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UNITED STATES DEPARTMENT OF LABOR W ILLIAM N. DOAK, Secretary BUREAU OF LABOR STATISTICS ETHELBERT STEWART, C om m issioner BULLETIN OF THE UNITED STATES \ BUREAU OF LABOR STATISTICS / SAFETY CODE * * * • No. 527 SERIES SAFETY CODE FOR THE USE CARE, AND PROTECTION OF ABRASIVE WHEELS INTERNATIONAL ASSOCIATION OF INDUSTRIAL ACCIDENT BOARDS AND COMMISSIONS AND GRINDING WHEEL MANUFACTURERS ASSOCIATION, SPONSORS AMERICAN STANDARD Approved June 25, 1930 A m erican Standards A ssociation DECEMBER, 1930 UNITED STATES GOVERNMENT PRINTING OFFICE WASHINGTON s 1930 For sale by th e Superintendent o f D ocum ents, W ashington, D. C. - Price 10 cents CONTENTS Page Introduction____________________________________________________ 1 Section I.—Scope and definitions----------------------------------------------------Rule 1.1. Scope_____________________________________________ 1.2. Definitions_________________________________________ 4, 5 4 4, 5 Section II.—Types of protection devices____________________________ Rule 2.1. General requirements________________________________ 5 5 Section III.—Storage and inspection of wheels----------------------------------Rule 3.1. Storage____________________________________________ 3.2. Inspection_________________________________________ 5; 6 5 5; 6 Section IV.—General machine requirements. ------------------------------------Rule 4.1. Rigidity, supports----------------------------------------------------4.2. Diameter of spindle-------------------------------------------------4.3. Limit stop_________________________________________ 4.4. Direction of spindle thread----------------------------------------4.5. Length of spindle thread-------------------------------------------4.6. Size of wheel holes__________________________________ 6-8 6 6; 7 8 8 8 8 Section V.—Protection hoods______________________________________ 8-15 Rule 5.1. General requirements________________________________ 8 5.2. Mounting and fastenings_____________________________ 8 5.3. Exposure—Bench and floor stands-------------------------------8 5.4. Exposure—Cylindrical grinders-----------------------------------9 5.5. Exposure—Surface grinders---------------------------------------9 5.6. Exposure—Swing-frame and portable grinders__________ 9 5.7. Exposure—Top grinding_____________________________ 9 5.8. Exposure adjustment________________________________ 9 5.9. Fixed members_____________________________________ 9 5.10. Inclosure requirements______________________________ 9 5.11. Dimensions for peripheral and side members------------------ 10; 11 5.12. Material specifications_______________________________ 12 5.13. Construction guide----- ------------- ------------------- ------------12 5.14. Connections______________________ ____ ____________ 12 5.15. Connecting members (specifications)----------------------------15 5.16. Dust exhaust provision_______________ ____ _________ 15 Section VI.—Work rests__________________________________________ 15; 16 Rule 6.1. Construction__________________ ______ ______ ______15 6.2. Adjustment---------------- --------------------------------------------16 m IV CONTENTS Page Section VII.—Protection for cups, cylinders, and sectional ring wheels__ Rule 7.1. General requirements________________________________ 7.2. Hoods_____________________________________________ 7.3. Chucks------------------------------------------------------------------7.4. Bands_____________________________________________ 16 16 16 16 16 Section VIII.—Flanges___________________________________________ 17-22 General______________________________________________________ 17 Rule 8.1. General requirements________________________________ 17 8.2. Material___________________________________________ 17 8.3. Finish and balance__________________________________ 17 8.4. Uniformity of diameter______________________________ 17 8.5. Recess_____________________________________________ 17 17 8.6. Contact___________________________________________ 8.7. Fit________________________________________________ 17 Straight flanges (where hoods are employed)_______________________ 17-20 Rule 8.8. Dimensions_______________________________________ _ 17-20 Protection flanges (where hoods are not employed)_________________ 20-22 Rule 8.9. General requirements________________________________ 20 8.10. Degree of taper_____________________________________ 20 8.11. Dimensions________________________________________ 20-22 Section IX.— Mounting___________________________________________22, 23 Rule 9.1. Inspection_________________________________________ 22 9.2. Fit________________________________________________ 22 9.3. Surface condition___________________________________ 22 9.4. Bushing___________________________________________ 22 9.5. Washers___________________________________________ 22, 23 9.6. Tightening of nut-----------------------------------------------------23 Section X.—Speed_______________________________________________ 23-25 Rule 10.1. Recommended and maximum speeds__________________ 23 10.2. Testing of high-speed wheels_________________________23, 24 10.3. Speed test________________________________________ 24 10.4. Speed adjustment control-----------------------------------------24 10.5. Peripheral speed converted to revolutions per minute___ 25 Section XI.—Operating rules and general data_______________________26, 27 Rule 11.1. Responsibility_____________________________________ 26 11.2. Inspection after breakage___________________________ 26 11.3. Replacing hood------------------------------------------------------26 11.4. Starting newTwheels________________________________ 26 11.5. Applying work_____________________________________ 26 11.6. Test for balance_________________________________ _ 26 11.7. Truing____________________________________________ 26 26 11.8. Wet grinding______________ _______________________ 11.9. Side grinding---------------------------------------------------------26 11.10. Dresser guards_____________________________________ 26 11.11. Grinding room_____________________________________ 27 11.12. Lubrication_______________________________________ 27 11.13. Check for wear......................................................................... 27 BULLETIN OF THE U. S. BUREAU OF LABOR STATISTICS n o . 527 WASHINGTON D e c e m b e r , 1930 SAFETY CODE FOR THE USE, CARE, AND PROTECTION OF ABRASIVE WHEELS INTRODUCTION The 1926 edition of this code had a very wide distribution, and it was undoubtedly recognized as the most authoritative publication on the subject available. Since its issue much progress has been made in the grinding-wheel industry, particularly in relation to the develop ment of the high-speed wheel and high-speed grinding. In 1926 the maximum speed for the vast majority of grinding wheels in use was 6,000 to 6,500 peripheral feet per minute. Synthetic resin and rubber bonded wheels were beginning to make themselves known, and it was recognized that they could be operated at higher speeds. Some provision for the guarding of high-speed grinding was made, but as the manufacture and use of this class of equipment grew it was realized that the specifications were not complete nor entirely satisfactory. In order to keep pace with this progress it was necessary to revise certain sections of the code. Actual breakage tests were conducted to determine the suitability of steel castings for use in high-speed pro tection hoods. Other tests were made to determine the proper pro portions for tapered flanges to be used with high-speed wheels. Other rules were carefully studied and notes made of those sections which needed revision or amendment. A meeting of the sectional committee was held on February 5, 1930, at which all of these changes were discussed and put into definite form. A letter ballot of the entire sectional committee indicated unanimous approval of the suggested revisions. These were subsequently ap proved by both sponsors. The revised code was approved by the American Standards Association, June 25, 1930. I t is interesting to note that although a great many changes have been made they are all in detail only. In other words, the same general principles apply now as in the past. The importance of proper wheels, correct mounting, suitable machines, careful operation, and proper speed are recognized as means of preventing wheel breakage, but as all of these things are dependent on human control it is con sidered essential th at some form of mechanical guard be employed at all times. 