While abrasive wheels make it possible to cut, grind and shape hard materials like granite and limestone, the speed and force needed to change the shape of stone can turn deadly if the wheel explodes mid-job. Fine cracks in abrasive wheels can be almost impossible to see by the naked eye, making them easy to miss. Cracked or otherwise damaged wheels can explode when they contact ceramics at full speed. Further, bits of shattering wheel can fly from machines at high speed and pose a significant safety hazard. Inspecting and testing an abrasive wheel prior to mounting it on a machine greatly reduces the risk of breakdown and potential injury.
Clean any debris or residue from the surface of the wheel. Examine the wheel visually for any damage. Reject wheels that show signs of cracking or chipping.
Slip a finger into the wheel's spindle hole and lift it. Suspend the wheel in the air with your finger, letting the wheel hang perpendicular to the ground. Rest the bottom edge of the wheel lightly on the ground if it is a heavy model.
Look for the vertical centerline running through the middle of the wheel. Point the centerline straight upwards. Turn the wheel 45 degrees.
Tap the side of the hanging wheel directly over the center spindle hole, about 1 to 2 inches from the outer edge, with the rear end of a screwdriver. Use a rubber mallet rather than a screwdriver for especially large wheels. Listen for a clear, ringing tone.
Turn the wheel 45 degrees. Tap the wheel again in this new spot.
Continue rotating and tapping the wheel until you've gone around the entire diameter and reached the wheel's centerline once again. Do not tap the centerline on either side of the spindle as it will sound different from the rest of the wheel.
Reject any wheel that sounds hollow and dead when tapped. What you should hear is a clear ringing sound. Reject any wheel that sounds different than the other wheels manufactured in the same lot.