BS 1916-1-2009 Limits and fits for engineering nPart 1 Guide to limits and tolerances《工程用极限与配合 第1部分 极限与公差指南》.pdf

1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI British StandardsWB9423_BSI_StandardColCov_noK_AW:BSI FRONT COVERS 5/9/08 12:55 Page 1Limits and fits for engineeringPart 1: Guide to limits and tolerancesBS 1916-1:2009BS 1916-1:2009 BRITISH STANDAR

2、DPublishing and copyright informationThe BSI copyright notice displayed in this document indicates when the document was last issued. BSI 2009ISBN 978 0 580 65212 7ICS 17.040.10The following BSI references relate to the work on this standard: Committee reference TDW/4 Draft for comment 09/30192598 D

3、CPublication historyFirst published March 1953Second (present) edition, September 2009Amendments issued since publicationDate Text affected BRITISH STANDARD BSI 2009 iBS 1916-1:2009ContentsForeword ii1 Scope 12 Normative references 13 Terms and definitions 14 Basis of conversion 25 Diameter steps 36

4、 Explanation of the system 37 Terminology 88 Selection of limits 89 Initial selection for normal use 810 Gauge limits 1011 Equivalent fits 1012 Limits for holes and shafts 10AnnexesAnnex A (informative) Rules for rounding-off tolerances 27Annex B (informative) Derivation of fundamental deviations 28

5、Annex C (informative) Special notes on tables of limits 30Bibliography 31List of figuresFigure 1 Diagram showing the disposition of limits and tolerances (Basic hole) 2Figure 2 Tolerance zones for holes arranged according to symbol 6Figure 3 Tolerance zones for shafts arranged according to symbol 7F

6、igure 4 Recommended selection of fits for general engineering requirements, basic hole system 9List of tablesTable 1 Fundamental tolerances of grades 1 to 16 5Table 2 Limits for holes (inch units) 11Table 3 Limits for shafts (inch units) 19Table A.1 Preferred series of tolerances 27Table B.1 Method

7、of determining the fundamental deviations for the various fits 28Summary of pagesThis document comprises a front cover, an inside front cover, pages i to ii, pages 1 to 32, an inside back cover and a back cover.BS 1916-1:2009ii BSI 2009BRITISH STANDARDForewordPublishing informationThis British Stand

8、ard is published by BSI and came into effect on 30 September 2009. It was prepared by Technical Committee TDW/4, Technical product realization. A list of organizations represented on this committee can be obtained on request to its secretary.SupersessionThis British Standard supersedes BS 1916-1:195

9、3, which is withdrawn.Relationship with other publicationsThis British Standard is published in three parts:Part 1 Guide to limits and tolerances;Part 2 Guide to the selection of fits in BS 1916-1;Part 3 Guide to tolerances, limits and fits for large diameters.The ISO 286 (BS EN 20286) series establ

10、ishes the ISO code-system for tolerances of linear sizes and is published in the following parts:ISO 286-1 (BS EN 20286-1), ISO system of limits and fits Part 1: Bases of tolerances, deviations and fits;ISO 286-2 (BS EN 20286-2), ISO system of limits and fits Part 2: Tables of standard tolerance gra

11、des and limit deviations for holes and shafts.The ISO 286 series covers the metric system of limits and fits; the BS 1916 series provides guidance and recommendations on the equivalent inch system (imperial).Information about this documentIn view of the time elapsed since its original publication in

12、 1953, this British Standard was reviewed in detail in 2009. It was decided that the technical provisions of the previous edition were still generally applicable, but the figures have been redrawn for ease of use, the wording of some guidance updated for clarity, and the opportunity was taken to upd

13、ate references to other standards.Use of this documentAs a guide, this part of BS 1916 takes the form of guidance and recommendations. It should not be quoted as if it were a specification or a code of practice and claims of compliance cannot be made to it.Contractual and legal considerationsThis pu

14、blication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application.Compliance with a British Standard cannot confer immunity from legal obligations.BRITISH STANDARD BSI 2009 1BS 1916-1:20091 ScopeThis part of BS 1916 gives guidance on