1 A SAFETY CODE FOR ABRASIVE WHEELS The sectional committee which approved the revised code consists of the following members: Name and address Chairman, L. W. Chaney. U. S. Bureau of Labor Statistics, Washington, D. C. H. L. Whittemore, U. S. Bureau of Standards, Washington, D. C. Prof. C.-E. A. Winslow, consulting hygienist, 62 Park Street, New Haven, Conn. H. Q. Ehret, director of safety Industrial Commission of Ohio, Columbus, Ohio. R. McA. Keown, engineer Industrial Commission of Wisconsin, Madison, Wis. John P. Meade, director Division of In dustrial Safety, Department of Labor and Industries, Boston, Mass. John Roach, Department of Labor, Trenton, N. J. John Campbell, Industrial Board, Harrisburg, Pa. Secretary, A. Rousseau, Norton Co., Worcester, Mass. F. R. Henry, Simonds-Worden-White Co., Dayton, Ohio. George W. Chormann, Carborundum Co., Niagara Falls, N. Y. John R. Kempf, Detroit Star Grinding Wheel Co., Ill Cavalry Avenue, De troit, Mich. C. W. Gwynn. Safety Grinding Wheel & Machine Co., Springfield, Ohio. L. L. Byers, The Abrasive Co., Philadel phia, Pa. H. W. Dunbar, Norton Co., Worcester, F. H. Elam, American Steel Foundries, 410 N. Michigan Avenue, Chicago, G. E. Sanford, General Electric Co., Schenectady, N. Y. Frank P. Brown, Brown & Sharpe Mfg. Co., Providence, R. I. F. M. Ward, Otis Elevator Co., Yon kers, N. Y. H. J. Weeks, American Steel & Wire Co., Cleveland, Ohio. Van B. Hunter, International Harvester Co., 606 S. Michigan Avenue, Chicago, 111. S. E. Whiting, Liberty Mutual Insur ance Co., Park Square Building, Bos ton, Mass. J. J. Sheridan, National Bureau of Cas ualty & Surety Underwriters, 150 William Street, New York, N. Y. W. Dean Keefer, National Safety Coun cil, 20 N. Wacker Drive, Chicago, 111. Walter B. Gardiner, 16 Fonda Avenue, Troy, N. Y. A. J. Gifford, Leland-Gifford Co., Wor cester, Mass. P. J. Conlon, Ninth Street and Mount Vernon Place NW., Washington, D. C. George J. Speidel, 90 Elmora Avenue, Elizabeth, N. J. Association, society, or firm rep resented Sectional committee group U. S. Department of Labor....... Federal Government. U. S. Bureau of Standards__ Do. U. S. Public Health Service- Do. I. A. I. A. B. C. and Industrial Commission of Ohio. I. A. I. A. B. C. and Industrial Commission of Wisconsin. State regulatory bodies. Do. I. A. I. A. B. C. and Department Do. of Labor and Industry of Mas sachusetts. I. A. I. A. B. C. and Department Do. of Labor of New Jersey. I. A. I. A. B. C. and Depart Do. ment of Labor and Industry of Pennsylvania. Grinding Wheel Manufacturers Manufacturers of equipment Association and Norton Co. concerned (grinding wheels and grinding machines). Grinding Wheel Manufacturers Do. Association and SimondsWorden-White Co. Grinding Wheel Manufacturers Do. Association and Carborundum Co. Grinding Wheel Manufacturers Do. Association and Detroit Star Grinding Wheel Co. Grinding Wheel Manufacturers Do Association and Safety Grind ing Wheel & Machine Co. Grinding Wheel Manufacturers Do. Association and The Abrasive Co. National Machine Tool Build Do. ers’ Association. American Foundrymen’s Asso Employers as users of grind ciation. ing wheels. National Founders Association. Do. National Metal Trades Associa tion. Otis Elevator Co........................ Do. American Steel & Wire Co........ Do. International Harvester Co___ Do. Do. National Association Mutual Insurance interests. Casualty Cos. and Liberty Mutual Insurance Co. National Bureau of Casualty & Do. Surety Underwriters. National Safety Council............ General interests. American Society of Mechanical Engineering and technical Engineers. bodies. Societyof Automotive Engineers. Do. International Association of Ma chinists. Do. Metal Polishers, Buffers, and Employees as users of equip Platers of North America. ment. SAFETY CODE FOR ABRASIVE WHEELS Grinding Wheel Manufacturers Association of the United States and Canada The Abrasive Co., Philadelphia, Pa. American Emery Wheel Works, Provi dence, R. I. Brantford Grinding Wheel Co. (Inc.), Brantford, Ontario, Canada. Bridgeport Safety Emery Wheel Co., Bridgeport, Conn. Carborundum Co., Niagara Falls, N. Y. Chicago Wheel & Mfg. Co., Chicago, 111 . Cortland Grinding Wheel Corporation, Chester, Mass. A. P. DeSanno & Son, Philadelphia, Pa. Detroit-Star Grinding Wheel Co., Detroit, Mich. Hampden Grinding Wheel Co., Spring field, Mass. Lion Grinding Wheels (Ltd.), Brockville, Ontario, Canada. Macklin Co., Jackson, Mich. National Grinding Wheel Co., North Tonawanda, N. Y. Norton Co., Worcester, Mass. Norton Co. of Canada (Ltd.), Hamil ton, Ontario, Canada. Pittsburg Grinding Wheel Co., Roches ter, Pa. Precision Grinding Wheel Co., Phila delphia, Pa. Safety Grinding Wheel & Machine Co., Springfield, Ohio. Sterling Grinding Wheel Co., Tiffin, Ohio. Simonds-Worden-White Co., Dayton, Ohio. Vitrified Wheel Co., Westfield, Mass. Waltham Grinding Wheel Co., Wal tham, Mass. Wolf's New Process Abrasive Wheel Co., Meriden, Conn. International Association of Industrial Accident Boards and Commissions Virginia Industrial Commission. Washington Department of Labor and United States Bureau of Labor Sta Industries. tistics. West Virginia Workmen’s Compensa United States Employees’ Compensa tion Department. tion Commission. Wisconsin Industrial Commission. Arizona Industrial Commission. Wyoming Workmen’s Compensation California Industrial Accident Com Department. mission. Department of Labor of Canada. Connecticut Board of Compensation New Brunswick Workmen’s Compen Commissioners. sation Board. Delaware Industrial Accident Board. Nova Scotia Workmen’s Compensation Georgia Industrial Commission. Board. Idaho Industrial Accident Board. Ontario Workmen’s Compensation Illinois Industrial Commission. Board. Indiana Industrial Board. Quebec Workmen’s Compensation Iowa Workmen’s Compensation Serv Commission. ice. Kansas Commission of Labor and Associate M embers Industry. Maine Industrial Accident Commis George E. Beers, attorney and coun sion. selor at law, New Haven, Conn. Maryland State Industrial Accident Walter F. Dodd, Yale University Commission. School of Law, New Haven, Conn. Massachusetts Department of Indus E. I. Du Pont de Nemours & Co., Wilmington, Del. trial Accidents. Minnesota Industrial Commission. I. K. Huber, Empire Cos., Bartlesville, Okla. Montana Industrial Accident Board. Nevada Industrial Commission. Industrial Accident Prevention Asso New Jersey Department of Labor. ciations, Toronto, Ontario, Canada. New York Department of Labor. Leifur Magnusson, American Repre North Carolina Industrial Commission. sentative International Labor Office, North Dakota Workmen’s Compensa Washington, D. C. tion Bureau. Porto Rico Industrial Commission. Ohio Industrial Commission. Province of Quebec Safety League, Oklahoma State Industrial Commis Montreal, Quebec, Canada. sion. Republic Iron & Steel Co., Youngs Oregon State Industrial Accident Com town, Ohio. mission. J. F. H. Wyse, Canadian National Pennsylvania Department of Labor and Safety League, Toronto, Ontario, Industry. Canada. Utah Industrial Commission. Active M embers 4 SAFETY CODE FOR ABRASIVE WHEELS SECTION L—SCOPE AND DEFINITIONS 1.1. Scope. This code is intended to give rules and specifications which are necessary to insure safety in the use of abrasive wheels operating at peripheral speeds exceeding 2,000 feet per minute. 