1、BS 969:2008Specification for limits and tolerances on plain limit gaugesICS 17.040.10NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBRITISH STANDARDIncorporating Corrigendum No.1Publishing and copyright informationThe BSI copyright notice displayed in this document indicates w
2、hen the document was last issued.The following BSI references relate to the work on this standard:Committee reference TDW/4Draft for comment 08/30177723DCPublication historyFirst published August 1941First revision, May 1953Second revision, May 1982Third revision, November 2008Amendments issued sinc
3、e publicationAmd. no.Date Text affectedBS 969:2008 BSI 2009ISBN978 0 580 687433C1 See foreword August 2009 iBS 969:2008ContentsForeword ii1 Scope 12 Terms and definitions 13 Gauge limits and tolerances 24 Hardness 25 Marking 26 Gauges in disagreement 3AnnexesAnnexA (informative) Examples oftheuse of
4、 Table 1 5Annex B (informative) Principles of inspection using plain limit gauges 6Annex C (informative) Values for gauges in imperial units 10Bibliography 12List of figuresFigure 1 Relationships of workpiece and gauge tolerance zones 4Figure A.1 Limits for hole 5Figure A.2 Limits for shaft 6Figure
5、B.1 Possible extreme errors of form allowed by the effects of the limits of workpiece size: holes 8Figure B.2 Possible extreme errors of form allowed by the effects of the limits of workpiece size: shafts 9List of tablesTable 1 Gauge size limits at 20 C for ranges of workpiece tolerance 3Table 2 Min
6、imum gauge tolerance appropriate totype and size ofgauge 4Table C.1 Gauge size limits at 20 C for ranges of workpiecetolerance in imperial units 10Table C.2 Minimum gauge tolerance appropriate to type and size of gauge (imperial units) 11Summary of pagesThis document comprises a front cover, an insi
7、defront cover, pagesiandii, pages 1 to 12, an inside back cover and a back cover. BSI 2009BS 969:2008iiForewordThis British Standard is published by BSI and came into effect on32008.ItwaspreparedbyTechnicalCommitteeTDW/4, Technical product realization.SupersessionInformation about this documentThis
8、British Standard has been fully revised to bring it up to date.Presentational conventionsThe provisions of this standard are presented in roman (i.e. upright) type. Its requirements are expressed in sentences in which the principal auxiliary verb is “shall”.Commentary, explanation and general inform
9、ative material is presented in notes in smaller italic type, and does not constitute anormative element.This publication 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 conferimmunity
10、from legal obligations.0NovemberThe start and finish of text introduced or altered by Corrigendum No. 1 is indicated in the text by tags PQ.Contractual and legal considerations BSI 2009BS 969:2008 supersedes BS :1982, which is withdrawn.969 1BS 969:20081ScopeThis British Standard specifies tolerance
11、s and limits for simple forms of limit gauges, such as cylindrical plain plug, ring and gap gauges, for which gauge limits have not been stipulated.It specifies gauge tolerances for workpiece tolerances in the rangebetween 0.009 mm and 3.200mm and how gauge limits are related to the workpiece limits
12、. It also specifies types of gauge according to size and minimum workpiece tolerance. NOTE Where a workpiece tolerance is outside the range 0.009 mm to 3.200 mm, or if it is not possible to conform to Table 2 regarding type of gauge, gauge tolerance and workpiece size, direct measurement should be u
13、sed.The gauge tolerances specified are such that the size of any workpieceaccepted by a gauge lies within the boundaries constituted by theworkpiece limits. Furthermore, the magnitude of the gauge tolerances is consequent upon the amount of the workpiece toleranceonly. A wear allowance is provided o
14、n all GO gauges, i.e. those that control the maximum material condition of the workpiece.2Terms and definitionsFor the purposes of this British Standardthe following termsanddefinitions apply.2.1 maximum material limit of sizedimension defining the maximum material condition of a feature at the maxi
15、mum limit of size for an external feature and at the minimum limit of size for an internal featureNOTE A shaft is an example of an external feature and ahole is an example of aninternal feature.2.2 least material limit of sizedimension defining the minimum limit of local size for an external feature
16、 or maximum limit of local size for an internal featureNOTE A shaft is an example of an external feature and a hole is anexample of aninternal feature.2.3 GO gaugegauge that controls the maximum material limit of size of the workpiece2.4 NOT GO gaugegauge that controlsthe least material limit of siz
17、e ofthe workpiece2.5 workpiece tolerancedifference between the high and low limits of size of the workpiece BSI 2009BS 969:200823Gauge limits and tolerances3.1 Gauge limitsWhere workpiece limits onlyare supplied to the gauges manufacturer (i.e. the purchaser doesnot state the required gauge limits),
