A rotary tool for cutting, drilling, grinding, or polishing metallic or non-metallic materials is made of a compact material, which consists of an inorganic fiber reinforced plastic containing 50 to 81 volume % of inorganic long fibers selected from the following group: alumina fibers, boron fibers,...http://www.google.de/patents/US5233794?utm_source=gb-gplus-sharePatent US5233794 - Rotary tool made of inorganic fiber-reinforced plastic