1.2. Definitions. Shall and should.—The word “ shall” where used is to be under stood as mandatory and “ should” as advisory. Abrasive wheel.—An abrasive wheel is a power-driven wheel con sisting of abrasive particles held together by artificial or natural mineral or .organic bonds. Metals, wooden, cloth, or paper wheels or discs having a layer or layers of abrasive on the surface are not included. Protection hood.—A protection hood is an inclosure for an abrasive wheel consisting of a peripheral and two side members. Its main function is effectively to retain the pieces of the wheel should it break in operation. Cast hood.—A cast hood is a protection hood which has the periph eral protecting member cast integral with at least one side member, and may be made of gray-iron castings, malleable-iron castings, or steel castings. Fabricated hood.—A fabricated hood is a protection hood which is built up or constructed by bolting, pinning, riveting, or welding the peripheral protecting member to the side members, and may be made of structural steel plate, wrought-iron plate, or an assembly of either of these in combination with gray-iron castings, malleable-iron cast ings, or steel castings or a material possessing an equivalent tensile strength. Flanges.—Flanges are collars, discs, or plates between which wheels are mounted. There are two main classes of flanges, namely, those intended for use in connection with protection hoods and those intended for use where protection hoods are not employed. The former serve only as a support and driving medium for the wheel while the latter serve as protection devices in addition. A separate definition for protection flanges is given below. Adaptors.—Adaptors are a form of flange used to mount wheels where the wheel hole is larger than the machine arbor. Sleeves.—Sleeves are a form of flange used on precision grinding machines where the wheel hole is larger than the machine arbor/ Usually the sleeve type of mount is so designed th at the wheel, the sleeve, and the flange can be assembled as a unit for convenience in changing wheels. Protection flanges.—Protection flanges or safety collars are flanges used with abrasive wheels of special shape, so designed th at in addition to the usual function of clamping the wheel to the spindle they will also serve to effectively retain the pieces of the wheel should it break in operation. Protection flanges are of several types, of which the following are the most commonly used: “ Tapered flanges,” sometimes called safety, beveled, or con cave flanges or collars, which are used with wheels having convex sides. SAFETY CODE FOR ABRASIVE WHEELS 5 “ Hub flanges,” which are used with wheels having a raised hub or hubs. “ Ring flanges,” having concentric ring or rings projecting from the bearing sides of the flanges, which fit into corresponding grooves in the sides of the wheels. Protection band— A protection band is a continuous band placed around a cup, cylinder, or sectional ring wheel to effectively retain the pieces of the wheel should it break in operation. Protection chuck.—A protection chuck is a chuck used for mounting cup, cylinder, or sectional ring wheels, so designed th at in addition to supporting and driving the wheel it will also serve to effectively retain the pieces of the wheel should it break in operation. Precision grinding.—This term includes grinding performed on types of machines commonly employed to produce perfection in dimensions and finish, as opposed to those grinding operations which are for the purpose of removing stock only. SECTION II.—TYPES OF PROTECTION DEVICES 2.1. General requirements. All abrasive wheels shall be provided with one of the following forms of protection. (a) Protection hoods. (b) Protection flanges. (c) Protection bands. (<d) Protection chucks. E x c e p t i o n .—This requirement shall not apply to wheels used for internal grinding, nor to wheels three inches or less in diameter running at a peripheral speed not exceeding 3,000 feet per minute. Forms (c) and (d) apply to cups, cylinders, and sectional ring wheels; forms (a) and (6) to all other shapes of wheels. SECTION III.—HANDLING AND STORAGE 3.1. Storage. Extreme care should be exercised in the storage of wheels. Suitable racks or bins should be provided to accommodate the various types of wheels carried in stock. Most straight and tapered wheels are best supported on edge in racks. Thin rubber, shellac, and other organic bonded wheels should be laid flat on a plane surface to prevent warpage. Cylinder wheels and large cup wheels should be stacked on the flat sides with corrugated paper or other cushioning material between them. Small cup and other shape wheels, also small internal grinding wheels, may be stored in boxes, bins, or drawers. Very large wheels can well be stored in original containers. 3.2. Inspection. Immediately upon receipt, all wheels should be closely inspected to make sure th at they have not been injured in transit or otherwise. As an added precaution, wheels should be tapped gently (while suspended) with a light implement, such as the handle of a screw 11130°—30------2 6 SAFETY CODE FOR ABRASIVE WHEELS driver for light wheels, or a wooden mallet for heavier wheels. they sound cracked, they should not be used. If N ote.—Wheels must be dry and free from sawdust when applying the test, otherwise the sound will be deadened. It should also be noted that organic bonded wheels do not emit the same clear metallic ring as do vitrified and silicate wheels. SECTION IV.—GENERAL MACHINE REQUIREMENTS 4.1. Rigidity, supports. Grinding machines should be sufficiently heavy and rigid so as to minimize vibration. They should be securely mounted on substantial floors, benches, foundations, or other adequate structures. 4.2. Diameter of spindle. No wheel of larger diameter or greater thickness than specified in the following table shall be used on any machine of given spindle diameter. M inimum diameters of spindles for wheels of various diameters and thicknesses operating at speeds up to 7fl00 peripheral feet per minute Thickness of wheel—-inches Diameter of wheel in inches H H H H l m in m 2 2K 2H m 3 SH 3H 4 4H y> % % K % % 6. 9_. 16. 18. 20 . 24. 26. IK I* y* % 1 1 IK IK IK IX IX 1 1 IK IK IX IX IX s iS 1% 2 2K 2 2 2 2 2 2K 2K 2K 2K 2K 2K 2K 2K 2K 2K 2K 2K 3 2 2K 2K 3 N o t e .—For speeds exceeding 7,000 peripheral feet per minute, the spindle sizes shown in the above table are usually not adequate. Inasmuch as the proper spindle size is dependent upon m an y factors, such as general design of the machine, type of bearings, quality of materials and workmanship, a simple table is not practicable. Wheels larger than specified by the machine manufacturer should not be used on any given machine. WHEELS 30. 36. i k 1K IK 1K IK 1)4 IX 1H IK IX 1H IK IX 1H 1X i 4 % FOR ABRASIVE 10. 12. 14. K K K K 1 l 1 1 % % l l 1 IK i i 1 1 l i i 1 1 IK IK IK IK i i IK IK IK IK IK IK i i IK IK l.K IK IK IK 1K IK IK IK IK IK IK IK IK IK IK IX IX IX IK IK IK IX IX IX IX IX IX IK IK IK IX IX IX IX •IK IK IK l% 1% 1K IK 1% 1K IK IK 2 2 2 IK IK IK IK 2 2 2 2 2K % K % 1 % k % 1 % % i 1 1 7. 8. SAFETY *CODE Diameter of spindle—inches <1 8 SAFETY CODE FOB ABRASIVE 'W HEELS 4.3. Limit stop. Grinding machines should be provided with a stop or other means of limiting the maximum diameter of wheel which can be mounted. 4.4. Direction of spindle thread. Ends of spindles shall be so threaded that the nuts on both ends will tend to tighten as the spindles revolve. Care should be taken in setting up machines th at the spindles are mounted so th at they will revolve in the proper direction, else the nuts on the ends will loosen. N ote.