1、USA STANDARD Preferred Limits and Fits for Cylindrical Parts USAS B4.1-1967 (R1974) Note For soft conversion of nominal dimensions and limits given in this standard, 1 inch = 25.4 mm. For explanation of conversion techniques see American National Standard 2210.1-1972, Metric Practice Guide. REAFFIRM
2、ED 1999 FOR CURRENT COMMllTEE PERSONNEL PLEASE SEE ASME MANUAL AS-11 sponmr The American Society of Mechanical Engineers THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS United Engineering Center 345 East 47th Street New York , N. Y. 10017 ANSI 84.1-1967 4 January 1972 ACCEPTANCE NOTICE The above Indust
3、ry Standardization Document was adopted on 4 January 1972 and is approved for use by the DoD. The indicated industry groups have furnished the clearances required by exist- ing regulations. Copies of the document are stocked by Do0 Single Stock Point, U.S. Naval Publi- cations and Forms Center, Phil
4、adelphia, Pennsylvania 19120, for issue to DoD activities only. Title of Document: Preferred Limits and Fits for Cylindrical Parts Date of Specific Issue Adopted: 18 September 1967 - Plus Errata Releasing Industry Group: The American Society of Mechanical Engineers Custodians: Army - MU Navy - SH Ai
5、r Force - 70 Military Coordinating Activity: Air Force - 70 Project No. MISC-0596 No part of this document may be reproduced in any form, in an electronic retrieval system or otherwise. without the prior written permission of the publisher. THE AMERICAN SOCIETY OF MECHASICAL ENGINEERS Copyrghr. a, 1
6、367. by Prlnred In U.S.A. Foreword T HIS standard represents the latest result of vork which began with the organization of Sec- tional Committee B4 in June 1920 under the name “Sectional Committee on the Standardiza- tion of Plain Limit Gages for General Engineering Work. ” This original committee
7、produced American Standard ASA B4a-1925, “Tolerances, Allowances and Gages for Metal Fits,” which was used in varying degree for many years. In December 1930, Sectional Committee 64 was reorganized and the name changed to the present form, “Sectional Committee on the Standardization of Allowances an
8、d Tolerances for Cylindrical Parts and Limit Gages.” The change in name indicated a significant shift to a more definite and somewhat more restricted mission for the committee. During the years of World War I1 an ASA War Committee formed in 1943 worked on the proj- ect but produced no completed resu
9、lts, and the activity was turned back to Sectional Committee B4. After the war the subject was discussed at the Canadian Conference on the Unification of Engineering Standards held in Ottawa in 1945, attended by delegates from Great Britain, Canada, and the United States, and again at another joint
10、meeting in New York later in the same year. These meetings are significant because since 1945 work in this project has been strongly in- fluenced by these and similar ABC conferences. Proper evaluation of the present standard will depend upon an appreciation of the important effects of progress towa
11、rds agreement on uni- fication of standards between the ABC countries. The result of the activities immediately following World War 11 was .4merican Standard “Limits and Fits for Engineerirg and Manufacturing (Part I), ASA B4.1-1947.” In the preface to that document it was stated that the ABC meetin
12、gs resulted in agreement on five basc principles, and since the first four of these principles, with certain minor and obvious variations, apply to this present standard, it is considered worth while to repeat them here. First, there must be a common language (definitions) through which analyses may
13、 be recorded and conveyed. Second, a table of preferred basic sizes helps in reducing the number of different diameters commonly used in a given size range. Third, preferred tolerances and allowances are a logical comple- ment to preferred sizes and should aid the designer in se!ecting standard tole
14、rances. Fourth, uniformity of method of applying tolerances is essential. Additional ABC conferences were held in New York in June 1952 and February 1953. Delega- tions from Sectional Committee B4 were active in these conferences, which resulted in a draft proposal for an ABC system of Limits and Fi
15、ts, published as ASA 84/30. The Sectional Com- mittee B4 delegates to these conferences voted to recommend approval of the ABC proposals as the basis for an American standard if and when such a standard were developed. Since the publication of this standard there has been additional discussions at A
16、BC con- ferences held in Ottawa in June 1960 and at Arden House, New York, in September 1962. There has been an expansion of definitions under ASA B1.7, and they are reflected in the revision. The revised proposal was submitted to the sponsor organization and to the USA Standards Institute (formerly
17、 American Standards Association) for final approval as a USA Standard. This approval was granted on August 3, 1966. This revision, however, was never published as it was noted that other rhanges. agreed to at the Arden House ABC Conference, had not been incorporated in the standard. A new revision w
