Bonded Abrasives Information

Bonded abrasives contain abrasive grains held together in a matrix of glass, resin, rubber, or other binders. They are used to remove surface materials such as metal, ceramics, glass, plastics, and paint. Bonded abrasives are used in both grinding wheels and abrasive stones or sticks. Grinding wheels are used in a variety of applications and industries, while abrasive stones or sticks are used for sharpening edges and honing internal or external surfaces. 

Types

Grinding wheels with bonded abrasives can have several shapes. Some wheels are flat or have a raised center with a cone or cylinder mounted on a pin or mandrel. Other wheels have a depressed center, a cup or bowl shape, a tapered body, or a donut or ring shape.

Depressed center wheels are used to saw metal bars or remove masonry products.

Cup-shaped wheels can be either straight or flared.

Recessed, or relieved, wheels may be recessed on only one side or on both sides.

Tapered body wheels have a thicker cross-section at the bore, which becomes thinner or tapers toward the outer diameter. To account for the differences, ANSI standards are also used.

Specifications

Grit size measures the abrasive grains in a matrix or bonded to a surface. Typically, grit sizes are based on ANSI (U.S.), FEPA (European), JIS (Japanese), or Micron graded standards. Coarse grains, or grits, remove large amounts of material. Medium grains remove less material, but provide a better finish than coarse grits. Fine grits are suitable for light cutting and finishing, while very fine grits are used to improve finish. The abrasive grains in bonded abrasives use several different bond types. Some use an electroplated or brazed metal bond between the abrasive grains, or between the grains of a metal substrate. Others use a shellac, resin, rubber, or glass bond system between the abrasive grains. Low-strength bonds such as silicate minimize heat generation, but lack the life and durability of vitrified or resin bonds. Reinforced bonds use a fiberglass mesh or other fibers or materials to improve the structural integrity of bonded abrasives. Bonded abrasives use several different types of abrasive grains.

Aluminum oxide, the most common industrial mineral in use today, is used either individually or with other materials to form ceramic grains. Aluminum oxide is also combined with emery and crocus to produce abrasives suitable for finishing applications.

Other types of abrasive grains include garnet, tungsten carbine, silicon carbide, and alumina-zirconia. Super-abrasive diamond pastes are useful in ferrous polishing or lapping applications where heat and reactivity are not a factor. Cubic boron nitride (CBN), a superabrasive grain with hardness second to diamond and a cubic crystal structure, provides superior grinding performance on carbon and alloy steel. There are several ways to mount bonded abrasives. For example, hook and loop mounting attaches the abrasive using a hook and loop fabric whereas bore / center mounting uses a central hole for mandrel, arbor, spindle, or shaft mounting. Other types of bonded abrasive mounting include quick change and PSA / adhesive.

Standards

AGA 3 -  Abrasive grain in bonded abrasive products

BS ISO 525 -  Bonded abrasive products - general requirements

ANSI B74.13 -  Marking for identifying grinding wheels and other bonded abrasives