—To remove the nuts, they should both be turned in the direction that the spindle revolves when the wheel is in operation. 4.5. Length of spindle thread. When the wheel is mounted the thread on the spindle shall extend beyond the nut both inside and outside. 4.6. Size of wheel holes. Allowance for mounting fit shall be made in the wheel hole and not in the wheel mount. The wheel mount shall be made to nominal size within commercial limits. SECTION V.—PROTECTION HOODS 5.1. General requirements. Hoods shall always be used with wheels which are not provided with protection flanges, bands, or chucks. F ig u r e 1 F igure 2 F igure 3 5.2. Mounting and fastenings. Hoods shall be so mounted as to maintain proper alignment with the wheels, and the strength of the fastenings shall exceed the strength of the hood. 5.3. Exposure—Bench and floor stands. The maximum angular exposure of the grinding wheel periphery and sides for hoods used on machines known as bench and floor stands should not exceed 90° or one-fourth of the periphery. This exposure shall begin at a point not more than 65° above the horizontal plane of the wheel spindle. (See fig. 1.) Wherever the nature of the work requires contact with the wheel below the horizontal plane of the spindle, the exposure shall not exceed 125°. This exposure shall begin at a point not more than 65° above and extend to a point not more than 60° below the horizontal plane of the wheel spindle. (See fig. 2.) SAFETY CODE FOR ABRASIVE WHEELS 9 5.4. Exposure—Cylindrical grinders. The maximum angular exposure of the grinding wheel periphery and sides for hoods used on cylindrical grinding machines shall not exceed 180°. This exposure shall begin at a point not more than 65° above the horizontal plane of the wheel spindle. (See fig. 3.) 5.5. Exposure—Surface grinders. The maximum angular exposure of the grinding wheel periphery and sides for hoods used on surface grinding machines which employ the wheel periphery shall not exceed 150°. (See fig. 4.) 5.6. Exposure—Swing frame and portable grinders. The maximum angular exposure of the grinding wheel periphery and sides for hoods used on machines known as swing frame and portable grinding machines shall not exceed 180°, and the top half of the wheel shall be protected at all times. (See fig. 5.) 5.7. Exposure—Top grinding. In operations where the work is ground on the top of the wheel, the exposure of the grinding wheel periphery shall be as small as practicable, with a maximum exposure of 60°. (See fig. 6.) 5.8. Exposure adjustment. Hoods shall be constructed so that the peripheral protecting mem ber can be adjusted to the constantly decreasing diameter of the wheel by means of an adjustable tongue, or its equivalent, so th at the angular protection specified in rules 5.3 to 5.7 will be maintained throughout the life of the wheel, and the maximum distance between the wheel periphery and tongue or end of peripheral band at top of opening will not exceed one-fourth inch. (See figs. 7, 8, and 9.) 5.9. Fixed members* Hoods shall be constructed so th at it is not necessary when chang ing wheels to detach the peripheral protecting member from the side member which is connected to the machine. 5.10. Inclosure requirements. The hood shall inclose the spindle end, nut, and flange projections, if any. E x c e p t i o n .—Protection hoods on cylindrical grinding machines, in all operations where the work provides a suitable measure of protec tion to the operator, may be so constructed th at the spindle end, nut, and flanges are exposed; and where the nature of the work is such as to entirely cover the side of the wheel the side covers of the guard may be omitted. 10 SAFETY CODE FOR ABRASIVE WHEELS 5.11. Minimum dimensions for the peripheral and side members. All members specified in this table may be used with wheels run ning up to 7,000 peripheral feet per minute. Showing adjustable tongue giv ing required angular protec tion for all sizes of wheels used. Showing movable hood with opening small enough to give required protection for smallest size wheel used. F igure 9.—Incorrect Showing movable hood with size of opening correct for full size wheel, but too large for smaller wheels. Steel casting hoods or hoods fabricated from structural steel, wrought iron, or steel castings as specified, or other types of construc tion affording equal protection, shall be used with wheels running between 7,000 and 10,000 peripheral feet per minute. E x c e p t i o n .—For cutting-off wheels (less than one-fourth inch in thickness) cast hoods made according to the following table may be used, even though the speed exceeds 7,000 feet per minute. Grinding wheel diameters Material used in construction of guard Inches 2 3 to 6 inches 7 to 12 inches 13 to 16 inches 17 to 20 inches 21 to 24 inches 25 to 30 inches 31 to 48 inches A A B X Me X Me X M. X Me X Me % *4 x X Materials satisfactory for speeds up to 10,000 peripheral feet per minute: Steel castings_____________________ Do__________________________ Do__________________________ 2 4 y* x 6 x Structural steel _____ ______________ Do_______________ _______•___ Do.......... ......................................... 2 4 6 Me Wrought iron_____________________ Do________________ _________ D o__________________________ 2 4 6 H H x Me X X X H % X X Me Me Me Me Me X % Me Me Me X Me X X X X X X % X X Me Me X X X Me X i % % IX % X X % Y* % % % X x X % X Me % X y* Me X Me X Me % X H X Me Me % Me Me Me Me Me X X X % $ X A Inches X % x B X % X Me B A Inches Inches % 1 % IX % IX % IX % % IX % % 1 X B 1 1 IK % ix M IX Y* % % % % Y* ft % Vs % 1 % ix % % % X Vs % Me Me X Me X Me X X X Me Me Me X Me % Me % > X % 1% % X X X X X X X X 11 X X Me WHEELS x 1 * FOR ABRASIVE X X A CODE ne X y* B Inchet X % X % % Inch X 2 4 6 Me A % Malleable iron____________________ Do__________________________ Do__________________________ Me B Me X X Me X Me X 4 6 A Inch Inch X B SAFETY Materials satisfactory for speeds up to 7,000 peripheral feet per minute: Cast iron_________________________ Do— ____ ___________________ Do_____ _____________________ Maximum thickness of grinding wheel 12 SAFETY CODE FOR ABRASIVE WHEELS 5.12. Material specifications. Materials used in the construction of hoods shall conform to and be in accordance with the following specifications of the American Society for Testing Materials: (a) Gray iron castings—A 48. (b) Malleable iron castings—A 47. (c) Steel castings—A 27 (class B medium). (<d) Structural steel plate—A 9 (excluding specifications for rivet steel). (e) Wrought iron plate—A 42 (class A). N o te .— Copies of these specifications may be procured at a nominal price from the American Society for Testing Materials, Philadelphia, Pa. 5.13. Construction guide. As a guide for the construction of fabricated hoods of steel plate or wrought iron the following drawings have been prepared. Other types affording equal protection are also acceptable. The requirements given in columns C, D, and E of this table shall apply also to cast hoods; and in such cases, where the tongue is held by bolts, column F shall also apply. C Diameter of wheel (inches) Under 12___ 12 to 16___ 17 to 24___ Over 24___ D E F G H J K Maximum Maxi Diam Diam space Length Diam between mum Size of angle eter of eter of Thick eter of supports for rivets end con ness of of new wheel inside bolts for and hood width of tongue tongue tongue and rest for sup necting tongue ports hood at periph bolts ery Inches lM 1H Inches 1 IX i2 i2 i2 Inches m 5 6 7 Inch Inches X 1y2 x i y2 x }i %6 %6 % 2 x 2 x fie 2 x 2 xy2 21/2 x 2 y2 x y2 Inch v™ H X Me Inch Vl6 X %e 5/s Inch y* Me X i Wider than wheel. 