ASME B18.25.3M-2008 pdf download.SQUARE AND RECTANGULAR KEYS AND KEYWAYS: WIDTH TOLERANCES AND DEVIATIONS GREATER THAN BASIC SIlE.
1.1 Scope 1.1.1 This Standard covers requirements for square and rectangular parallel keys and keyways intended for both alignment of shafts and hubs, and transmitting torque between shafts and hubs. 1.1.2 Keys covered by this Standard have a rela- tively loose width tolerance. All width tolerances are positive. Keys with minus width tolerances and a smaller tolerance range are covered by ASME B 18.25.1M. 1.1.3 The inclusion of dimensional data in this Standard is not intended to imply that all sizes described are production stock items. Consumers should consult with suppliers concerming lists of stock items. 1.2 Comparison With ISO R773-1969 and 2491-1974 This Standard has greater tolerances than ISO Stan- dards R773- 1969 and 2491-1974. Product manufactured to this Standard is not interchangeable dimensionally with product manufactured to the ISO standards nor is product manufactured to the ISO standards dimension- ally interchangeable with product manufacturcd to this Standard. ISO standards do not include hardened keys. 1.3 Dimensions Unless otherwise specified, all dimensions in this Standard are in millimeters.
1.4 Tolerances Many of the tolerances shown in Tables 1 and 2 are from ANSI B4.2 (ISO 286-1 and ISO 286-2). As a result, in addition to plus-minus tolerances which are common in the U.S, some are expressed as plus-plus deviations from the basic size. For further interpretation of these tolerances, refer to ANSI B4.2 or ISO 286.
1.5 Terminology For definitions of terms related to fasteners or compo- nent fasteners used in this Standard, refer to ANSI B18.12. 1.6 Referenced Standards ANSI B18.12, Glossary of Terms for Mechanical Fas- teners ASME B18.25.1M, Square and Rectangular Keys and Keyways ISO Standard R773-69, Rcctangular or Square Parallel Keys and Their Corresponding Keyways ISO Standard 2491-1974, Thin Parallel Keys and Their Corresponding Keyways (Dimensions in millimeters) ISO Standard 286-1-1988, ISO System of Limits and Fits一Bases of Tolerances, Deviations and Fits ISO Standard 286-2-1988, ISO System of Limits and Fits一Tables of Standard Tolerance Grades and Limit Deviations for Holes and Shafts Referenced ASME standards may be obtained from the American Society of Mechanical Engineers, 22 Law Drive, Box 2300, Faifield, New Jersey 07007-2300 Referenced ANSI and ISO standards may be obtained from the American National Standards Institute, 11 West 42nd Street, New York, NY
1.7 Designation Keys conforming to this Standard shall be designed by the following data, preferably in the sequence shown: (a) ASME document number, (b) product name, (c) nominal size (width (b) x height (h) x length), (d) style, . (e) hardness (if other than non-hardened) or option- ally by ASME B18.24.1, Part ldentification Number (PIN) Code System Standard for B18 Externally Threaded Products. EXAMPLES: (I) K253NAB003020302NNAAI (2) K253NBF010040302NNAAI