18、 gauge limits for workpiece tolerances shall beas specified in Table 1(Annex A gives examples of the application of Table 1. Annex C gives the gauge size limits in imperial units).NOTE It will be seen that gauge tolerance increases with workpiece tolerance only. To appreciate this apparent disregard
19、 of workpiece size, it should be remembered that the size factor plays its proper part when the workpiece tolerance is fixed initially.3.2 Tolerances on gauge typesThe minimum tolerance on gauges shall be as specified in Table 2 (Annex C gives the minimum gaugetolerances in imperial units).NOTE 1In
20、most cases it is uneconomical to manufacture, and impractical to use, limit gauges with tolerances on sizes smaller than those specified in Table 2.NOTE 2 The GO gauges should be of full form and the NOT GO gaugesshould be designed to make contact at only the two ends of a diameter. The principle an
21、d reservations are described in Annex B.NOTE 3 Recommended gauge designs are given in BS 1044-1.4HardnessThe hardness of the gauging surface shall be not less than 700 HV (600 HRC).NOTE It is recommended that plain plug gauges of less than 6 mmnominal diameter should be suitably tempered on the reli
22、eved section toavoid breakage in use.5Marking5.1 Gauges shall be marked with:a) the limiting size of the workpiece which the gauge controls;b) GO or NOT GO, as appropriate.5.2 Gauges can also be marked with:a) the manufacturers name or trade mark;b) a serial number. BSI 2009 3BS 969:20086Gauges in d
23、isagreementIt is possible thatsimilar satisfactory gauges, using a different region ofthe permitted gauge tolerance, may respectively accept and rejectaworkpiece. Such cases are likelyto be rare and a dispute can be resolved by measuring the workpiecedirectly.Table 1 Gauge size limits at 20 C for ra
24、nges of workpiece tolerance (seeFigure 1)1234567Workpiece toleranceA) Tolerance, T,for GO and for NOT GO gaugesWear allowance, W, for GO gaugesonlyPlug type gaugesB) Ring or gap gauges C), D)GO NOT GO GO NOT GOmm mm mm mm mm mm mm0.009D)u 0.018 0.001 0.001 LHp H pp L + 0.018 u 0.032 0.002 0.001 p H
25、pp L + 0.032 u 0.058 0.003 0.002 LHp H pp L + 0.058 u 0.100 0.004 0.004 p H pp L + 0.100 u 0.180 0.006 0.007 LHp H pp L + 0.180 u 0.320 0.009 0.012 p H pp L + 0.320 u 0.580 0.014 0.025 LHp H pp L + 0.580 u 1.000 0.025 0.048 p H pp L + 1.000 u 1.800 0.040 0.080 LHp H pp L + 1.800 u 3.200 0.050 0.155
26、p H pp L +NOTE Gauge wearand wear allowance. Provision ismade for the wear of GO gauges by the introduction of awear allowance (W) between the tolerance zone for the gauge and the maximum material limit for the workpiece. Wear allowance is not applied to the NOT GO gauge.Gauge users have to watch fo
27、r the effect of wear upon sizes of their gauges. Regular examination and measurement of gauges in use is essential so that a gauge, particularly a GOgauge which has worn outsideits limit, is detected andwithdrawn from service to avoid accepting workpieces exceeding the maximum material limit.A) Diff
28、erence between high (H ) limit and low (L ) limit shaft or hole.B) Limits expressed withrespect to H minusL for the workpiece (hole). Errors of size and form of the gauge are tobecontained within these limits.C) Limits expressed withrespect to H minusL for the workpiece (shaft). Errors of size and f
29、ormof the gauge areto becontained within these limits.D) A workpiece with a tolerance lessthan 0.009 mm should be measured directly, or by means other than the gaugesdescribed in this standard.+0.0020.00100.001 0.0010.0020.0010+0.0030.00100.002 0.0010.0030.0020+0.0050.00200.003 0.0020.0050.0030+0.00
30、80.00400.004 0.0040.0080.0040+0.0130.00700.006 0.0070.0130.0060+0.0210.01200.009 0.0120.0210.0090+0.0390.02500.014 0.0250.0390.0140+0.0730.04800.025 0.0480.0730.0250+0.1200.08000.040 0.0800.1200.0400+0.2050.15500.050 0.1550.2050.0500 BSI 2009BS 969:20084Figure 1 Relationships of workpiece and gauge
31、tolerance zonesTable 2 Minimum gauge tolerance appropriate to type and size of gaugeGauge size TypeMinimum tolerance appropriate to the type and size of gaugeAbove Up to and includingmm mmCylindrical plug mm 25 0.00125 50 0.00250 100 0.003100 1500.006150 20 .009100 250 Cylindrically ended bar 0.0092
32、50 50 .016375750 Spherically ended rod andpin gauges0.0167501 000 0.030 13 Ring and gapgauges 0.00113 25 0.00225 50 0.00350 75 0.00675 175 0.009175 4000.016400 75 .030 BSI 2009PQHoleLow limitfor hole (L)High limitfor hole (H)High limitfor shaft (H)Tolerance forholeWorkpiecesTTPlug gaugesNot go gauge
33、Go gaugeDirection ofwear of gaugeDirection ofwear of gaugeWShaftLow limitfor shaft (L)Tolerance forshaftTTGap and ring gaugesGo gaugeNot go gaugeWGauges 5BS 969:2008Annex A (informative) Examples of the use of Table 1A.1 Example 1: Limits for holeThe limits forGO and NOT GO gauges for an internal di