5.14. Connections. Connections between the peripheral and side members, or between parts of a sectional hood, shall have a strength in a radial direction at least equal to the strength of the members. SAFETY CODE FOR ABRASIVE WHEELS 0os/f/o/r Attjt/Sfob/e A6r# sty tforet Pus/ exAravjfovf/etjh&vAt\ be/eeaf&f/a/Av'posfttb* .tvhere /V w'//**#*/ f/fce&Wty remorvtfr**&*fi F igure 11.—For suction pipe sizes see rule 5.16 11130°—30------3 13 14 SAFETY CODE FOB ABRASIVE WHEELS £bs/f/arr Monet 04f<st**A*t/>sSov//e/jfrov/J 6e /ft f fa p o s itio n trA * r* ✓ / *rf///rtvs/ eftg cf/i* / y M*tfcsfi F igure 13.-—For suction pipe sizes see rule 5.16 F R O N T VI£W ,ALSO CROSS S E C T I O N S 5 HOW//VG F O U R S A T I S F A C T O R Y M ETHODS OF SECURING C O V E R * B S T h ese v ie w s HOTKi C om tshred s e c t i o n a l o r « a o f a n g le s t o a t l e a s t eqvo/ area of" peripheral a ll a p p ly S E C T IO N HUTS S H O W IN G - ANGLE ON CN05 ty p es A ,B * C H oa d s C o m b in e d s e c t i o n a l a r e a o f strops to a t l e a s t e q u a l t w i c e th e ' t o t a l a r e a o f b o l t s in o t h e r ♦ IN T O to Nore: BO LT W ELDED Types ? S F C O V E .F t H E L D B Y o r B O L T S - SECT/O N A N D S ID E V IE W SH O W IN O CO V E R H E L D G V W ED G E K E Y S TH RO UGH r L A T IROIV S T « ^ P 5 *"/?« v e t s v 3 £ C T /O N s h o w in g b o l t THREADED coveff IN TO A N G L E O N L Y ” H ELO B Y N U TS ON EN D S O F B O L T S - -f?,vets^ S E C T IO N SHO W ING S T U D T H R E A D E D fN T O A N G L E O N L Y - C O V E R H E L O B Y f**N$ T H R O U G H E N O S O f S T U O S - F igure 14 SAFETY CODE FOR ABRASIVE WHEELS 15 5.15. Connecting members (specifications). Minimum sizes and spacing of rivets, holts, and studs for connecting peripheral and side members in fabricated hoods of wrought iron and steel plate For side plate (B-l) attached to machine Thickness of plates being connected Inches and Vie z/t 6 and Me J4e and x/% Maximum of Maximum Diameter of distance Diameter distance bolts or between rivets between studs centers centers Inch Vs and K and Va and <K6 For detachable side plate (B-2) Vie Ke % % Inches 3 3 3 Inch Inches Vie 6 6 6 3 4 3H Vie M. %6 6 8 7 % % an d ^ and %6 He and ) i % Vio 3 4 4 Yu 13/l« % 6 8 8 and y4 y8 and %q y16 and K %e 4 3X 3 % 13/l« % 8 7 6 % %* %e and 5/ig y2 and % and % %e %o %6 3 3 3 % 'Vie 13/l6 6 6 6 Y& and % 1Me and J4& % % 3 3 % % 6 6 Ke 5.16. Dust exhaust provision. Hoods on machines used for dry grinding and other operations where dust is produced should have provision made for connection to an exhaust system. The size of such connections should be in conformity with the following specified dimensions: Diameter of wheel Minimum diameter of branch pipe 6 inches or less___________________________________ 3 inches 7 inches to 16 inches_______________________________ 4 inches 17 inches to 24 inches----------------------------------------------- 5 inches 25 inches to 30 inches----------------------------------------------- 6 inches A modification of the above requirements will be allowed in the case of narrow wheels used for light work where very little dust is generated and where a smaller pipe will satisfactorily remove it. The requirements in this paragraph shall not apply to swing frame and portable grinding machines. SECTION VI.—WORK RESTS 6.1. Construction. Work rests shall be rigid in construction. On operations where they are not used, they shall be removed from the operating position. 16 SAFETY CODE FOR ABRASIVE WHEELS 6.2. Adjustment. The work rest should be kept adjusted close to the wheel, with a maximum distance of one-eighth inch, to prevent the work from being caught between the wheel and rest, and should be securely clamped after each adjustment. This adjustment shall not be made while the wheel is in motion. The rest should be maintained in good condition. SECTION VIL—PROTECTION FOR CUPS, CYLINDERS, AND SECTIONAL RING WHEELS 7.1. General requirements. Cups, cylinders, and sectional ring wheels shall be either protected with hoods, inclosed in protection chucks, or surrounded with protec tion bands. N ot more than one quarter of the original height of such grinding wheels shall protrude beyond the provided protection. Where the thickness of the rim of such wheels is less than 2 inches, the maximum distance which the wheel may protrude beyond the provided protection shall not exceed a dimension equal to the thick ness of the rim. If the thickness of the rim is 2 inches or more, the wheel may protrude 2 inches beyond the protection but shall not exceed this amount. 7.2. Hoods. Where hoods are used, they shall conform to the specifications given in rules 5.1 to 5.16, inclusive, in this code. 7.3. Chucks. Where the chuck which holds the wheel is the only protection provided, it shall be so designed th at the jaws will at all times protect the wheel up to the point specified in rule 7.1. 7.4. Bands. Where protection bands are used, they shall conform to the follow ing specifications: (а) They shall be made of wrought iron or steel plate or other material oi equal strength, shall be continuous and bent to conform as closely to the periphery of the wheel as practical. The ends shall either be riveted, bolted, or welded together in such a manner as to leave the inside of the band free from projections. (б) The bands shall be of sufficient width to provide the protection specified in rule 7.1. (c) The thickness of the band shall be made according to the following table, which also shows the size and spacing for riveted joints. If bolting or welding is used, the strength of the connections shall be at least equal to the riveted joints specified in this table. Diameter of wheel Inches Under 8 ___ 8 to 2 4 ___ 25 to 3 0 __ Mini Thick mum ness of diam eter band of rivets Maximum dis tance be tween centers of rivets Inches Inches Inches Me H Yi % % i &■ SAFETY CODE FOR ABRASIVE WHEELS 17 SECTION VIII.—FLANGES GENERAL 8.1. General requirements. All abrasive wheels shall be mounted between flanges, excepting those which are mounted in chucks, cemented to metal backs, or otherwise securely and adequately mounted on swindles. These flanges (sometimes called collars) may be of the straight type (rule 8.8), the tapered type (rule 8.11) or of some other design affording at least equal support and protection. 8.2. Material. All tapered flanges over 10 inches in diameter shall be of steel. All other flanges may be made of cast iron, or other material of equal strength. 8.3. Finish and balance. Flanges shall be finished all over correct to dimensions and in balance. (The requirement for balance does not apply to so-called balancing flanges which are purposely made out of balance.) 8.4. Uniformity of diameter. Both flanges, whether straight or tapered, in contact with wheel, shall be of the same diameter. 8.5. Recess. Straight flanges made according to Figure 15 and tapered flanges made according to Figure 19 shall be recessed at least one-sixteenth of an inch on the side next to the wheel for a distance as specified in the respective tables of dimensions for straight and tapered flanges Straight flanges of the adaptor and sleeve types (figs. 16 and 17) shall be recessed so th at there will be no bearing on the sides of the wheel within one-eighth of the hole. 8.6. Contact. Bearing surfaces of flanges shall be so designed th at when tightened up full contact with wheel will be insured. 