15、tolerances, limits and fits for engineering sizes up to 19.69 in. The recommendations apply particularly to fits between cylindrical parts, designated as “holes” and “shafts”, in which case the term “size” refers to the diameter of the mating parts. The data may also be applied in appropriate cases,

16、 by suitable selection of the grades of allowance and tolerances, to fits between other than cylindrical mating parts, in which case the “size” refers to a length, width or other dimension instead of to a diameter.The system described in this British Standard comprises suitable combinations of 16 gr

17、ades of tolerance and 21 types of fit for both hole and shaft, ranging from fits of extreme interference to those of extreme clearance. All but very exceptional engineering requirements are covered, from very coarse work to fine gauge manufacture.A selection of fits for general use is given in Figur

18、e 4, and further guidance on tolerances for shafts and holes for a wide range of fits is given in Part 2 of this British Standard, but it is intended that a particular industry or organization extracts and uses those limits which suit its own product. A unilateral hole basis system is recommended bu

19、t a full range of holes suitable for use on a shaft basis system, unilateral or bilateral, is also included in the tables.2 Normative referencesThe following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated

20、 references, the latest edition of the referenced document (including any amendments) applies.BS 969, Specification for limits and tolerances on plain limit gaugesBS 8888, Technical product specification Specification3 Terms and definitionsFor the purposes of this part of BS 1916, the following term

21、s and definitions apply.NOTE The basic terms used in this standard are illustrated in Figure 1.3.1 fundamental tolerancessixteen grades of tolerance for each size range on which the system is basedNOTE See Clause 6 and Table 1.3.2 deviationsalgebraic amounts by which the limits of size are greater (

22、+) or less () than the nominal sizeNOTE The deviations for the basic member of a mating pair are identical with the limits of tolerance for that member. The difference between the deviations for each member is equal to the tolerance for that member.BS 1916-1:20092 BSI 2009BRITISH STANDARDFigure 1 Di

23、agram showing the disposition of limits and tolerances (Basic hole)13 426111029548712 13 14LHKey1 Fundamental deviation2 Maximum interference (allowance)3 Tolerance4 Maximum clearance5 Minimum clearance (allowance)6 Minimum interference7 Nominal size8 Undersize hole9 Limits for size of shaft10 Limit

24、s for size of hole11 Oversize hole12 Clearance13 Transition14 Interference4 Basis of conversionIn order to obtain fit interchangeability between parts made to the metric system of limits and fits (see BS EN 20286) and to the equivalent inch system, the inch tolerance values have been obtained by dir

25、ect conversion of the metric tolerance values (see Annex A), 1 in = 25.4 mm.The tables were compiled as follows.a) The fundamental tolerances (described as IT1 to IT16) are obtained by converting and rounding-off the metric values.b) The fundamental deviations (“A” to “Z” for holes and “a” to “z” fo

26、r shafts) are obtained by converting and rounding-off the metric values.c) The final limits are obtained by adding the fundamental tolerances to, or subtracting them from, the fundamental deviations (see Clause 6).BRITISH STANDARD BSI 2009 3BS 1916-1:20095 Diameter stepsThe metric version (see BS EN

27、 20286) uses diameter increments or steps based partly on Preferred Numbers (see BS 2045) and partly (in the sizes below 180 mm) on existing metric practice. In the translation these steps have all been retained and converted to convenient inch equivalents, rounding being to the nearest hundredth of

28、 an inch in the upward direction. This ensures that preferred design sizes do not fall between the exact equivalent and the rounded value.The fine diameter steps are only used with some shafts and holes.6 Explanation of the system6.1 Fundamental tolerancesThe system provides for 16 grades of toleran

29、ces for each size range, designated IT1 to IT16 (see Table 1).NOTE The letters of the symbol “IT” stand for “International Tolerance” grade.These are called “fundamental tolerances” and are multiples of the fundamental tolerance unit “i” where:i (microns) = 0.45 D3+ 0.001 D (D in millimetres)ori (0.

