Fifth Reprint NOVEMBER 1996 ncorporting Amendments No.1 104) Is: 3455-1971 Indian Standard ( Reatfirmed 1996) GAUGING PRACTICE FOR PLAIN WORKPIECES (First Revision ) Loys down the gauging ction of ejaces wi dine is standard also gives the manufacturing tolerances and the permissible west 2. Inspection Gauging of Plain Workpiece: 2 Unless specified to the contrary, inspection by limit gauges is recognized as the acceptable method for dimensional conformity to tho specification of plain workpieces, To avoid any dispute requiring checking of the conformity of the gauges of the manufacturer, the following procedure is recommended in the use of gauges of the manufacturer and of the purchaser. 2.2 Inspection by the Manufacturer — Generally the inspection department that checks the workpieces made in the workshop may use the seme types of gauges as those used in the workshop. In ordor to Avoid differences between the results obtained by the workshop and inspection department it is recom. mended that the workshop uses new of only slightly worn gauges whilst the inspection department uses ‘gauges having sizes nearer the permissible wear limit. 2.8 Inspection by the Purchaser — There are three possible procedures for inspection on behalt of the purchaser by an inspector who does not belong to the manufacturing plant concerned: ®) the inspector may gauge the workpieces with the manufacturer's own gauges, providing he first checks the accuracy of these gauges; is own gauges, made in accordance with this standard, for inspecting Itis recommended that these gauges should have sizes near the wear limit in ‘order to avold differences betwoen the results obtained by the manufacturer and the inspector ©) the inspector may use his own inspection gauges for checking the workpieces. The dis- position of the tolerance zones for these gauges should be such as to ensure that the inspector does not reject workpieces the sizes of which are within the specified limits, 3. Reference Temperature \gth measurements shall be 20°C, This is also the temperature at which dimensions specified for workpieces and the inspection instruments cre defined and at which the Inspe ‘ion should normally be carried out. 3.2 If the workpiecss and the gauges have the same coefficient of linear expansion ( for example, stee! workpieces and steel gauges ), the checking temperature may deviate trom 20°C: without dettinient 10 the result, provided that the wemperatures of both gauges and workpieces are the sama, 3.8 If the workpieces and gauges have different coefficients of linear expansion ( for example, steol workpieces and carbide gauges or brass workpieces and gauges of steel or carbide }, the temperatures of both should be close to 20°C at the time of gauging. 4. Limits of Size for Gauging (Taylor Principle ) 4. In order to ensure, as far as is practicable, that the functional requirements of the limits of sizes as given in IS : 919-1963 " Recommendations for limits and fits for engineering ( revised ) ‘are attained, the Timits of size should be interpreted in the following way within the basic dimensions: 8) For holes, tho diameter of the largest perfect imaginary eylinder which can be inscribed wit the hole so that it just contacts the highest points of the surface, should not be a diameter smaller than the GO limit of size. In addition, the maximum diameter at eny position in the hole shall not exceed the NO GO limit of sizo. b) For shafts, the diameter of the smallest perfect imaginary cylinder which can be citcumscribed about the’ shaft so that it just contacts the highest points of the surface, should not be @ ameter iarger than the GO limit of size. In addition, the minimum diameter at any position on the shaft shall not be less than the NO GO limit of size. winter seit \ | © ror 199, os cac( "2 BUREAU OF INDIAN STANDARDS TQ 7EGO)? wc BHAVAN, © BAHADUR SHAH ZAFAR ARG aeok [NEW ELM ttooc2 ‘Adopted 20 Sey1S :3455- 1971 4.4.4 Tho abova interpretation means that if the size of the hole or shaft is every»here at its GO limit then the hole of shaft shall be perfectly round and straight. 