of metals, etc. stone, agglomerated ,of agglomerated glass, corundum, or refractory earths, or Grindin stones, grinding wheels, etc., must be or not, (g,.g,sandstone, granite, lava, flint, rnol?sse, natural or artificial abrasives (e.g., emery, urmce, silicon carbide, garnet, diamond, boron car ide) or o of porcelain). \ Ag lomerated grinding wheels, etc., are made by mixin ground abrasive or stone with binders suc as cerarmc materials (for example, powdered c ay or kaolin, sometimes with added feldspar), sodium silicate, cement (especially magnesian cement) or less ri materials (such as rubber, shellac or plastics). Texhle fibres such as cotton, ny on or flax are sometimes incorporated in the mixtures. The mixtures are moulded to shape, dned, and then heated (if necessary to the stage of vitrification in the case of ceramic binders) or cured (in the case of the rubber, plastics, etc., binders). The articles are then trimmed to size and shape. fi Pd In making certain polishing stones (oil stones), washed abrasive powders are used. Grinding stones of this heading, and especially those for granary use or for pulping, sometimes have a nbbed surface. They may be in one piece or made up of assembled segments, be fitted with sockets, internal or external hoops, balancin weights or cavities; they may also be fitted with axles or spindles, but they must be without rameworks. Grinding stones wtth frameworks are classified m heading 82.05 if hand or pedal operated or in Chapter 84 or 85 if power operated. ? In addition to the corn lete millstones, grindstones, etc., described above, the heading also covers identifiable b l a d s ; segments and finished parts of such goods, if essentially of stone, agglomerated abrasives or ceramics are also included. The heading does not include : (a) Perhmed pumice stone put up in blocks, tablets or similar prepared forms of heading 33.04. (b) Natural or artificial abrasive owder or gain coated on to textile material, paper, paperboard or other materials (heading 68.05), w h e r or not the textile material, paper, etc., is subsequently lued on to support! such as discs or strips of wood (buff-sticks for use in the clock and watct industry, mechanical engineering, etc.). (c) Dental burrs (heading 90.18).