30、001 in) = 0.052 D3+ 0.001 D (D in inches)where “D” is the geometric mean of the diameter steps involved.The tolerances of Grade IT6 are 10 i. The values IT7, IT8, etc. are 16 i, 25 i, etc., in a progression based on the five-series Preferred Numbers; IT12 is therefore ten times IT7, IT13 ten times I

31、T8, etc. Each tolerance grade is approximately 60% greater than its predecessor.The values of IT5 are 0.7 times the values of IT6; the values of IT1 are, however, arranged to suit gauge requirements, and the others, IT2 to IT4, in regular but arbitrary progression between IT1 and IT5.6.2 Fundamental

32、 deviationsThe tolerance determines the dimensional difference between two limits, but to establish the various fits, one of the limits should be determined as required by the design requirement, the other obtained by adding or subtracting the fundamental tolerance. The derivation of the various fun

33、damental deviations is given in Annex B.The positions of the tolerance zone boundaries nearest the zero line, i.e. fundamental deviations, are indicated by 21 letters, using capitals for holes and small letters for shafts, as follows.For holes: A B C D E F G H J K M N P R S T U V X Y ZFor shafts: a

34、b c d e f g h j k m n p r s t u v x y zBS 1916-1:20094 BSI 2009BRITISH STANDARD BRITISH STANDARD BSI 2009 5BS 1916-1:2009As shown in Figure 2 and Figure 3, the letters “A” to “H” and “k” to “z” inclusive apply to the tolerance zones above the reference line, the letters “A” and “z” corresponding to

35、the most distant. The letters “a” to “h” and “K” to “Z” inclusive apply to the tolerance zones below the reference line, the letters “a” and “Z” corresponding to the most distant.The tolerance zones “H” lie on the plus side only of the reference line, the tolerance zones “h” on the minus side only,

36、while the tolerance zones “J” and “j” lie on both sides of the reference line.Although a free association of the various shafts and holes is possible, it is strongly recommended that the unilateral hole basis system be used (“H” is the standard hole). In the hole basis system, shafts “a” to “h” are

37、provided for clearance fits and “j” to “z” for transition and interference fits.Holes for use on a unilateral shaft basis system may also be selected with “h” as the standard shaft. In the shaft basis system, holes “A” to “H” are provided for clearance fits and “J” to “Z” for transition and interfer

38、ence fits.BS1916-1:20094BSI2009BRITISHSTANDARDBRITISHSTANDARDBSI20095BS1916-1:2009Table 1 Fundamental tolerances of grades 1 to 16Nominal diameters(in)For gauges For fits Large tolerances (not for fits)Tolerance gradesIT1 IT2 IT3 IT4 IT5 IT6 IT7 IT8 IT9 IT10 IT11 IT12 IT13 IT14 IT15 IT16 0.04 G 0.12

39、 0.06 0.08 0.12 0.15 0.2 0.25 0.4 0.6 1.0 1.6 2.5 4.0 6.0 10.0 16.0 25.0 0.12 G 0.24 0.06 0.08 0.12 0.15 0.2 0.3 0.5 0.7 1.2 1.8 3.0 5.0 7.0 12.0 18.0 30.0 0.24 G 0.40 0.06 0.08 0.12 0.15 0.25 0.4 0.6 0.9 1.4 2.2 3.5 6.0 9.0 14.0 22.0 35.0 0.40 G 0.71 0.06 0.08 0.12 0.2 0.3 0.4 0.7 1.0 1.6 2.8 4.0 7

40、.0 10.0 16.0 28.0 40.0 0.71 G 1.19 0.06 0.08 0.16 0.25 0.4 0.5 0.8 1.2 2.0 3.5 5.0 8.0 12.0 20.0 35.0 50.0 1.19 G 1.97 0.08 0.12 0.16 0.3 0.4 0.6 1.0 1.6 2.5 4.0 6.0 10.0 16.0 25.0 40.0 60.0 1.97 G 3.15 0.08 0.12 0.2 0.3 0.5 0.7 1.2 1.8 3.0 4.5 7.0 12.0 18.0 30.0 45.0 70.0 3.15 G 4.73 0.12 0.16 0.24

