Norton NorZon Plus Type 27 depressed center wheels are suitable for faster cutting and longer life than an equivalent aluminum oxide wheel. Run the grinder at the highest possible speed marked on the wheel. Reinforced cutoff wheels are designed to resist breakage caused by severe cross-bending and are required on any operation where the work is not securely clamped. Resin bonds are organic bonds that soften under the heat of grinding, releasing dulled abrasive grains. Because of its forgiving nature, only an organic type bond is used in cutoff wheels. The resin-bonded wheel is more resilient than a vitrified wheel. The manufacturing term for a resin bond wheel is "cured," meaning the wheel has been heated to less than 500 degrees F. Depressed center wheels are flat faced with inset centers and are used for cutting off and portable grinding. The depressed center prevents the tool mandrel from gouging the workpiece. These wheels are typically used on flat workpieces at a slight angle with the workpiece. Depressed center wheels are frequently used with right-angle grinders. Using a harder grade wheel increases wheel life but also increases burn and requires more power, and decreases cut rate. Burn is the effect on a workpiece from thermal stress as abrasive cuts or rubs material away. The damage ranges from discoloration to cracking of the workpiece. Zirconia alumina is a self-sharpening abrasive that allows for a faster cut rate and longer life than aluminum oxide, due to its ability to fracture and refracture, creating new cutting edges. Zirconia alumina is often used for high stock removal on metals and wood. Aluminum oxide is a widely used and versatile abrasive material. It is a tough, fracture- and wear-resistant grit that works well with a broad range of materials, from metals to wood. Aluminum oxide is more durable than silicon carbide and often used for material removal and finishing. Abrasives are used for a variety of applications from shaping a part to fine finishing, depending on the grit size. Low grit numbers like 40 are coarse and are used for removing excess material and shaping a part. High grit numbers like 400 are fine and help to create a smooth surface finish. Norton Abrasives manufactures a wide variety of sanding, grinding, and polishing abrasives, and has been located in the United States since 1885. In 1990, Saint-Gobain purchased Norton, keeping its manufacturing facilities and offices in the same location. Norton/Saint-Gobain has been recognized as a Global 100 Sustainable Company, as well as earning ISO 9000 and 14001 certification for quality and environmental management standards.