Binder for diamond tools: M.Bonneau. (Eurotungstene, Grenoble, France.)

Abstract

About 250 tons of industrial diamonds are consumed world wide each year as superabrasives for cutting, drilling, sawing, grinding or polishing materials. Sawing constructional materials (e.g. rock and concrete) accounts for about one-third of the diamond used but with over half of the total value. However, <10% of the diamond is actually worn out in sawing the work material, the bulk is wasted primarily because the distribution of grits is poor and the bonding of diamond is weak.Diamond grits in conventional tools are held in matrix either by electroplated nickel or sintered metal. As a result, these grits are distributed randomly and they are buried mechanically. The segregation of diamond grits often results in densely and sparsely spaced regions. Thus, some grits are wasted due to redundancy; and others, shattered because of overload. Moreover, as the mechanical retention force is weak, all grits are easily knocked off by the strong impact force generated during cutting.Diamond grits can now be set in a grid pattern and they are brazed firmly in the tool. The controlled spacing of diamond allows optimal performance of each grit with minimal waste. The chemical bonding further prevents premature loss of the grit. Moreover, brazed diamond can protrude higher for aggressive cutting. The new technology has been applied to make diamond wire saws with half the amount of diamond used as compared with conventional diamond wires. The brazed diamond grid allows a two-fold increase of cutting speed over conventional diamond saws without compromising the life. If this technology is applied to other types of diamond saws, the result would be a dramatically improvement of productivity accompanied by a sizable reduction of cost.