Norton/St. Gobain, in addition to being a top manufacturer of grinding wheels, is a great source of technical information. If you are not sure when your grinding wheel is coming to the end of its use, here are some guidelines to follow for the most common types of grinding wheels. This information and more can be found in the Resources section on St. Gobain’s website.
Straight Wheels (Type 1)
According to the ANSI B7.1-2000 standard, “The usable portion of an abrasive wheel shall be considered to be that portion which extends beyond the mounting flanges. A wheel shall not be worn down to a size which would allow the mounting flange assembly to contact the work piece or work piece holding fixture.” This rule assumes the proper flanges are being used and the correct machine guarding is in place.
WARNING: You should never grind with the fine center of a wheel and if you are using a super abrasive (diamond) wheel do not grind with the wheel’s core.
Cylinder Wheels and Segments (Type 2)
The wheel will no longer be usable when the down feed mechanism of the machine keeps the wheel from contacting the work piece.
WARNING: It is important to use the proper mounting procedures with this type of product. Do not loosen the mount and lower the wheel or segment below the machine’s clamping mechanism. This is a major cause of wheel/segment breakage.
Recessed Wheels (Type 5 & 7)
Wheels that have recesses cannot be worn down to their mounting flanges because the edge of the recess will “spall” away. A good rule of thumb for this type of wheel is to discard it when you are 1” away from the recess.
Portable Cup Wheels (Type 6 & 11)
In the case of a portable cup wheel, the proper guard will determine the discard size by preventing additional grinding on the wheel’s rim.
WARNING: Never remove a worn cup wheel from its proper grinder and use it on an inline grinder or any other machine. Never grind on the outer periphery of a cup wheel.
Cup Wheels for Precision Applications (Type 6 & 11)
Never allow contact with the cup wheel or allow the mounting flange assembly to contact the work piece holding fixture on fixed based machines with non-portable cup wheels.
WARNING: Maintain a safe distance to prevent accidental contact with the back of the cup or the mounting flange during grinding.
Raised Hub Wheels (Type 27, 29)
The proper guard for Type 27, 28 or raised hub wheels will often determine the wheel discard size. If the application allows the wheel to be worn to stub, you must stop before contacting the mounting flanges and should never use the wheel’s hub to grind.