Grinding wheels come in many different sizes, shapes, and abrasives (Figure 5-7).
Figure 5-7. Standard types of grinding wheels.
Straight. Straight wheels, numbers 1, 5, and 7, are commonly applied to internal, cylindrical, horizontal spindle, surface, tool, and offhand grinding and snagging. The recesses in type numbers.5 and 7 accommodate mounting flanges. Type number 1 wheels from 0.006-inch to l/8-inch thick are used for cutting off stock and slotting.
Cylinder. Cylinder wheels, type number 2, may be arranged for grinding on either the periphery or side of the wheel.
Tapered. Tapered wheels, type number 4, take tapered safety flanges to keep pieces from flying if the wheel is broken while snagging.
Straight Cup. The straight cup wheel, type number 6, is used primarily for surface grinding, but can also be used for offhand grinding of flat surfaces. Plain or beveled faces are available.
Flaring Cup. The flaring cup wheel, type number 11, is commonly used for tool grinding. With a resinoid bond, it is useful for snagging. Its face may be plain or beveled.
Dish. The chief use of the dish wheel, type number 12, is in tool work. Its thin edge can be inserted into narrow places, and it is convenient for grinding the faces of form-relieved milling cutters and broaches.
Saucer. The saucer wheel, type number 13, is also known as a saw gummer because it is used for sharpening saws.
The abrasive grains are the cutting took of a grinding wheel. They actually cut small pieces or chips off the work as the wheel rotates. The shape of each grain is irregular with several sharp cutting edges. When these edges grow dull, the forces acting on the wheel tend to fracture the abrasive grains and produce new cutting edges.