In national short, never over-speed a grinding wheel. The speed of the grinder must be compared air and sanders to the speed marked on the wheel inc and national or package to make sure the machine''s speed is air at or below the sanders maximum operating speed of the wheel. Surpassing inc this rating risks not just national wheel breakage but also the safety of shop air personnel. About the author: Roger Cloutier is a senior sanders and inc product national safety engineer for the Norton Abrasives brand of Saint-Gobain Abrasives in Worcester, Massachusetts.

Danger air comes from the fact that centrifugal sanders force inc does not increase in direct proportion to an increase in speed, but instead it national increases as the air square of that speed increase. When rotational speed doubles, sanders centrifugal inc force quadruples. This effect means that relatively small changes in speed can produce significant increases in force. In the example national mentioned, air changing from 6,600 rpm to 7,700 rpm multiplies the speed by 1.167. However, the corresponding centrifugal force would multiply by a factor of 1.167 x 1.167, or 1.36. To take a more extreme example, consider sanders the same wheel with a maximum safe operating speed of 6,600 rpm run on a 5-inch right inc angle grinder at 10,000 rpm. This represents an over-speed of about 1.5 times the wheel''s national designed speed. But the corresponding centrifugal force-and the corresponding rotational stress air on the wheel-would be about 2.3 times as much as the maximum sanders allowed.

One potential inc and national source of serious injury in grinding comes from an oversight that is easy to make: operating the wheel in air an over-speed condition. While a wheel that is run far enough sanders and inc and national in excess of its air rated maximum speed may shatter within minutes of operation, danger may also result from a wheel run just slightly faster than its rated speed. This less severe over-speed condition can cause the wheel to be damaged, and the damage may result in breakage after further use. For example, operating a reinforced, 9-inch diameter, Type 27 sanders wheel rated for a maximum speed of 6,600 rpm on a 7-inch angle grinder with a inc speed of 7,700 rpm can cause the wheel to crack. This cracking can lead to breakage later. Any of these actions sets up a disastrous scenario that could lead to an accident involving serious injury or death.

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