4.2. Subject to the above requirements, departures from true roundness and straightness may reach the {ull value ofthe diametral tolerance specified. Typical extreme ators of form permited by this interpre- tation are illustrated in Fig. 1 and 2.. Such extreme errors are unlikely to aris Note — The above interpretation of the size limits results from the eo-caled Taylor principle, ealad altar the ame.ct to late W. Taylor mh frat lid it down i 1595. stem of ln gouges ind Noleas According to ths principle 8h ‘ath 2 GO spade othe speed 0 hint ofthe hol, having fang al east dshatls In aucition, the hole ia measured or gauged to check that fs rbxum ‘han the NO.GO mt 4.24 The shaft should assemble completely with a shaft and of a length at least equal to that of the length of engagement of the shaft and hole. Finally the shaft is measured or gauged to check that its minimum diameter is not smaller than the NO GO limit 4.2.2 In special cases the maximum errors of form permitted by the above interpretaticn may be too large to allow satistactory functioning of the assembled parts, arate tolerances should be given for the form, for example, separate tolerances on circularity or straightness. BEB pp her cower Nor GO wet | ~ 60 user FIG. 1 EXTREME ERRORS OF FORM OF HOLE ALLOWED BY THE RECOMMENDED INTERPRETATION OF THE LIMITS OF SIZE 5. Application of the Taylor Principle — Except for allowable deviations (see 8) st (of the Taylor principle leads to using: application 4) a plug gauge or a ring gauge having exactly the GO fimit diameter and a length equal to the workpiece length (or the engagement length of the fit to be made) for checking the GO limit of the workpiece; and 8) a gauge contacting the workpiaco surfaco only in swo dlamatrcally opposite points and having exactly the NO GO limit diameter for checking the NO GO limit. 5.4 The GO gauge should perfectly assemble with the workpiece to be inspected anti the NO GO. ‘gauge should not be able to pass aver or in the workpiece in any consecutive position in the various diametiical directions on the workpiece length. . (In order that the GO and NO GQ limits should not be ‘espassed, manufacturing and wear tolerances should be taken within these limits. ) Allowable Deviation from the Taylor Principle — As the application of the Taylor principle is not always strictly compulsory or comes up against difficulties in conveniently using gauges, ceriain deviations may be allowed (see 7.9).of the ‘nally fimit, ye too ould ation ‘al to > the aving » GO ot be not 8A Atthe a) ») ° 6.2 At the a) >) ° 668 Some thin-walled workpioces may be cut of ound (de to interna stssee oF hes retment $2 Sree Se wate wemnees mat be Sn ‘tae tow veiniosns ef Be oe eee ts: 3455-1971 sneuuscneD erie 2 EXTREME ERRORS OF FORM OF SHAFT ALLOWED BY THE RECOMMENDED INTERPRETATION OF THE LIMITS OF SIZE Fi {GO limit a full form gauge is not always necessary or used. For instance “Te length of # GO evtindseal plva oF rng gauge may be less than the length of engagement Tea Go ein! due 0m a a ae nt eat of the mating workpieces ie Shaft eso smal that doesnot affect the charactor of the anor of suaighiness ofthe Boles" Sfeviation from the Kea! faciates the se of standard gouge blanks. For gauging «lage hote «GO cylincical plug gauge may be too heavy for convenient use, ted‘ 8 pormlsbie te uso’a. segmental cylindrical ber or spherical gauge lit is known of and It is pemissible to use =, eeng process used tho error of rouremees of the hgle ws Sy ‘small that it does not affect the character of fit of the assembled workpieces. ‘AGO cylindrical ring gauge is often inconvenient for gauging shafts and may be replaced by 2 ep gauge If it fe known or assumed that with the manufacturing process used the errors of Tourdnese ( ospecially lobing ) and straightness of the shaft are so small that they do not SHlect tho character of fit of the assembled workpieces. The straightness of long shafts, Which have a small diamoter, should be checked separately. NO GO limit a two-point checking device is not always necessary or used. For instance: Point contacts are subject to rapid wear, and in most casés may be replaced where appro- priate by small plane, cylindrical of spherical surfaces. pe For gauging very small holes a two-point checking device is difficult to design and manu- faense. NO GO plug. gauges of full cylindseal form have to be used but the user must bo “hat there is'2 poseibinty of accepting workpieces having diameters outside the NO GO Non-rigid workpieces may be deformed to an oval by a two-point mechanical contact dovice Sparatig under a finite contact force. If ls not possible to reduce the contect force no ‘almost zero, for example, by using @ direct jet pneumatic device, then it is necessary to use NO ‘GO ting oF plug gauges of full cylindrical form. aaa ee Oat Be ranaireaand Thesotore NO GO gauges of ful cyindeal town hove eee eek Fa a ee ranea eater irt dhe lati cafonmation who elruladiy Cur Gate sat ono bor compress the wall of the workpiece. 