437-004-2100 Grinders (1) Scope — These rules apply to all grinders except: (a) Standards for portable, hand-held power-driven grinders are in OAR 437-004-2230, Division 4/P. (b) Natural sandstone wheels. (c) Metal, wooden, cloth or paper wheels or discs with a layer or layers of abrasive on the surface. (2) Definitions. (a) Abrasive Wheel — cutting device made of abrasive grains held together by organic or inorganic bonds, including diamond and reinforced wheels. (b) Off-hand Grinding — The grinding of anything held in the operator’s hand. (c) Portable Grinding — A grinding operation where the grinding machine is hand held and easily moved from one place to another. (d) Safety Guard — An enclosure for an abrasive wheel. It has a peripheral and two side members. Its purpose and design is to contain the pieces of the wheel if the wheel breaks while in use. (3) Use. (a) Mount grinders securely on the floor, bench, foundation or other structure. (b) Do not use grinders that vibrate or are out of balance. (c) Do not use abrasive wheels that are out of round or out of balance. (d) Off-hand grinding machines must have work rests that are: (A) Rigid and adjustable to compensate for wheel wear. (B) Kept adjusted to within 1/8 inch of the wheel to prevent work from jamming between the wheel and the rest. (C) Securely tightened after each adjustment. (e) Do not adjust a moving wheel. (f) Do side grinding only on wheels designed for that purpose. NOTE: Dressing on the side of straight wheels is acceptable only with very light pressure. (4) Mounting. (a) Assure that grinding wheels fit freely but not loosely on the spindle, sleeves or adapters and remain free under all grinding conditions. (b) Do not operate an abrasive wheel designed to be held by flanges unless it is properly mounted between suitable flanges. Flanges must be at least 1/3 the diameter of the wheel, except for those types requiring flanges of a special design. (c) Install blotters (compressible washers) between flanges and abrasive wheel surfaces to insure uniform distribution of flange pressure. (d) Properly position the safety guard after mounting a wheel. (e) Run the grinder at operating speed after mounting an abrasive wheel with the safety guard in place or in a protected enclosure for at least one minute before using it. Keep employees away from the front of the wheel during this time. (f) Do not use wheels larger than those recommended by the manufacturer. (5) Safety guards. (a) Use abrasive wheels larger than 2 inches in diameter only on machines with safety guards. (b) These do not require safety guards: (A) Specially-shaped abrasive wheels mounted in a mandrel-type bench or floor stand and used for and commonly known as “sickle grinding stones or wheels.” (B) Abrasive wheels where the work itself provides full protection but only while the wheel is within the area of protection. NOTE: Abrasive wheel safety guards must meet the design specifications of the American National Standard Code for the Use, Care, and Protection of Abrasive Wheels (ANSI B7.1-1988). (c) Abrasive wheels that cover the spindle end, nut, and outer flange projection of the wheel must have guards. Guard the sides and periphery of the wheel except for that degree of exposure permitted below. (A) Bench and floor stands. (i) The maximum permissible angle of exposure is 90°. Begin this exposure at a point not more than 65° above the horizontal plane of the wheel spindle. (ii) Do not exceed 125° exposure where the nature of the work requires contact with the wheel below the horizontal plane of the spindle. Begin this exposure at a point not more than 65° above the horizontal plane of the wheel spindle. (B) Swing frame grinders. The maximum permissible angle of exposure is 180°. Enclose the top half of the wheel. (C) Top grinding. Do not exceed 60° exposure of the grinding wheel periphery where the work contacts the top of the wheel. (d) The peripheral protecting part of safety guards must adjust to compensate for wheel wear when the operator stands in front of the opening. (e) Maintain 1/4 inch between the wheel periphery and the adjustable tongue or the guard above the wheel. [Publications: Publications referenced are available from the agency.] Statutory/Other Authority: ORS 654.025(2) & 656.726(3) Statutes/Other Implemented: ORS 654.001 - 654.295 History: OSHA 4-1998, f. 8-28-98, cert. ef. 10-1-98