What is a Grinding Wheel?
A grinding wheel is composed of an abrasive compound. The expendable wheel is used for abrasive cutting or grinding. Wheels are made of coarse particles bonded to form a solid wheel. Steel or aluminum discs with particles bonded to the surface may also be used. Various profiles and cross sections are available, depending on use. Variables include material, grain size, grade, grain spacing, and bond type.
The material chosen will depend on what is being cut. Aluminum Oxide will be labeled A, Silicon Carbide (C), Diamond (D, MD, SD), and Cubic Boron Nitride (B). Diamond wheels are used for grinding extremely hard surfaces like carbide cutting tips, gemstones, and concrete.
Grain size ranges from a fine 600 to a coarse eight. The size of the abrasive grains will allow everything from fast cutting to precision finish work. Wheel grades go from a soft A to a hard Z. the grade tells you how tightly the bond holds the abrasive. This will affect wheel speed, coolant flow, feed rates, and grinding depth.
Grain spacing will be rated from a dense one to a less dense 16. The ratio of bond and abrasive to air space will affect surface finish. Less dense means free, deep cutting. Less coolant is needed when chip clearance is greater. Wheel bond also affects coolant. How the wheel holds the abrasives additionally affects finish and wheel speed. You’ll choose from Vitrified (V), Rubber (R), Silicate (S), Shellac (E), and Oxychloride (O).
Types of Grinding Wheels
Straight wheels are the most common. Found on bench or pedestal grinders, they are used on the periphery to create a slightly concave surface. These wheels are used for cylindrical, centerless, and surface grinding. You’ll find a wide variety in sizes to suit variances in grinding machine size, power, and work class.
Cylinder wheels have a long, wide surface. They are hollow, without a center mounting support. You’ll find cylinder wheels up to 12 inches wide. Cylinders produce flat surfaces. The end face of the wheel does the work. The wheel ring or cylinder is only used in vertical or horizontal spindle grinders.
Tapered wheels taper toward the center of the wheel. Stronger than straight wheels, they can accept higher lateral loads. This type is used for grinding thread or gear teeth.
Straight cups afford additional grinding surface. A dish cup is a very shallow style wheel used in cutter and jig grinding. The thinness allows for grinding in tight places. Saucer wheels are used in saw filers to grind milling cutters and twist drills.