31S :3455-1971 ‘A Lastly, itis not possible to make the gauges exactly to the appropriate workpioce limit; they require 6 be made to specified tolerances. 7. Limit Gauges 0 Limit gauges are used to inspect the workpieces. For gauging internal diameters, they are of the following types: a) Full form cylindrical plug gauge, b) Full form spherical plug or disk gauge, ) Segmental cylindrical bar gauge, d) Segmental spherical plug gauge, ‘©) Segmental cylindrical bar gauge with reduced measuring faces, and 4) Rod gauge with spherical ends, 7.01 For gauging external diameters, they are of the following types: ) Full form cylindrical ring gauge, and b) Gap gauge. 7.0.2 To inspect or adjust limit gauges, the following gauges may be'used: b) Block gauges are standards of longth having parallel lar {or calibrating gauges of indicating measuring instruments, Ad surfaces which are used 7A.A full form cylindrical plug gauge ( Fig. 3A.) has a gauging surface in the form of an external Jilinder.. The method of attaching the gauge to tho handle should not affect the size and foun of the ‘gauge by producing an undesirable stress. AAA small circurnferential groove near the leading end of the gauge and a slight reduction in dia- meter of the remaining short cylindrical surface at the and are recommended to serve 45 a pilot to faci the insertion of the gauge into the workpiace hole, 7.2 A full form spherical plug or disk gauge (Fig. 3B) has 9 gauging surface in the form of a sphore from which two equal segments are cUt off by planes normal ta the axis of tho handle 1a A segmental lind! bar gouge (F.C) has a gauging suraca In the form of an. exiema Sylinder from which two axial segments are either received [Fig. 3C (i) ] or removed [Fi il This gauge may have reduced measuring faces ( Fig. 3E ). sd [Fig. 3C (ii) |. 7.4 A segmental spherical plug gauge ( Fig. 3D) is similar to Fig. 3B but has two equal segments cutoff by planes porala 0 the axis of th hance in addition to tho segments cut off by planes nora to the axis of the handle, 1.6 A rod gauge with spherical ends (Fig. 3F ) has sph sphere. ical end surfaces which form part of one ingle tions of use. ~1513455 - 1971 . 2uge (Fig, 4B) has for Its working size flat and paral Ty, AetaN bas ae a and one oyinaioa! surtac, or two eyindoal surfaces the aaes of thaas Shlingricl euvaces being parallel tothe axis of the sheit being checked. The GO and NO GO geps ayo en the same side'of the gap gauge. The gep gauge may be fied or adjustable. gauging surfaces, or alternatively 3 A ra rom crunoncat rive woe @ (}- us rome smencas rus on ¢ samara cnaonca, ott cane Oh to © O- sera erence «O- seca F (AD neo owvoe wna smencas 2105 FIG. 9 RECOMMENDED TYPES OF GAUGES FOR HOLES AND THEIR CORRESPONDING SYMBOLS FOR FIG. § 4 © cunt Form cyunoricat © D car cause RING GAUGE FIG, 4 RECOMMENDED TYPES OF GAUGES FOR SHAFTS AND THEIR CORRESPONDING SYMBOLS FOR FIG. 61S 33455-1971 19 The various types of gauges explained above av illusuoted in Fig. 3 and 4. The recommended types Ppoauges forthe aifferoat ranges, of ominal size of the workplaces are shown In Fig. 8 and 6. The Role te the symbols Used in Fig, Band 6 ro given in Fig. 3 end 4 |workriece| causes |(ercmemee § 10 “to a) a Go wow co ees eis inet g 2 -—O-— i 7 E,-_& So = o- ve 02 = : Eee (SU : VR wo 0 oo : : — 2 § fporool | -_C}—--___ -§ ———-F- — FIG. 5 TYPES OF GAUGES USED TO CHECK HOLES, IN ORDER OF PREFERENCE ; a | a ge f eo 4 as i 2 SS ef] 6s [nen £ porcol 6 |} —__ FIG. § TYPES OF GAUGES USED TO CHECK SHAFTS, IN ORDER OF PREFERENCE 8. Inspection of Gauge Sizes 8.1 Reference Gauges—The gauge diameter should be measured between a plane and a spheri- cally-ended anvil having @ minimum radius of 10 mm. The value obtained should be corrected for deformation of the surfaces in contact caused by the measuring force, that is, the diameter of the gauge is the diameter when the measuring force is zero. The diameter should be measured in at least four positions selected to reveal form evar. 8.1.1 All the measured diameters of the gauge should be on or betwean the specified limits of size, ‘and the range, that is, the difference between the maximum and minimum values, should not exceed the form tolerance of the gauge (see 10.2.3). If the presence of lobing is suspected then it may be checked by @ three-point measurement or by 8 roundness measurement.1S 23455-1971 8.2 Spherical Plug, Disk and Red Gauges — Tho diameter of the spherical part of the gauge should bo measured between two parallel planes; these planes