There are three cutting grains commonly used in bonded abrasive cutting wheels:
aluminum oxide, zirconia alumina and ceramic alumina.
Aluminum oxide wheels provide an aggressive cut out of the box,
but immediately begin dulling from the first cut.
Ceramic alumina grains self-sharpen
and are the most resistant to heat, providing a consistently high cut rate and longer life.
Zirconia alumina grains are harder and sharper than aluminum oxide grains
and provide an excellent value.
Keep in mind that product cost also typically increases along with durability and cut rate.
Aluminum oxide wheels utilize softer bonds that are less resistant to heat, resulting in a cut that is fast, smooth and easy-to-control. However, they are by far the least durable of the three grains. Aluminum oxide wheels are the most economical and have a high initial cut rate, but the tradeoff is shorter product life. As a result, aluminum oxide wheels are ideal for cutting milder alloys such as carbon steels. White aluminum oxide wheels provide increased durability and cut rate, while maintaining a lower cost of use.
Zirconia alumina is a harder, tougher grain that is more resistant to heat than aluminum oxide. Zirconia alumina grains also maintain sharpness longer than an aluminum oxide grain. As a result, zirconia alumina wheels cut faster throughout the cutting process. Their increased toughness makes them more resistant to heat and allows for harder bonds, resulting in longer life. Zirconia alumina cutting wheels provide an excellent overall value as they do not need to be replaced as often, reducing product changeover while also minimizing costly operator downtime.
Ceramic alumina grains are designed to self-sharpen and are also more durable, making them the most expensive choice. Ceramic grains are manufactured with thousands of fracture points designed to fracture and chip during use so they self-sharpen — rather than dull — throughout the cutting process. As a result, ceramic alumina wheels maintain their sharpness and cut rate for roughly 75 percent of their lifespan before an operator feels a decrease in cutting performance.