Working with a grinding wheel can cause injury to the hands from cuts, to the eyes from debris or to the lungs from airborne dust particles. To protect against any of these potential injuries, the Occupational Safety and Health Administration (OSHA) has established several standards for workplace safety when using grinders.
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OSHA mandates safety guards for grinding wheels. The safety guard material and dimensions vary with wheel diameter, width and speed, and are specified in OSHA Standard 1910.215. Exceptions to this rule: wheels smaller than 2 inches in diameter on portable grinders; wheels inside the item when it is being ground; and grinders with a safety flange or other safety guards that completely protect the user do not require safety guards. OSHA standards also specify how much of the grinding wheel can be exposed to the user, depending on the type of machine and work. For bench grinders, no more than 90 degrees can be exposed to the user during grinding, for example. For the specific angle and diagrams for your application and grinder, consult standard 1910.215(b)(3) through (8).
To further protect the user, grinding wheels must be mounted between two equal-size flanges that cover at least one-third of the diameter of the wheel. Flange dimensions vary with the type of flange, wheel diameter and wheel thickness. Flanges must be maintained in good condition and balance, and replaced or refaced when needed. Blotters must also be used to evenly distribute flange pressure on the wheel. Some types of grinders do not require flanges and blotters.
OSHA standard 1910.215(d) covers the requirements for correctly mounting a grinding wheel. Before mounting, inspect the wheel for cracks and defects. To further check for unseen defects, perform a "ring test" on the wheel. Tap on the wheel with a non-metallic mallet or handle one to two inches from the outer edge and in 45-degree angles around the wheel. The wheel should make a ringing sound. If not, the wheel has a crack and should not be used. Next, check the spindle to be sure it does not exceed the safe operating speed for the wheel. When mounting, do not force the wheel onto the spindle and do not tighten the nut too tightly. The wheel should move freely. The surfaces on the flanges, wheel and blotter should be free of debris, and the flanges and blotter must fit flat and cover the wheel's surface completely.
Grinders must have enough power to rotate the wheel at normal, but not above, operating speeds. Always use eye protection when using a floor or bench grinder unless the grinder has attached eye guards and work rests.
A hooded exhaust system with dust collector must be used for ventilation when dust reaches the levels specified in the standard 1910.1000. These levels vary with the type of contaminate and exposure time. The required exhaust varies according to the type of grinder and size of the wheel, but can be found in OSHA standard 1910.94. No matter the size of the grinding operation, however, any exhaust system must be constructed to the standards of the American Standard Fundamentals Governing the Design and Operation of Local Exhaust Systems, also outlined in the OSHA standard 1910.94.
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- Occupational Safety and Health Administration: Abrasive Wheels and Tools, Standard 1926.303
- Occupational Safety and Health Administration: Abrasive Wheel Machinery, Standard 1910.215
- Occupational Safety and Health Administration: Ventilation, Standard 1910.94
- Occupational Safety and Health Administration: Air Contaminants