need only have a small area, for example, the diameter of the plane-ended surface of the anvil of a measuring Instrument may only be 6 mm. 8.2.4 The value obtained should be corrected for deformation of the surfaces in contact caused by the measuring force, that is, diameter of the gauge is the diameter when the measuring forca is zero. 8.2.2 The diameter should be measured in at least four positions, selected to reveal form errors. Al ‘tho measured diameters of the gauge should be on or between the specified limits of size, and the range, that is, the difference batween the maximum and minimum values, should not exceed the form tolerance ‘of the gauge (see 10.2.3). If the presence of lobing is suspected then it may be checked by a thres- point measurement or by @ roundness measurement. _ 88 Cylindrical Ring Gauges— The diameter is measured by means of two spherically-ended anvils positioned in a plane normal to the axis of the ring gauge. When moving the measuring instrument in {his plane the greatest distance epart of the two anvils determines tha diameter. The velue obtained should be corrected for deformation of the surfaces in contact caused by the measuring force, that is, the diameter of the gauge Is the diameter when the measuring force is zero. 8.3.1 The diameter should be messured in atleast four positions, selected to reveal form errors. All the measured diameters of the gauge should be on or between the specified limits of size, that is, the difference between the maximum and minimum velues, should not exceed ti ne of the gauge (see 10.2.3). If the presenca of lobing is suspected then it may be checked by ‘three-point measurement or by @ roundness measurement. 8.4 Gap Gauges 8.4.1. The actual size of a gap is defined as the perpendicular distance between the gauging surfaces, ‘when no force is exerted on the gauge. ‘The working size of a gap gauge is defined as the diameter of-a reference disk over-which the e just passes Ina vertical direction under the working load marked on it,-of, if this is not ‘under its own weight, Beforehand, the disk should be greased with a thin film of petroleum jelly end then carefully wipgd but not rubbed. The gauging surfaces of the gap gauge should be cleaned. The gap gauge should slide over the disk efter having been brought carefully to rest in Contact with the disk and then released: Inertia forces are 60 avoided. 3 For heavier gap gauges it is recommended that the working load should be less than the weight of the gauge, so that the working size may be determined more accurately. . The positions of the places, ‘where the forces counterbalancing part of the weight of the gauge are to be applied ( see Fig. 7) should ‘be matkad on gauges of nominel sizes above 100 mm. ke to FIG. 7 LOCATION OF POINTS WHERE FORCES COUNTERBALANCING PART OF WEIGHT OF GAUGE SHOULD BE APPLIED ‘of the reference disk to the workpiece, : ee 8.4.5 In practice a reference disk may be used directly to isk and the gap gauge ere supplied together and tha gap gau ‘cases the following two alternative procedures are recommende! @ gap gauge in the caso where the 38 been adjusted to the disk. In other 8) Tho successive toads under which the gap gouge will pass over two reference disks ditferantlometer ere detormined under ‘tho conditions epecttod. inthe deni a aie ‘working size. Tho differenco in those. two loads is taken as a besls for ealculsting tre ‘working size of the gap gaugo t its working loa 71s 23455-1971 b) A reference disk is teken with @ diameter smaller® than the smallest pormissible size of tho ‘gap gauge. Gauge blocks are wrung successively on the gauging surfaces of the gap Seuge, if possible equally distributed so that in one case the sum of the diameter of the feterence disk and the gauge blocks is equal to the lowest permissible working size and in the other case to the highest permissible working size of the gap gauget. In the fist case the gap gauge should pess over the reference disk, and in the second ‘case it should not pass over the reference disk, under the conditions specified in the definition of the working size, Doubtful cases are decided according to method ( b) above. 8.4.6 When the gap gauge is used in a horizontal position, with the axis of the workpiece vertical, ite working size is defined as the largest siza of a raference disk or gauge block combination over which it an just be moved by hand without excessive force. 