8.7. Fit. The driving flange shall be keyed, screwed, shrunk, or pressed onto the spindle, and the bearing surface shall run true and at right angles with the spindle. STRAIGHT FLANGES (Where protection hoods are employed) 8.8. Dimensions. Where protection hoods are used, sizes of straight flanges for straight wheels shall not be less than shown in the following tables, (figs. 15, 16, and 17.) Figure 15 shows the minimum dimensions for so-called straight flanges for use with straight sided wheels with small holes which fit directly on the machine arbor. (These are not protection flanges and shall only be used in connection with protection hoods which comply with Sec. V.) 18 SAFETY CODE FOR ABRASIVE WHEELS k c * ■ B F igure 15 A B c Diameter of wheel Minimum outside diameter of flanges Radial width of bearing surj[ace Minimum Inches 1_____ _ 2 _______ 3_____ 4_____ 5_____ 6 _______ Inch Yi < q H H Inches x k M. VA 1% 2 Ks % Vie fie 14____ 16____ 18____ m 5H Vs X yk 20_ 2 2 ______ 7 7J4 % % % % % % 1 6 24____ 8 26____ 28____ 30____ 10 10 36____ 12 8/2 Inch K« X % k H he 5/l6 10______ 12______ Maximum Inches % % 1 3 sy2 4 8 _______ E D Minimum Minimum thickness of thickness of flange at bore flange at edge of recess i l K X % % % % % % % X X % % % % % IK IK IK IK 1H m 2 ! Inch Vie %2 %2 X X %• Ke H Vu He % % At Jit H % % X % % H % Figure 16 shows the minimum dimensions for so-called adaptor flanges for use with straight-sided wheels with holes larger than the machine arbor. (These are riot protection flanges and shall only be used in connection with protection hoods which comply with Sec. V.) N o te .— These adaptors may be clamped together by means of a central nut, or by a series of bolts or some other equivalent means of fastening. 19 SAFETY CODE FOR ABRASIVE WHEELS Wheel diameter Inches \ 12 to 14_______ ____ I Larger than 14 to 18- Larger than 18 to 24. Larger than 24 to 36- E B D Minimum Minimum Minimum Hole flange thickness thickness diameter diameter of flange of flange at bore at edge of recess Inches Inches 4 5 6 6 7 8 % % % % 4 5 6 7 8 6 7 8 . 9 10 % % % % % % % % % 6 Vi % % 12 8 9 10 12 14 % H H H H 12 15 % % 7 8 10 Inch % % Inch % 3A Figure 17 shows the mininnim dimensions for so-called sleeve flanges used on precision grinding machines for mounting wheels with holes larger than the machine arbor. (These are not protection flanges and shall only be used in connection with protection hoods which comply with Sec. V.) a Figure 17.—Driving flange secured to spindle. See rule 8.7 N ote.—These flanges may be clamped together by means of a central nut, or by a series of bolts or some other equivalent means of fastening. 20 SAFETY CODE FOR ABRASIVE WHEELS B Wheel diameter Wheel hole Inches Inches 12 to 14___ 5 5 Larger than 14 to 20. 6 8 10 12 10 12 16 12 Larger than 30 to 36 _ 16 18 20 PROTECTION FLANGES E Minimum Minimum Minimum outsize thickness thickness of flange diameter of flange at edge of of flange at bore Inches 7 7 8 10 Inch % 5/? 11V2 1154 13V2 17/2 U% 17'K 19% 21H Inch 7/l6 Mg Vie He 13K 10 Larger than 20 to 30 J) 7Ao % h % % /* % a y* % ¥2 H (Where hoods are not employed) 8.9. General requirements. Protection flanges (also called safety collars) shall always be used with wheels 6 inches and larger which are not provided with hoods, chucks, or bands. (See rule 5.1.) Specifications follow for the tapered type only, which type should be used wherever possible. Other types affording at least equal protection are also acceptable. 8.10. Degree of taper. Tapered wheels should be tapered at least three-fourths inch per foot on each side. Tapered flanges or collars made according to Figure 19 and Figure 22 shall have the same degree of taper as the wheels. Tapered flanges or collars made according to Figure 21 shall be tapered one thirty-second inch per foot more than the taper of the wheel. 8.11. Dimensions. Where no hoods are used, the dimensions of tapered flanges or collars shall not be less than shown in the following tables. Two satisfactory types are illustrated (fig. 19 and fig. 21) for use with wheels operating not faster than 6,500 peripheral feet j)er minute. 21 SAFETY CODE FOB ABRASIVE WHEELS A Diam eter of wheel Inches 6 8 10 B c Mini mum outside diame ter of flanges Radial width of bearing surface, fig. 19 only Mini mum Maxi mum Inches Inches Inches Inch Inch H K« X % i % % *. X X i IX ix X X X Yi« X X X X X 4 4 4 5 6 4H 4/2 6 X X ^6 X X X 4 4 4 6 7 7 6 6 6 4 4 4 8 8 8 6 6 6 4 4 8 6 6 3 4 5 D E El X X Inch 12 14 16 8 10 X X X 18 20 22 12 14 16 1 IX IX 2 2% X X X 24 26 28 18 20 22 1X ix ix 3 3X 3X X X £ X % X X 30 36 24 28 2 2 4 4 X 1 3 /4 % X 6 F ig u r e 2% FI Inches 0 0 0 5 f :F ' ' ' p? i/JOt m r - F igure 19—For degree of taper see rule 8.10 F igu re Inches 18.—Driving flange secured to spindle. See rule 8.7 ^ F G Maxi Mini Mini Maxi Diam mum Minimum mum di mum mum at thick flat eter of ameter thick edge of ness at spot at flat area of flat ness of recess, bevel, center outside, spot or flange fig. 19 fig. 21 of flange fig. 21 hub of only at bore only inside only wheel 20.—Driving flange secured to spindle. See rule 8.7 Inches 1 1 2 22 SAFETY CODE FOB ABRASIVE WHEELS F igure 21.—For degree of taper see rule 8.10 Figure 22 shows the minimum dimensions of protection flanges for use with wheels operating faster than 6,500 peripheral feet per minute up to 9,500 peripheral feet per minute. — r *. * ---i — f— *• —: Af ^ VC * H ----- £ ------------------- F igure 22.—Driving flange secured to spindle. See rule 8.7. For degree of taper see rule 8.10 Diame- Thick eter of ness of wheel wheel In. 16 18 20 24 30 In. C B Mini In. In. mum In. 4 4 4 4 4 Maxi 10 12 14 18 24 1H 2 3 4 5 D E j In. In. K L In. In. 6 6 7 8 10 Vi M N In. In. In. i y,e % mum 1 2 3 3^2 § 1 ni l'A % % 1 154 l'A 2 r 4 i 1H 2 Ke % % % H H % SECTION IX.—MOUNTING 9.1. Inspection. Before mounting, all wheels shall again be closely inspected to make sure that they have not been injured in transit, storage, or otherwise. (See rule 3.2.) 9.2. Fit. Grinding wheels shall fit freely on the spindles; they should not be forced on, nor should they be too loose. (See rule 4.6.) 9.3. Surface condition. All surfaces of wheels, washers, and flanges in contact with each other should be free from foreign material. 9.4. Bashing. The soft metal bushing shall not extend beyond the sides of the wheel. 9.5. Washers. Washers or flange facings of compressible material shall be fitted between the wheel and its flanges. If blotting paper is used, it should 23 SAFETY CODE FOR ABRASIVE WHEELS not be thicker than 0.025 inch. If rubber or leather is used, it should not be thicker than one-eighth inch. If flanges with babbitt or lead facings are used, the thickness of the babbitt or lead should not ex ceed one-eighth inch. The diameter of the washers shall not be smaller than the diameter of the flanges. 9.6. Tightening of nut. When tightening spindle end nuts, care should be taken to tighten same only enough to hold the wheel firmly; otherwise, the clamping strain is liable to damage the wheel or associated parts. SECTION X—SPEED 10.1. Operating speed. The following table indicates maximum peripheral speeds for various types and grades of wheels. These speeds shall not be ex ceeded except upon the distinct recommendation of the grinding wheel manufacturer for each specific case, and then only if the user maintains his equipment in a condition satisfactory to the wheel manufacturer. Vitrified and silicate bonds Organic bonds Types of wheels Soft Medium Hard Soft Medium Hard F.p.m. F.p.m. F.p.m. F.p. m. F.p.m . F .p.m . 6.500 6.500 8,000 9, 500 6.500 6,000 6.500 6,000 8,000 8,000 9.500 9.500 6,000 6,000 8,000 9, 500 5.500 6, 000 7.500 9.000 6,000 7.500 9.000 10, 000 12, 000 f 12,000 | to [ 16,000 Type 1—Straight wheels 1___ Type 4—Taper wheels 1____ }5, 500 26, 000 Types 5 and 7—Recessed wheels1__ __ _______ 5.500 26, 000 Type 2—Cylinder wheels _ 4.500 5.500 Dovetail wheels 8__________ Types 11 and 12—Dish and j*, 500 5.500 flaring cup wheels.1 Type 13—Saucer wheels___ Type 6—Deep recessed cup wheels_________ _______ 4.500 5,000 Coping wheels (solid and steel centers)8___________ Type 1—Cut-off wheels (ordinary)1______ ____ _ Type 1—Cut-off wheels (special) (depending on stability and design of machine)_______________ 1 Standard shapes (Department of Commerce—Simplified Practice Recommendation R45-28). 2 On precision machines, vitrified and silicate wheels in medium grades may be operated at 6,500 periph eral feet per minute. 