Fiber discs are used for stock removal, grinding, blending, and weld dressing. They are constructed with a fiber backing and are resistant to tearing and loading. A backing pad with retainer nut, adhesive or clamp is needed for mounting to the sander or grinder.
Coated abrasives can be used for most applications, from grinding to polishing. They consist of a thin layer of abrasive adhered to fiber, paper, cloth or rubber. Coated discs are normally used on angle grinders.
Choosing the correct abrasive material for your surface can shorten grinding time, reduce cost, and prevent premature wear. Aluminum oxide, for example, is a great all-around abrasive material, while diamond is used on specific materials like ceramic.
Aluminum oxide is the most commonly used abrasive. Best-suited for general purpose deburring and blending, it is tough, economical and fracture-resistant. Commonly used on ferrous alloys, high-tensile materials, and wood.
Cooler-cutting and more durable than natural aluminum-based products, ceramic provides a sharp, high-purity grain. Commonly used for precision grinding of steels, hard alloys and exotic materials.
More durable than aluminum oxide, zirconia-alumina is best for medium- to heavy-material removal. The material grains constantly fracture to produce new sharp edges. Commonly used on carbon steels, aerospace alloys, nickel alloys, aluminum, cast iron, forgings and some stainless steels.
Grit
Use larger grits/coarser grades for removing more material over a larger contact area. Use smaller grits/finer grades where the final finish is important. The chart below applies to only ANSI grit sizes.
Fiber discs are used for stock removal, grinding, blending, and weld dressing. They are constructed with a fiber backing and are resistant to tearing and loading. A backing pad with retainer nut, adhesive or clamp is needed for mounting to the sander or grinder.
Abrasives 
