Aluminum Oxide
is made by refining bauxite ores. The degree of refinement is reflected in the color and toughness of the grain. Darmann uses two types of high purity aluminum oxide grains. Sintered white aluminum oxide (WA) is the purest and most friable form of aluminum oxide. Fused white aluminum oxide (FA) is also a highly pure grain, with a more angular shape. It is typically used for “roughing” operations.
Silicone Carbide
is made by combining pure white quartz, petroleum coke, sawdust and salt in an electric furnace. Hardness and purity are determined by the color of the crystals. Green silicon carbide (GC) is the purest form, while black silicon carbide (C) is less pure. Silicone carbide is a harder material than aluminum oxide, and has excellent finishing characteristics.
Cubic Boron Nitride
(CBN) is a boron nitride allotrope with a crystalline structure similar to that of diamond. CBN has a high thermal stability, and is not soluble in ferrous materials at higher temperatures, making it an ideal crystal for finishing steels. CBN crystals are available in a range of particle shapes, toughness, mesh sizes and coatings which allows for wide latitude in customizing superabrasive products. Nickel or titanium coating can lead to better bond retention and increased heat dissipation especially for resin bonds.
Diamond
is significantly harder than conventional abrasive particles such as aluminum oxide and silicon carbide. Since carbon is soluble in iron at high temperatures, diamond is most often used when machining non-ferrous metals or ceramics. Synthetic diamonds are grown in a controlled environment with controlled defects and hardness properties. Darmann manufactures stones and wheels with high-purity synthetic diamond, which helps to maintain consistent performance.