Subchapter 7. General Industry Safety Orders
Group 3. General Plant Equipment and Special Operations
Article 21. Use, Care, and Protection of Abrasive Wheels

§3575. Scope and Definitions.

2. Maximum hole size for cutting-off wheels should not be larger than 1/4-wheel diameter.

(B) Cylinder Wheels. Wheels having diameter, wheel thickness, and rim thickness dimensions. Grinding is performed on the rim face only, dimension W. Cylinder wheels may be plain, plate mounted, inserted nut, or of the projecting stud type.

Limitation: Rim height, T dimension, is generally equal to or greater than rim thickness, W dimension.

Limitation: Rim height, T dimension, is generally equal to or greater than rim thickness, W dimension.

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(C) Depressed Center Wheels. Have diameter, thickness and hole size dimensions. Both types are reinforced, organic bonded wheels having offset hubs which permit side and peripheral grinding operations without interference with the mounting. Type 27 wheels are manufactured with flat grinding rims permitting notching and cutting operations. Type 28 wheels have saucer shaped grinding rims.

1. Special supporting, back adapter and inside flange nuts are required for the proper mounting of these types of wheels.

2. Mounts which are affixed to the wheel by the manufacturer may not require an inside nut and shall not be reused.

(D) Depressed Center. Cutting-off Wheels, Type 27A. Wheels having diameter, thickness, and hole size dimensions. They are reinforced, organic bonded, offset hub type wheels, usually 16 inches diameter and larger, specially designed for use on cutting-off machines where mounting nut or outer flange interference cannot be tolerated.

(E) Flaring Cup Wheels. Wheels having double diameter dimensions D and J, and in addition have thickness, hole size, rim and back thickness dimensions. Grinding is always performed on rim face, W dimension. Type 11 wheels are subject to all limitations of use and mounting listed for type 6 straight sided cup wheels definition.

Limitation: Minimum back thickness, E dimension, should not be less than one-fourth T dimension. In addition when unthreaded hole wheels are specified the inside flat, K dimension, shall be large enough to accommodate a suitable flange.

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(F) Inorganic Wheels. Wheels which are bonded by means of inorganic material such as clay, glass, porcelain, sodium silicate, magnesium oxychloride, or metal. Wheels bonded with clay, glass, porcelain or related ceramic materials are characterized as "vitrified bonded wheels."

(G) Mandrel A steel shaft usually 3/8-inch diameter or smaller which is permanently secured to the abrasive section by cementing or other means. It is mounted in the machine and is the means by which the power is transmitted from the machine to the abrasive.

(H) Modified Types 6 and 11 Wheels (terrazzo). Some type 6 and 11 cup wheels used in the terrazzo trade having tapered K dimensions to match a special tapered flange furnished by the machine builder.

Limitation: These wheels shall be mounted only with a special tapered flange.

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(I) Mounted Wheels. Wheels which are usually 2 inches diameter or smaller, and of various shapes, and are permanently secured to a steel mandrel.

(J) Organic Wheels. Wheels which are bonded by means of an organic material such as resin, rubber, shellac, or other similar bonding agent.

(K) Straight Wheels. Wheels having diameter, thickness, and hole size dimensions, and they should be used only on the periphery. Type 1 wheels shall be mounted between flanges.

Limitation: Hole dimension (H) should not be greater than two-thirds of wheel diameter dimension (D) for precision, cylindrical, centerless, or surface grinding applications. Maximum hole size for all other applications should not exceed one-half wheel diameter.

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(L) Straight Cup Wheels. Wheels having diameter, thickness, hole size, rim thickness, and back thickness dimensions. Grinding is always performed on rim face, W dimension.

Limitation: Minimum back thickness, = dimension, should not be less than one-fourth T dimension. In addition, when unthreaded hole wheels are specified, the inside flat, K dimension, must be large enough to accommodate a suitable flange.

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Type 6 -Straight-cup Wheel Side grinding wheel having a diameter,thickness and hole with one side straight or flat and the opposite is derecessed. This type, however, differs from Type 5 in that the grinding is performed on the wall of the abrasive created by the difference between the diameter of the recess and the outside diameter of the wheel. Therefore, the wall dimension "W" takes precedence over the diameter of the recess as an essential intermediate dimension to describe this shape type.

Flanges. Collars, discs or plates between which wheels are mounted and are referred to as adaptor, sleeve, or back up type. See Section 3579.

Off-hand Grinding. The grinding of any material or part which is held in the operator's hand.

Portable Grinding. A grinding operation where the grinding machine is designed to be hand held and may be easily moved from one location to another.

Protection Hood. A protection hood is an enclosure for an abrasive wheel consisting of a peripheral and two side members. Its main function is to effectively retain the pieces of the wheel should the wheel break in operation.

Reinforced Wheels. A class of organic wheels which contain strengthening fabric or filament. The term "reinforced" does not cover wheels using such mechanical additions as steel rings, steel cup backs or wire or tape winding.

Safety Guard. An enclosure designed to restrain the pieces of the abrasive wheel in the event that the wheel is broken while in operation.

Snagging. Grinding which removes relatively large amounts of material without regard to close tolerances or surface finish requirements.

Surface Feet per Minute (s.f.p.m.). The distance in feet any one abrasive grain on the peripheral surface on a grinding wheel travels in 1 minute.

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Tuck Pointing. Removal of cement, mortar, or other non-metallic jointing material from masonry mortar joints and pointing up the tuck or joint.

Tuck Pointing Wheels. Tuck pointing wheels, usually Type 1, reinforced organic bonded wheels have diameter, thickness and hole size dimension. They are subject to the same limitations of use and mounting as Type 1 wheels.

Note: Wheels used for tuck pointing should be reinforced, organic bonded.

Note: Authority cited: Section 142.3, Labor Code. Reference: Section 142.3, Labor Code.

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