TOOL TALK Bonded Abrasives: Grains, Grits, and Grades Bonded abrasives are comprised of a mix of abrasive grains, fiberglass, and bonding materials made into wheels and used on handheld machines such as angle grinders, gas saws, and straight grinders. As the wheel spins against the surface of a work piece, the grains fracture and dull. As the grains dull and deplete, the wheel gradually breaks down, exposing fresh, sharp grains, and the wheel continues to shrink in diameter. Uses Used primarily for cutting applications and aggressive stock removal. Bonded abrasive products include cut-off and grinding wheels and are available in several shapes and profiles to fit an extensive variety of metalworking applications. Grains The cutting power of an abrasive grain depends on shape, hardness, and toughness. All three factors control the penetration of cut and the life of the grain. Sharper grains produce a cleaner cut and tend to stay cooler during use. Blocky grains give a rougher cut and create more friction. Different applications require different types of abrasive grain. Aluminum Oxide is the most common abrasive grain in use today. AO is tough and durable, with no clearly defined crystal structure. As the grain wears, it produces rounded edges reducing cutting power but leaving a consistent surface finish. BEST ON: Steel. Zirconia Alumina is an alloy of aluminum oxide and zirconia with a crystalline structure. They maintain their sharpness for a longer period of time and are better suited to more aggressive grinding applications. BEST ON: Steel. Ceramic Grains are formed via a chemical process. The grain consists of millions of smaller crystals, which fracture off during use and continuously form a new cutting surface. This self-sharpening process requires pressure and tool power to ensure that the grains do not glaze. BEST ON: Steel, stainless, and hard to grind metals. Soft Grade • Faster cut rate • Smoother • Shorter wheel life Hard Grade • Longer wheel life • More susceptible to loading/glazing •Prone to chatter on light duty grinding applications SIZE 2" 3" 4" 4.5" 5" 6" 7" 9" 12" 14" DIE GRINDERS GRINDERS 1/4" & 3/8" Arbor 5/8" Arbor ANGLE GRINDERS 7/8" Arbor or 5/8"-11 Nut SAWS 1" Arbor Aluminum Zirconia Ceramic Oxide (AO) Alumina (ZA) Looking for Metalworking Tools? Contact Fastenal at 844.365.8665 or cuttingtoolsupport@fastenal.com Go to fastenal.com/metalworking for previous Tool Talks INCD0112099 JP 9.22
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