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

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

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

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