18、as issued, and following approval by the USA Standards Committee 84, it was approved by the sponsor and on September 18, 1967 by the USA,Standards Instirute. USA STANDARD This USA Standard is one of nearly 3000 standards approved as American Standards by the American Standards Association. On August
19、 24, 1966, the ASA was reconstituted as the United States of America Standards Institute. Standards approved as American Standards are now designated USA Standards. There is no change in their.index identification or technical content. UDC 621.753.1.3 111 . USA Standards Committee B4, Standardizatio
20、n of Allowances and Tolerances for Cylindrical Parts and Limit Gages OFFICERS G. H. Stimson, Chairman COMMITTEE MEMBERS AMERICAN SOCIETY FOR QUALITY CONTROL R. J. Morris, International Harvester Co., Chicago, I11 AMERICAN SOCIETY OF MECHANICAL ENGINEERS, THE Z. R. Bliss, Brown University, Providence
21、, R. I. R. T. Woythal, Kearney 8 Trecker Corp., Milwaukee, Wisconsin AMERICAN SOCIETY OF TOOL AND MANUFACTURING ENGINEERS G. H. Stimson, Greenfield Tap and Die, Division of United-Greenfield Corp., Greenfield, Mass. ANTI-FRICTION BEARING MANUFACTURERS ASSOCIATION, INC. H. L. Potter, The Fafnir Beari
22、ng Co., New Britain, Conn. BUSINESS EQUIPMENT MANUFACTURERS ASSOCIATION A. E. Mall, International Business Machines Corp., Endicott, N. Y. METAL CUTTING TOOL INSTITUTE A. F. Miller, Jr., Wells Tool Co., Greenfield, Mass. NATIONAL ELECTRICAL MANUFACTURERS ASSOCIATION F. V. Kupchak, Westinghouse Elect
23、ric Corp., Pittsburgh, Pa. L. D. Price, Alternate, National Electrical Mfgrs. Association, New York, N. Y NATIONAL MACHINE TOOL BUILDERS ASSOCIATION F. S. Blackall, 111, The Taft-Peirce Mfg. Co., Woonsocket, R. I. SOCIETY OF AUTOMOTIVE ENGINEERS, INC. R. F. Holmes, General Motors Technical Center, W
24、arren, Michigan SPORTING ARMS AMMUNITIONS MANUFACTURERS ASSOCIATION J. F. Walsh, Olin Mathieson Chemical Co., New Haven, Conn. U. S. DEPT. OF THE ARMY C. B. Keane, Frankford Arsenal, Philadelphia, Pa. U. S. DEPT. OF COMMERCE I. H. Fullmer, National Bureau of Standards, Washington, D. C. U. S. DEPT.
25、OF THE NAVY Code 609.3C, Bureau of Ships, Navy Dept., Washington, D. C. J. C. Reid, Alternate, Bureau of Ships, Navy Dept., Washington, D. C. U. S. MACHINE, CAP, WOOD AND TAPPING SCREW BUREAUS H. G. Muenchinger, Holo-Krome Screw Corp., Hartford, Conn. INDIVIDUALMEMBERS W. S. Brown, Roanoke, Virginia
26、 H. W. Fahrlander, Sr., St. Petersburg, Fla. W. H. Gourlie, West Hartford, Conn. R. E. W. Harrison, Harrison Engineering Services, Inc., Washington, D. c. Ronald Jones, Westinghouse Electric Corp., Philadelphia, Pa. A. 0. Schmidt, The Pennsylvania State University, University Park, Pa. L. F. Spector
27、, Hitchcock Publishing Co., Wheaton, Ill. H. D. Stover, Timken Roller Bearing Co., Canton. Ohio iv USA Standard Preferred Limits and Fits for Cylindrical Parts 1. Scope and Application. 1.1 This standard presents definitions of terms applying to fits between plain (non-threaded) cylindrical parts an
28、d makes recommendations on preferred sizes, allowances, tolerances, and fits for use wherever they are applicable. The stand- ard through 20 in. diameter is in accord with the recommendations of American-British-Canadian Conferences. Experimental work is being carried on and when results are availab
29、le, agreement in the range above 20 in. will be sought. It repre- sents the combined thinking and experience of groups who have been interested in standards in this field, and it should have application for a wide range of products. The recommendations, therefore, are presented for guidance and for
30、use where they might serve to improve and simplify products, practices, and facilities. Many factors, such as length of engagement, bearing load, speed, lubrication, temperature, humidity, surface texture, and materials, must be taken into consideration in the selection of fits for a particular appl
31、ication, and modifications in these recommendations might be required to satisfy extreme conditions. Subsequent adjust- ments might also be desired as the result of ex- perience in a particular application to suit cri- tical functional requirements or to permit optimum manufacturing economy. Selecti
32、on of departure from these recommendations will depend upon consideration of the engineering and economic factors that might be involved. 2. Definitions 2.1 Terms relating to the size and fit of parts which are generally applicable to mechanical parts, are defined as follows: 2.2 Dimension. A dimens
33、ion is a geometrical characteristic such as diameter, length, angle, or center distance. The term “dimension” is also used for convenience to indicate the size or numerical value of a dimension as specified on the drawing. 2.3 Size. Size is a designation of magnitude. When a value is assigned to a d
