Proper storage, selection, and operating procedures for portable grinding operations help prevent safety hazards.
Material, hard and sharp enough to slice through metal, can break apart into jagged pieces that fly through the air at 200 miles an hour. It's a danger-ous—even life threatening—scenario caused by improperly using grinding wheels. But simple precautions recommended by the industry can help ensure safe grinding.
Before the job begins
Wheels not stored correctly can suffer damage that goes undetected until the wheel is used. To avoid damage, store wheels so that one can be removed without disturbing the other wheels; rotate wheel stock regularly to minimize possible damage; and store wheels away from water, solvents, extreme cold, or high humidity that causes condensation.
The right tool for the job
It is important to match grinding wheel sizes and operating speeds to the intended machine. For the best results, users should consult with the abrasives manufacturer. However, a few basic guidelines for wheel selection can be seen in the "Guidelines for selection" box.
Once the right wheel is determined, it should be well guarded. In 1994, "failure to provide or to require the use of a sufficient en-closure around an abrasive wheel" was the seventh most often cited OSHA safety violation.
Safe operating procedures
Unplug the machine before removing a worn grinding wheel and replacing it with a new one. Carefully inspect the new wheel for damage. Check to be sure that wheel speed does not exceed the machine speed. Make sure flanges are clean and in good condition.
Commonly used wheels such as a Type 27 mount easily with a reusable kit mount, which includes a back flange, a bottom flange, and an Allen wrench.
Once the wheel is mounted and the guard has been adjusted, place the wheel in a barrel or other enclosed area and allow it to run for one minute. If the wheel was damaged in transportation or handling, it will break safely in the enclosure.
When grinding, be sure to use the proper surface on the wheel. For example a Type 27 wheel's grinding surface is on the bottom of the wheel, not the top.
Allow wheels to come to a complete stop after grinding, and place them in a safe storage rack. Never drop the wheel or lay it down on any surface where it could be knocked on the floor. As soon as a wheel becomes worn, disconnect the power source, carefully remove the wheel, and begin the process again.
ANSI recommends electric grinders receive monthly checkups and that pneumatic machines be checked after 20 hr. of operation or once a week.
During inspection it is critical to also check the machine to en-sure it is running wheels at the proper, safe speed.
Machine speed is checked using a photo or contact tachometer. Record the speed along with the machine's serial number and date. The speed recorded must be less than or equal to the grinder's specified speed. By keeping careful logs, users can detect any speed changes over time.
Guidelines for selection
DO choose a wheel specifically designed for the machine in use