41、 0.4 0.6 0.9 1.4 2.2 3.5 5.0 9.0 14.0 22.0 35.0 50.0 90.0 4.73 G 7.09 0.16 0.2 0.32 0.5 0.7 1.0 1.6 2.5 4.0 6.0 10.0 16.0 25.0 40.0 60.0 100.0 7.09 G 9.85 0.2 0.28 0.4 0.6 0.8 1.2 1.8 2.8 4.5 7.0 12.0 18.0 28.0 45.0 70.0 120.0 9.85 G 12.41 0.24 0.32 0.48 0.6 0.9 1.2 2.0 3.0 5.0 8.0 12.0 20.0 30.0 50

42、.0 80.0 120.0 12.41 G 15.75 0.28 0.36 0.5 0.7 1.0 1.4 2.2 3.5 6.0 9.0 14.0 22.0 35.0 60.0 90.0 140.0 15.75 G 19.69 0.32 0.4 0.6 0.8 1.0 1.6 2.5 4.0 6.0 10.0 16.0 25.0 40.0 60.0 100.0 160.0BB7BBBBB;BBBB8B BBBBBBBB7BBBBBBB;BBBB8 BB BB B B BBBBBBBBBBBBBBBBB7BBBBBBBBBBBBB BBBBBBBBBBS1916-1:20096BSI2009B

43、RITISHSTANDARDBRITISHSTANDARDBSI20097BS1916-1:2009Figure 2 Tolerance zones for holes arranged according to symbolA 9A 11B 8B 9B 11C 8C 9C 11D 8D 9D 10D 11E 7E 8E 9F 6F 7F 8F 9G 6G 7H 6H 7H 8H 9H 10H 11J 6J 7J 8J 9J 10J 11K 6K 7K 8M 6M 7M 8N 6N 7N 8N 9N 10N 11P 6P 7R 6R 7S 6S 7T 6T 7U 6U 7V 6V 7X 6X

44、7Y 7Z 7-50+5+10+151=0.001Not for fitsDiagram to scale for 1.19 in to 1.97 in.NOTE The holes V, X, Y and Z are not to be considered as definite recommendations, but for trials. The holes V and Y are to be avoided as much as possible.BS1916-1:20096BSI2009BRITISHSTANDARDBRITISHSTANDARDBSI20097BS1916-1:

45、2009Figure 3 Tolerance zones for shafts arranged according to symbola9a11b8b9b11c8c9c11d8d9d10e7e8e9f6f7f8g5g6h5h6h7h8h9h10h11d11k5k6k7k8k9k10k11m5m6m7y5y6j5j6j7j8j9j10j11z5z6n5n6n7p5p6p7r5r6r7s5s6s7t5t6t7u5u6u7v5v6v7x5x6x7-15-10-50+51=0.001Not for fitsDiagram to scale for 1.19 in to 1.97 in.NOTE Th

46、e shafts v, x, y and z are not to be considered as definite recommendations, but for trials. The shafts v and y are to be avoided as much as possible.BS 1916-1:20098 BSI 2009BRITISH STANDARD7 TerminologyA hole is described by the appropriate capital letter followed by a suffix number denoting the to

47、lerance grade, e.g. H7.A shaft is described by a small letter followed by a suffix number denoting the tolerance grade, e.g. p6.A fit is described by the hole symbol followed by that of a shaft, e.g. H7p6 or H7/p6.It is recommended that on production drawings, the actual limits for both hole and sha

48、ft should be explicitly stated by one of the methods in BS 8888, so that the parts to be measured by measuring instruments indicating actual size can be manufactured without reference to this British Standard. There are, however, certain circumstances for example, in general specifications, or on pr

49、eliminary design drawings in which it is convenient to be able to designate a particular type of fit by symbols only. In some workshops it is customary to use the symbolic notation on production drawings and for the identification of gauges, but where this is done, the symbols should be quoted in addition to the actual limits if any production requirements necessitate their use.8 Selection of limitsA particular industry or organization should extract from the tables those limits which best suit its own pr