3Nonstandard shapes. N ote.— Maximum speeds indicated are based on the strength of the wheels and not on their cutting efficiency. Best speeds may sometimes be considerably lower. 10.2. Testing of high-speed wheels. No wheels shall be operated at speeds exceeding 6,500 peripheral feet per minute, which have not been tested at a speed at least 50 24 SAFETY CODE FOR ABRASIVE WHEELS per cent faster than the operating speed, with the following excep tions: (а) Cut-off wheels. (б) Wheels less than 8 inches diameter where product of square of diameter by thickness in inches is less than 80. (c) Wheels less than 6 inches diameter. When wheels of unusual and extreme shapes such as deep cups with thin walls or backs, long drums and so forth are required, consult the wheel manufacturer for speeds recommended. 10.3. Speed test. Machine spindle speeds shall be tested and determined correct for size of wheel to be operated, before the wheel is mounted and shall never be changed as wheel is reduced in diameter, except by men assigned for such duties. 10.4. Speed adjustment control. Where speed of wheel spindle is adjustable, speed adjustment shall be in control of authorized persons only. 10.5. Table of speeds. Revolutions per minute for various diameters of grinding wheels to give peripheral speed in feet per minute as indicated Peripheral speed in feet per minute Diameter of wheel in inches 4,000 10 12 14 16 18 20 22 868 796 734 682 637 597 562 530 R. p. m. 21, 008 10, 504 7, 003 5, 252 4,202 3, 501 3,001 2, 626 2, 101 1, 751 1, 500 1, 313 1, 167 1, 050 955 875 808 750 700 656 618 583 R. p. m. 22, 918 11, 459 7, 639 5, 729 4,584 3, 820 3, 274 2, 865 2, 292 1, 910 1, 637 1, 432 1, 273 1, 146 1, 042 955 881 818 764 716 674 637 6,500 R. p. m. 24, 828 12, 414 8,276 6,207 4,966 4,138 3,547 3, 103 2,483 2, 069 1, 773 1, 552 1, 379 1, 241 1, 128 1, 034 955 887 828 776 730 690 7,000 R. p. m. 26, 737 13, 368 8, 913 6,685 5,348 4, 456 3,820 3, 342 2,674 2, 228 1, 910 1, 672 1, 485 1, 337 1, 215 1, 115 1, 028 955 891 836 786 742 7,500 R. p. m. 28, 647 14, 328 9,549 7, 162 5,730 4,775 4,092 3,580 2, 865 2, 386 2, 046 1,791 1, 591 1, 432 1, 302 1, 194 1, 101 1, 023 955 895 843 795 8,000 R. p. m. 30, 558 15, 278 10, 186 7, 640 6, 112 5,092 4,366 3, 820 3, 056 2, 546 2, 182 1, 910 1, 698 1, 528 1, 388 1, 274 1, 176 1, 092 1, 018 954 898 848 8,500 R. p. m. 32, 467 16, 238 10, 822 8, 116 6,494 5, 411 4, 538 4,058 3, 247 2, 705 2, 319 2, 029 1, 803 1, 623 1, 476 1, 353 1, 248 1, 159 1, 082 1, 014 955 902 9,000 9,500 R. p. m. R. p. m. 34, 377 17, 188 11, 459 8,595 6,876 5,729 4,911 4, 297 3,438 2, 864 2, 455 2, 149 1, 910 1, 719 1, 562 1, 433 1, 322 1, 228 1, 146 1, 074 1, Oil 954 36, 287 18, 143 12, 115 9, 072 7,258 6, 048 5, 183 4,535 3, 629 3,023 2, 592 2,268 2, 016 1, 814 1,649 1, 512 1, 395 1, 296 1, 210 1, 134 1, 067 1, 007 WHEELS 24 26 28 30 32 34 36 R. p. m. 19, 098 9,549 6,366 4, 775 3, 820 3, 183 2, 728 2, 387 1, 910 1, 591 1, 364 1, 194 1, 061 955 6,000 FOR ABRASIVE 7. 8. R. p. m. 17, 189 8,594 5,729 4,297 3,438 2, 865 2, 455 2, 148 1, 719 1, 432 1, 228 1, 074 955 859 781 716 661 614 573 537 505 477 5,600 CODE 5 6 R. p. m. 15, 279 7, 639 5, 093 3, 820 3, 056 2, 546 2, 183 1, 910 1, 528 1, 273 1, 091 955 849 764 694 637 588 546 509 477 449 424 5,000 SAFETY 1 2 3 4. 4,600 N o t e .—“ Centrifugal force,” which is the force that tends to rupture a given wheel when overspeeding, increases as the square of the velocity of that wheel. For example, the centrifugal force in a wheel running at 5,500 surface feet per minute is 49 per cent greater than in the same wheel running at 4,500 surface feet per minute, although the speed is actually only 22 per cent greater. fcO Or 26 SAFETY CODE FOE ABRASIVE WHEELS SECTION XI.—OPERATING RULES AND GENERAL DATA 11.1. Responsibility. Competent men shall be assigned to the mounting, care, and in spection of grinding wheels and machines. 11.2. Inspection after breakage. Whenever a wheel breaks, a careful inspection shall be made to make sure th at the hood has not been damaged, nor the flanges bent or sprung out of true or out of balance. The spindle and nuts shall also be carefully inspected. 11.3. Replacing hood. After mounting a new wheel, care should be taken to see th at the hood is properly replaced. 11.4. Starting new wheels. All new wheels shall be run at full operating; speed for at least one minute before applying work, during which time the operator shall stand a t one side. 11.5. Applying work. Work should not be forced against a cold wheel, but applied grad ually, giving the wheel an opportunity to warm and thereby minimize the chance of breakage. This applies to starting work in the morning in cold rooms, and to new wheels which have been stored in a cold place. 11.6. Test for balance. Wheels should be occasionally tested for balance, and rebalanced if necessary. 11.7. Truing. Wheels worn out of round shall be trued by a competent man. Wheels out of balance through wear, which can not be balanced by truing or dressing, shall be removed from the machine. 11.8. Wet grinding wheels. Wheels used in wet grinding should not be allowed to stand partly immersed in the water. The water-soaked portion may throw the wheel dangerously out of balance. All wet tool grinders which are not so designed as to provide a con stant supply of fresh water shall be thoroughly drained a t the end of each day's work and a fresh supply provided just before starting. 11.9. Side grinding. Grinding on the flat sides of straight wheels is often hazardous and should not be allowed on such operations when the sides of the wheel are appreciably worn thereby or when any considerable or sudden pressure is brought to bear against the sides. 11.10. Dresser guards. Wheel dressers, excepting the diamond type, shall be equipped with guards over the tops of the cutters to protect the operator from flying pieces of broken cutters or wheel particles. SAFETY CODE FOB ABRASIVE WHEELS 27 11.11. Grinding room. The space about the machine should be kept light, dry, and as free as possible from obstructions. 11.12. lubrication. Care should be exercised so that the spindle will not become suffi ciently heated to damage the wheel. 11.13. Check for wear. All arbors, adaptors, or other machine parts in which wheels fit, should be periodically inspected and maintained to size. (See rule 4.6.) INDEX Page Abrasive wheel, definition.............................. 4 Adjustment of work rest................................ 16 Adaptovs, definition....................................... 4 Adaptors, specifications-...............................18,19 Applying work, method of............................. 26 Balance and finish of flanges.......................... 17 Balance, testing wheels for.......................— 26 Bands, protection; definition of-.................... 5 Bands, protection; specifications for............. 16 Bearing boxes, requirements.......... ............... 27 Bench and floor stands, exposure allowed— 8 Blotters....... .................. ............................... 22,23 Breakages, wheel; inspection after................. 26 Bushings, general requirements..................... 22 Cast hood, definition...................................... 4 Cast hood, specifications. (See Hoods.) Castings, specifications for..... ........................10,11 Chucks, protection; definition of................... 5 Chucks, protection; specifications for............ 16 Collars, safety. (See Flanges, protection.) Compressible washers.................................... 22,23 Connecting members of hoods, specifications for................................................................. 15 12 Connection requirements for hoods............... Construction guide for hoods......................— 12 Control of speed adjustment-.........