Safety Requirements for Using Abrasive Cup Wheels

Abrasive cup wheels are a fast, convenient way of grinding and cutting, but you must use caution and plan ahead like any cutting tool. By following OSHA and ANSI safety standards, you can be sure you are doing the job the right way and preventing costly accidents. The investment you make early on to learn and apply basic safety precautions pays off in a safer work environment. The following information is what you should know about using an abrasive cup grinder:

Cup Wheel Speed vs. Machine Speed

Every cup wheel has a maximum operating speed marked on it. Only mount the cup wheel on a machine with a speed no greater than the wheel's maximum operating speed. Never mount a cup wheel on a grinder that operates at a higher speed than the rated speed of the wheel.  

You also need to make sure the grinding machine has a proper back flange and guard. A proper guard extends far enough to keep debris and sparks away from your fingers and hands (see photo above). A proper back flange is flat across the entire contact surface in order to provide support for the cup. Its diameter is also at least one-third that of the wheel. ANSI B7.1 calls for minimum back flange sizes as follows:

Cup Wheel Mounting Checklist

• Check the wheel storage area to be sure the wheel has been properly stored in its original package, on a shelf, and away from moisture and temperature extremes.
• Visually inspect all of the abrasive cup wheels you plan to use and their packaging for damage. Never use a damaged abrasive cup wheel.
• Disconnect the machine from its power source before mounting or dismounting an abrasive cup wheel.
• Inspect the machine and its wheel guard. Never use a damaged machine or guard.
• Inspect and clean the machine’s back flange and mounting threads.
• When mounting or using an abrasive cup wheel, always follow the machine builder’s and wheel manufacturer’s safety instructions.
• Thread the wheel on the machine and hand tighten. Don’t excessively tighten the wheel - removal will be difficult and the wheel could be damaged during removal.
• Wear all required personal protective equipment such as eye, face, hearing, and respiratory protection as well as gloves, aprons, arm guards and safety shoes.
• Once a wheel has been mounted, test the machine and wheel by running it in an enclosed area such as in a steel drum for 60 seconds. During the test, keep yourself and your co-workers in a safe area. If there are any unusual vibrations or noises, do not use the wheel to grind.

Using Abrasive Cup Wheels

After you have mounted the cup wheel, follow these best practices to ensure a smooth and safe operating process:

• Never grind on the outside of a cup wheel.
• Never abuse the wheel; don’t bump or drop it. If a wheel looks damaged, remove and discard it.
• Always introduce the wheel to the work gently. Don’t jam the wheel into the workpiece or “force grind” so that the grinder motor slows noticeably.
• Always store wheels and machines with care between uses. Damage can occur from a drop or other impact just as easily as from improper grinding technique.
• Always repeat the startup sequence when you get back to work, even if you were just grinding five minutes ago – something may have been misaligned while you were away from the workbench.
• Always pay attention. Never drift away or allow yourself to get distracted while grinding, as the cup wheel can break if not used properly.

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.