Grinding Wheel - Characteristics

Characteristics

There are five characteristics of a cutting wheel: material, grain size, wheel grade, grain spacing, and bond type. They will be indicated by codes on the wheel's label.

Material, the actual abrasive, is selected according to the hardness of the material being cut.

• Aluminium Oxide (A)
• Silicon Carbide (S)
• Ceramic (C)
• Diamond (D, MD, SD)
• Cubic Boron Nitride (B)

Grain size, from 8 (coarsest) 1200 (finest), determines the physical size of the abrasive grains in the wheel. A larger grain will cut freely, allowing fast cutting but poor surface finish. Ultra-fine grain sizes are for precision finish work.

Wheel grade, from A (soft) to Z (hard), determines how tightly the bond holds the abrasive. Grade affects almost all considerations of grinding, such as wheel speed, coolant flow, maximum and minimum feed rates, and grinding depth.

Grain spacing, or structure, from 1 (densest) to 16 (least dense). Density is the ratio of bond and abrasive to air space. A less-dense wheel will cut freely, and has a large effect on surface finish. It is also able to take a deeper or wider cut with less coolant, as the chip clearance on the wheel is greater.

Wheel bond, how the wheel holds the abrasives, affects finish, coolant, and minimum/maximum wheel speed.

• Vitrified (V)
• Resinoid (B)
• Silicate (S)
• Shellac (E)
• Rubber (R)
• Metal (M)
• Oxychloride (O)