-....... — 24 Cracked wheels, inspection for_______ ___ 5,22 Cups, protection for_____ _________ ____ 16 Cylinders, protection for........................... —16 Cylindrical grinders, exposure allowed.......... 9 Definitions.................................... -................ 4,5 Degree of taper for protection flanges............ 20 Dimensions. (See article in question.) Direction of rotation....................................... 8 Direction of spindle thread............................ 8 Dresser guards...................................-........... 26 Dry grinding, dust exhaust provisions_____ 15 Dust exhaust provisions................................. 15 Exhaust, dust; provisions for......................... 15 Exposure adjustment..................................... 9 Exposure allowable, bench and floor stands.. 8 Exposure allowable, cylindrical grinders....... 9 Exposure allowable, surface grinders............. 9 Exposure allowable, swing frame and portable 9 Exposure allowable, top grinding.................. 9 Fabricated hood, definition............................ 4 Fabricated hood, specifications.. Hoods.) Fastenings and mounting for hoods.............. 8 Finish and balance of flanges......................... 17 Fit of flanges................................................... 17 Fit of wheel................................................. . 22 Flange facings............................ ....................22,23 Flanges, general requirements....................... 17 Flanges, protection; definition of................... 4,5 Flanges, protection; specifications for...........21,22 Flanges, straight; specifications for............... 17-20 Flanges, tapered; specifications for------------20-22 Floor and bench stands, exposure allowed.. . 8 Grinding room, general conditions................ 27 Handling and storage, precautions................ 5,6 Holes in flanges, size of...................................17-20 Holes in wheels, size of................................... 8 Hoods, protection; connecting members (specifications)............................................ 15 Hoods, protection; connection requirements. 12 Hoods, protection; construction guide—fabri cated noods.................................................. 12 Page Hoods, protection; definition____________ Hoods, protection; dimensions for peripheral and side members....................................... Hoods, protection; dust exhaust provision-__ Hoods, protection; inclosure requirements... Hoods, protection; exposure adjustment....... Hoods, protection; exposure for bench and floor stands.................................................. Hoods, protection; exposure for cylindrical grinders....................................................... Hoods, protection; exposure for surface grind ers................................................................ Hoods, protection; exposure for swing frame grinders........................................................ Hoods, protection; exposure for top grinding. Hoods, protection; fixed members................. Hoods, protection; general requirements....... Hoods, protection; material specifications... Hoods, protection; mounting and fastenings. Hoods, replacing after mounting Wheel......... Hub flanges, definition................................... 4 10 15 9 9 8 9 9 9 9 9 8 12 8 26 5 Inclosure requirements................................... Inspection of equipment after wheel break ages.............................................................. Inspection of wheels before mounting............ Inspection of wheels on receipt...................... Internal grinding, exception to protection re quirements................................................... 26 22 5,6 Lead-faced flanges........................................... Length of spindle thread............................... Lighting conditions in grinding room............ Limit stop for size of wheel............................ Lubrication of machine....................... .......... 23 8 27 8 27 9 5 Machine, bearing boxes.................................. 27 Machine, direction of spindle thread—......... 8 Machine, general requirements...................... 6-8 8 Machine, length of spindle thread................. Machine, limit stop........................................ 8 Machine, rigidity, supports, etc.................... 6 Machine, spindle size..................................... 6,7 Machine, wheel hole size................................ 8 Material for flanges, specifications................. 17 Material for hoods, specifications................... 12 Mounting of hoods......................................... 8 Mounting of wheels..................................... 22,23 Nut, spindle end; tightening of..................... 23 Opening in hoods, size of................................ 8,9 Peripheral member for hoods, dimensions__ 10 Portable and swing frame grinders, exposure allowed-...................................................... 9 Precision grinding, definition......................... 5 Protection bands. (See Bands.) Protection chucks. (See Chucks.) Protection devices, general requirements___ 5 Protection flanges. (See Flanges.) Protection hoods. (See Hoods.) Recess in flanges............................................. 17 Recommended and maximum speeds............ 23,24 Responsibility for care, etc............................ 26 Rests, work.....................................................15,16 Revolutions per minute and surface speeds. _ 25 Rigidity of supports....................................... 6 Ring flanges, definition.................................. 5 Ring wheels, sectional; protection for............ 16 Rotation, direction of..................................... 8 29 30 INDEX Page Safety collars. (See Flanges, protection.) Scope of code............................................ ...... 4 Sectional ring wheels, protection for.............. 16 Side grinding restriction................................. 26 Side members of hoods, dimensions............... 10 Size. (See article in question.) 4 Sleeves, definition.......................................... Sleeves, specifications.....................................19,20 Speed adjustment control............................... 24 Speed in revolutions per minute and surface feet per minute............................................ 25 Speed test....................................................... 24 Speeds, recommended and maximum........... 23,24 Spindle sizes................................................... 6,7 Spindle thread, direction of........................... 8 Spindle thread, length of............................... 8 Starting new wheels, test before.................... 26 Storage of wheels............................................ 5 Straight flanges, dimensions.......................... 17-20 Page Supports, rigidity of.............-....................... Surface grinders, exposure allowed................ Swing frame grinders, exposure allowed........ 6 9 9 20 Tapered flanges, degree of taper. - ................ Tapered flanges, dimensions..........................20-22 Tapered flanges, general requirements.......... 20 Test, balance................................................. 26 Test, speed.................................................... 24,26 Thread, spindle; direction of......................... 8 Thread, spindle; length of............................ 8 Tightening of nut. ....................................... 23 Top grinding, exposure allowed..................... 9 Truing of wheel............*.............................. 26 Washers, compressible...................................22,23 Wear, check for.............................................. 27 Wet grinding, provisions for........................ 26
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