The ornamental rock processing is carried out mainly using diamond tools. These are currently being produced by powder metallurgy (PM) techniques from diamond and blend powders. In view of the diversity of materials processing routes available, natural materials, and the different processes used in rock processing, diamond tools best suited to each material require formulation of specific compositions capable to achieve suitable performances at a cost as low as possible.

Not surprisingly, the main market players in diamond tools processing are investing, through R&D in this field, in the development of novel powders, either elementary or pre-alloyed, the latter with increasing potential but also higher cost. In this context, manufacturers of diamond tools are faced with new challenges, namely how to select the most suitable powders available in the market without significant increase in production costs? This paper highlights the importance of powder's characterization as an effective tool for selecting raw materials adequate for manufacturing of diamond impregnated tools (DITs) at a reasonable cost. Since such tools are made of mixtures of metallic powders and diamonds, special attention will be paid to the main powder characteristics which need to be taken into account in the selection procedure.

History at a glance

Back in 1862 the Swiss engineer J.R. Leschot devised the idea of making diamond drill bits which soon found practical appliance. The first diamond circular saw blades for cutting stone were developed by Felix Fromholt in France in 1885. Progress in the tool manufacturing routes, by making use of PM techniques, resulted in developing diamond grit impregnated saw blades, which were put into operation around 1940. Further developments in diamond tool manufacturing technology are attributed to the invention of synthetic diamonds at ASEA (Allmänna Svenska Elektriska Aktiebolaget), one of Sweden's major electrical manufacturing companies, in 1953, but this work was not reported until the 1980s. Two years later, General Electric (GE) announced on February 15, 1955, its capability to manufacture synthetic diamonds on an industrial scale. Nowadays, synthetic grits account for around 97% of all industrial diamonds consumed. The market of diamond tools continues to grow steadily. By far the largest group of diamond tools comprises the well-known ‘metal-bonded’ DITs including circular saw blades, wire saws and core drills commonly used for cutting natural stone and civil engineering applications.

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