34、imension it is re- ferred to hereinafter as the size of that dimension. NOTE: It is recognized that the words “dimension” and “size” are both used at times to convey the mean- ing of magnitude. 2.4 Nominal Size. The nominal size is the de- signation which is used for the purpose of general identific
35、ation. 2.5 Basic Size. The basic size is that size from which the limits of size are derived by the application of allowances and tolerances. 2.6 Reference Size. A reference size is a size without tolerance used only for information pur- poses and does not govern machining or inspec- tion operations
36、. 2.7 Design Size. The design size is the basic size with allowance applied, from which the limits of size are derived by the application of tolerances. If there is no allowance the design size is the same as the basic size. 2.8 Actual Size. An actual size is a measured size. 2.9 Limits of Size. The
37、 limits of size are the applicable maximum and minimum sizes. (See 2.14, Tolerance Limit) 2.10 Maximum Material Limit. A maximum ma- rerial limit is that limit of size that provides the maximum amount of material for the part. Nor- mally it is the maximum limit of size of an exter- nal dimension or
38、the minimum limit of size of an internal dimension. 2.11 Minimum Material Limit. A minimum ma- terial limit is that limit of size that provides the minimum amount of material for the part. Normal- ly it is the minimum limit of size of an external dimension or the maximum limit of size of an in- tern
39、al dimension. NOTE: An example of exceptions: an exterior corner radius where the maximum radiw is the minimum ma- material limit. terial limit and the minimum radius is the maximum 1 USA STANDARD 2.12 Allowance. An allowance is a prescribed difference between the maximum-material-limits of mating p
40、arts. It is the minimum clearance (pos- itive allowance) or maximum interference (nega- tive allowance) between such parts. (See 2.17 Fit.) 2.13 Tolerance. A tolerance is the totai permis- sible variation of a size. The tolerance is the difference between the limits of size. NOTE: The plural term “t
41、olerances” is sometimes used to denote the permissible variations from the specified or design size, when the tolerance is ex- pressed bilaterally. In this sense the term is identi- cal to “Tolerance limit.” 2.14 Toleraoce Limit. A tolerance limit is the variation, positive or negative, by which a s
42、ize is permitted to depart from the design size. (See 2.9, Limits of Size) 2.15 Unilateral Tolerance. A unilateral toler- ance is a tolerance in which variation is per- mitted only in one direction from the design size. 2.16 Bilateral Tolerance. A bilateral tolerance is a tolerance in which variatio
43、n is permitted in both directions from the design size. 2.17 Fit. Fit is the general term used to signify the range of tightness or looseness which may result from the application of a specific combina- tion of allowances and tolerances in the design of mating parts. 2.18 Actual Fit. The actual fit
44、between two mating parts is the relation existing between them with respect to the amount of clearance or interference that is present when they are as- sembled. NOTE: Fits are of three general types: clearance, transition, and interference. 2.19 Clearance Fit. A clearance fit is one having limits o
45、f size so prescribed that a clear- ance always results when mating parts are as- sembled. 2.20 Interference Fit. An interference fit is one having -limits of size so prescribed that an inter- ference always results when mating parts are assembled. 2.21 Transition Fit. A transition fit is one having
46、limits of size so prescribed that either a clearance or an interference may result when mating parts are assembled. 2.22 Unilateral Tolerance System. A design plan which uses only unilateral tolerances is known as a unilateral tolerance system. 2.23 Bilateral Tolerance System. A design plan which us
47、es only bilateral tolerances is known as a bilateral tolerance system. 2 2.24 Basic Hole System. A basic hole system is a system of fits in which the design size of the hole is the basic size and the allowance, if any, is applied to the shaft. 2.25 Basic Shaft System. A basic shaft system is a syste
48、m of fits in which the design size of the shaft is the basic size and the allowance, if any, is applied to the hole. 3. Preferred Basic Sizes In specifying fits, the basic size of mating parts shall be chosen from the following tables (one for fractional and one for decimal sizes) whenever possible.
49、 All dimensions are given in inches. 1/64 1/32 1/16 3/32 1/8 5/3 2 3/16 1/4 5/16 3/8 7/16 1/2 9/16 5/8 11/16 3/4 7/8 1 :/4 1 1/2 1 3/4 2 2 1/4 2 1/2 2 3/4 3 3 1/4 3 1/2 3 3/4 4 4 1/4 4 1/2 4 3/4 1 TABLE 1 Preferred Basic Sizes Fractional 0.015625 5 0.03125 5 1/11 0.0625 5 1/2 0.09375 5 3/4 0.1250 6 0.15625 6 1/2 0.1875 7 0.2 500 7 1/2 0.3 125 a 0.3750 8 1/2 0.4375 9 0.5000 9. 112 0.5625 10 0.6250 10 1/2 0.6875 11 0.7500 11 1/2 0.8750 12 1.0000 12 1/2 1.2500 13 1.5000 13 1/2 1.7500 14 2.2500 15 2.5000 15 1/2 2.7500 16 3.0000 16 1/2 3.2500 17 3.5000 17 1/2 3.7500 18 4.0000 18 1/2 4.2500 19 4
