When is a Grinding Wheel Worn Out?

Last reviewed by the Product Safety Team in December of 2024.

GOING, GOING, GONE!

We are often asked the question, "When is a grinding wheel worn out?" The answer depends on the grinding wheel and the application. Listed below are some of the most common types of grinding wheels and the answer to this question.

Type 1 (Straight Wheels)

ANSI B7.1 states, “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 that the proper flanges are used and the correct machine guarding is in place. WARNING: Do not grind with the fine center or core of any wheel. These are not designed for grinding. These centers may also contain steel rings, which can damage the grinding machine if contacted.

Type 2 or Cylinder Wheels and Segments

The machine will determine the discard size i.e. the down-feed mechanism will keep the wheel from contacting the workpiece. WARNING: Always use proper mounting procedures when using this type of product. Do not loosen the mount and lower the wheel or segment below the machine’s designed clamping mechanism, i.e. clamping mechanism must have complete contact with wheel or segment. This is a significant cause of wheel/segment breakage.

Type 5 & 7 (Recessed Wheels)

Wheels that have recesses CANNOT be worn down to their mounting flanges because the edge of the recess will “spall” away. For Types 5 & 7 recessed wheels, factors such as wheel grit size, application and experience will provide the user with the best answer. If you do not know, discard the wheel when you are 1” away from the recess.

Type 6 & 11 (Portable Cup Wheels)

Portable cup wheels must be discarded when the machine’s guard prevents proper grinding. In this case, a proper guard will determine discard size by preventing additional grinding on the wheel’s rim. WARNING: Never remove a worn cup wheel from its suitable grinder and use it on an inline grinder or any other machine. Never grind on the outer periphery of a cup wheel!

Type 6 & 11 (Cup Wheels for Precision Applications i.e. Fixed Based Machines)

On fixed-based machines with non-portable cup wheels, never allow contact with the back of the cup wheel or allow the mounting flange assembly to contact the workpiece holding fixture. WARNING: Maintain a safe distance to prevent accidental contact with the back of the cup or the mounting flange during grinding.

Type 27, 29 or Raised Hub Wheels

As with portable cup wheels, 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 a stub, stop grinding before contacting the mounting flanges and do not use the wheel’s hub to grind.

Type 16, 17, 18, 19 and 52 (Cones, Plugs, Mounted Points, and Mounted Wheels)

These products usually don’t require guards and aren’t mounted between flanges, which allow users to gauge usage duration. To avoid spindle contact during grinding, monitor product wear, spindle dimensions, and grit size. Discard the product when it is 3/16 inches from the spindle diameter for 36-grit and coarser products and 1/8 inch for 46-grit and finer products.
 

For additional information on this topic or if you need any other abrasive safety information, please review the Norton Product Safety page, ANSI, OSHA, and all literature provided by the abrasive wheel and machine manufacturer. You may contact the Saint-Gobain Product Safety Department at (508) 795-2317, or contact your Saint-Gobain Abrasives representative with any safety related questions.