Grinding Wheels - 5: Grain and Bond
|WARNING: Machine tools present a safety hazard. Improper operation can result in severe injury. These topics are for non-laboratory study only and are not to be used in conjunction with the operation of any tool or machine described herein. Never use a machine tool without the supervision of a qualified instructor.|
|There are six different ranges of grain, from very coarse to very fine. Grain sizes are selected according to the type of finish desired, the material being ground, and the amount of material being removed.
If the grinder is performing a roughing operation, a course grain would be selected, providing maximum metal removal. Likewise, finer grains are used for minimum material removal and high surface finish requirements.
The function of the bonding agent is to unite all of the abrasive grains into a wheel. There are six types of bonding agents: vitrified, Profilometer, rubber, shellac, silicate and metal. The vitrified type is used on most abrasives. In the resinoid bond, synthetic resins are used to unite the grains of the abrasive. A resinoid bonded wheel produces a higher surface finish, and should be run at a higher surface feet per minute than the vitrified bond