34、ameter (hole) (see Figure A.1) are found as follows.The workpiece tolerance is 0.200 mm.a) From column 4 of Table 1, the limits for the GO gauge are:+ 0.021 mm+ 0.012 mmTherefore, the size of theGO gauge is:b) From column 5 of Table 1, the limits for the NOT GO gauge are:0 mmp 0.009 mm.H pA.2 Exampl
35、e 2: Limits for shaftThe limits forGO and NOT GO gaugesfor a shaft (see Figure A.2) are found as follows.The workpiece tolerance is 0.040 mm.a) From column 6 of Table 1, the limits for the GO gauge are:p 0.002 mmp 0.005 mmTherefore, the size of theGO gauge is:b) From column 7 of Table 1, the limits
36、for the NOT GO gauge are:+ 0.003 mm0Therefore, the size of theNOT GO gauge is:L +L + =0=Figure A.1 Limits for holeKey1 Workpiece175.2 mm (H )75 mm (L )H 0.00= BSI 2009P QTherefore, the size of theNOT GO gauge is:mmP Q02P Q0.009 mm75.200 mm75.191 mm75.021 mm75.012 mm0.021 mm0.012 mmmm.005 mm44.928 mm
37、44.925 mm44.893 mm44.890 mm0.003 mm0 mmP QBS 969:20086Annex B (informative) Principles of inspection using plain limit gaugesB.1 Limits The workpiece limits of size within the prescribed length of assembly are considered to be as follows.a) Holes. The diameter of a perfect cylinder just contacting t
38、he high points of the workpieceis to be not less than the workpiece lowerlimit. The maximum diameter at any positionin the hole does not exceed the workpiece upper limit.b) Shafts.The diameter of a perfect cylinder just circumscribing the shaft is to be not more than the workpiece upper limit. The m
39、inimum diameter at any position onthe shaft is to be notless than the workpiece lower limit.These considerations mean that if the workpiece is everywhere at its maximum material limit, it should be perfectly round and straight.Unless specific tolerances on circularity of section and straightness are
40、 specified, departures of the workpiece from cylindrical form can reach the diametral tolerance only if the workpiecesize is at the least material limit. Examples of extreme errors in form are shown in Figure B.1 and Figure B.2.B.2 Application of limit gauges to workpiecesNOTE The relationship of th
41、e limits for gauges to the workpiece limits is given in Figure 1.B.2.1 The maximum material limit of a workpiece, i.e. the upper limitfor a shaft or the lower limit for a hole, should be checked with a full form GO gauge thatshouldbe ofthe same length as the intended assembly of workpieces, shafts a
42、nd holes concerned. The workpiece has to pass into or over the gauge.B.2.2 The least material limit of a workpiece, i.e. the lower limit for a shaft or the upper limit for ahole, should be checked with a NOT GO gauge designed to contact the workpiece at two diametrically opposite points. The workpie
43、ceis not to pass into or over the gauge at anydiametral position around and along the workpiece length.Figure A.2 Limits for shaftKey1 Workpiece144.93 mm (H )44.89 mm (L ) BSI 2009 7BS 969:2008B.2.3 The system of checking described in B.2.1 and B.2.2 is knownas the Taylor Principle. For practical re
44、asons the following departures from the strictapplication ofthe Taylor Principle are recognized.a) Gauging at the maximum material limit1) The length of a GO cylindrical plug or ring gauge may be lessthan thelength of engagement of the mating workpieces if it is known that, with the manufacturing pr
45、ocess used, the error of straightnessof the hole or shaft is so small that it does not affect the character of fit of the assembled workpieces. This departure from the ideal facilitates the useof standard gauge blanks.2) A GO cylindrical plug gauge might be too heavy forgauginga large hole. It is pe
46、rmissible to use instead a segmental cylindrical bar or spherical gauge if it is known that with the manufacturing process used, the error of roundness or straightness of the hole is so small that it does not affect the character of fit of the assembled workpieces.3) A GO cylindrical ring gauge is o
47、ften inconvenient for gauging shafts and may be replaced by a gap gauge if it is known that, with the manufacturing process used, the errors of roundness (especially lobing) and of straightness of the shaft are so small that they do not affect the character of fit of the assembledworkpieces. The str
48、aightness of long shafts that have a small diameter should be checked separately.b) Gauging at the least material limit1) Point contacts are subject to rapid wear and in most cases may be replaced, where appropriate, by small plain cylindrical or spherical surfaces.2) For gauging very small holes, a
49、 two-point checking device is difficultto design and manufacture. NOT GO plug gauges offull cylindrical form might have to be used but the user has to be awarethat there is a possibility of accepting workpieces having a diameter outside the NOT GO limit.3) Non-rigid workpieces can be deformed to an oval by a two-point mechanical contact device operating under a finitecontact force. If it is not possible to reduce the contact force almost to zero, then it is necessary to use NOT GO ring or plug gauges of full cylindrical form.Thin-walle