1 The difference between the working size and the actual size of @ gap gauge is equal to the amount by which the gauge is deformed by the force applied when determining the working size. The dasign of the gap gauge should be as rigid as possible in relation to the weight of the gauge 80 as to keep this difference in size to a minimum. 9, Method of Use of Gauges — The following recommendations relate to the general use of the ‘gauges in the workshop as well as in inspection, 9.4 Gauges for Holes GO Gauge — A GO gauge should assemble completely with the hole when applied by hand without using excessive force, and tha total length of the hole should be checked. When gauging ‘non-rigid workpieces, such as thin-walled parts, the application of too great force will enlarge the diameter of the hole, A GO segmental gauge should be applied to the hole in at least two axial planes uniformly placed around the circumference. NO GO Gauge — Acylindrical NO GO plug gauge should not enter the hole when applied by hand without using excessive force. The hole should be checked from both ends, if possible, A.NO GO gauge with spherical measuring surfaces is entered into the hole by tilting it. When itis erected in the hole, contacting the hole on a diameter, it should not be possible to pass it through the hole by hand without using excessive force. This test should be performed at not less than four positions around and along the cylindrical surface of the hole, 9.2 Gauges for Shafts GO Gauge — Tho GO gap gauge should pasa over a shaft, the axis of which is horizontal, under its own weight or the force marked on the Gauge, under the conditions specified in 8.4 ‘The GO gap gauge should pass over a shaft, the axis of which is vertical, when applied by hand without using excessive force. It is recommended that the corresponding reference disk should be used to assess the measuring force. The above test should be applied at not less than four positions around and long the shaft. ‘A cylindrical GO ring gauge should pass over the complete length of the shaft when applied by hhand without using excessive force. NO GO Gauge—The NO GO gauge should not pass over a shaft, the axis of which is hotizonal, under its own weight or the force marked on the gauge, Under the onto Specified The NO GO gap gauge should not pass over a shaft the axis of which is vertical, when applied by hand without using excessive force. The above test should be applied at not less than four positions around and along the shaft. “For gap gauges up to 100 mum it i adviccble to make the dlameter of the disk 5 mm smi and for gup gauges ovar 100 mm, 10 mm smaller than the nominal sie. ‘Relecence disks made to the lowest and highest permissible sizes may also be used. lor than the nominal size, 8ts: 3455-1971 10, Manufacturing Tolerances and Permissible Wear of Gauges 10.1. Symbols — The following symbols are used in this standard: D_=nominal diameter of workpiece in millimetres: H H, = tolerance on spherical gauges: tolerance on eylindrical plug or cylindrical bar gauges; H, = tolerance on gauges for shatts; H, = tolerance on reference disks for gap gauges: y= margin, outside the GO workpiece limit, of the wear it of gauges for holes; = margin, outside the GO workpiece limit, of the wear limit of gauges for shafts; 2 = distance between centre of tolerance zone of new GO gauges for holes and GO workpiece ‘iri 2, = distance between centre of tolerance zone of new GO gauges for shafts and GO work- piece limit: 4 = safety zone provided for compensating measuring uncertainties of gauges for holes of ‘nominal diameter over 160 mm; 4, = safety 20ne provided for compensating measuring uncertainties of gauges for shafts of nominal diameter over 180 mm; and ¥ end y'; ~ difference in absolute value between y and « or y, and 2. 10,2 Limit Gauges 10.2.1 Positions of tolerence zones and wear limits in relation to workpiece limits ( shown diagram- matically in Fig. 9). NO GO limit of workpieces — The tolerance zone of new NO GO gauges for nominal sizes up to and including 180 mm is eymmatrical to the NO GO limit. For sizes above 180 mm the tolerance zone fe eymmettical toa line lying inside the woikpiece tolerance zone at Ince « oF 4 from the NO GO limit 6O limit of workgieces ~ 1) the tolerance zone of 2 new GO gauge is moved inside the workpiece tolerance by an amount Z or 21; ) the GO gauge is allowed to wear outside the GO limit of the workpiece by an amount y or yy when this val A reasonable life for GO gauges Is provided in two ways: cases, the ‘of the GO ly outside the GO limit of the workpiece (or to «and =, within ‘amount of the safet ‘gauges Is limited to y’ andy’ ret this limit ify and y" are equal to zero) ‘The values of the y or y, margin have been taken as small as possible in order to reduce to a minimum the risk that warkpis¢es with sizes outside the prescribed GO limit be accepted. This margin is therefore provided only in the case of smaller tolerances on workpieces, from IT6 to IT, the deletion fof this margin being possibly contemplated in the future (in connection with the development of low Cost low wear gauges). a In the range of sizes above 180 mm nominal diameter the workpiece tolerance has baen reduced, ‘at the GO (with y ory, margin) and NO GO limits, by the amount of the safety zones a and a,. Manu: facturers rohasers should’ not forget that due to errors of measurement the sizes of work. ig of the gauges by the amount of the safety zones « and 2, and that the n by y and y,, may be reached. extreme workpiece limits, gi 40.2.2 Tolerances on size of working gauges — The tolerances on size of working gauges are based on the fundamental tolerances of grades IT1 to IT7 and are shown in Table 1. Values of a, y, 2, etc, for the gauges are shown in Table 2. Gauge size for component tolerance *T not included in Table 2 shall be calculated by using the data for the next higher values of "Tin tl same range.15 13455. 2971 2 Tolerances on form of working gauges — The tolerances on form of working gauges are besed ont 1 fundamental ole inces of grades ITO to IT5.and ere shown in Table 1. 10.3 Reference Disks for Gap Gauges 10.3.4 Positions of tolerance zones with respect fo the workpiece limits ( shown diagrammatically in Fig. 8). 4, NO GO limit of workpiece — For nominal sizes up to and including 180 mm the tolerence zone of the raference disk is symmetrical to the NO GO limit. For sizes above 180 mm the tolerance zone is ‘Symmetrical to line lying inside the workpiece tolerance zone at distance « from the NO GO limit GO limit of workpiece —The tolerance zone of the reference disk for @ new gap gauge is ‘symmetrical to the 2, value. ‘The tolerance zone of the reference disk for checking wear is located in the following mann a) Workpieces of nominal sizes up to and including 180 mm —For tolerance grades 1T6 to ITB the tolerence zone of the reference disk is symmetrical to the y, value. For tolerence grades 179 0 1T16, y, is zero and nce disk is symmetrical to the GO limit of tho workpiece. b) Workpieces of nominal sizes above 180 mm —For tolerance grades IT6 to ITB the tolerance zone of the reference disk is symmetrical to the y’, value (y', =, — a), For tolerance: ‘Grades 1T9 to 1T16 y, Is zero and hence the tolerance zone of the feference disk is symmetrical to the value inside itie GO limit of the workpiece, 10.3.2 Tolerances on size of reference disks — The tolerances on size of the reference disks are based ‘on the fundamental tolerances of grades IT1 to IT3 and are shown in Table 1. Values of a, 4s 21 etc, for the reference disks are given in Table 3. Gauge size for component tolerance * T ', not included In Table 3 shall be calculated by using the data for the next higher values of 'T * in the sama range, 10.3.8 Tolerances on form of reference disks —- The tolerances on form of the reference disks are based on the fundamental tolerences of grades IT1 to IT2 and are shown in Table 1. 10.3.4 Relation between tolerances of gap gauges and their reference disks — The relation between the tolerances H; of the gap gauge and the tolerance of its reference disk H, Is as follows: H" determines the limits of size of the working size ( see clause 8.4) of a gap gauge. The difference between the limits of size given by Hi for the gap gauge and by H, for the reference disk represents a safety zone on both sides of H, to compensate for errors of measurement, in the same way as o and a; do for workpi F 180 mm. Hy and H- are, therefore, symmetci- cal ( see Fig. 8). Therefore, if according to the definition of working size, gap gauges lle outside the zone H? but within the zone H', they are still to be regarded as correct. tT Me Hy = manufacturing tolerance of the gep-geuge Hy = manufacturing foleranee ofthe reeronce disk FIG. 8 RELATION BETWEEN MANUFACTURING TOLERANCES OF GAP GAUGES AND OF REFERENCE GAUGES 101S 23455-1971 404 Reference Ring and Plug Gauges for Setting Measuring Instruments— The gauges should be made to tolerances on size and form equal to those for roference disks, The tolerance on size is disposed bilaterally with respect to the appropriate test limit of the workplace. The size of each gauge should be measured across a diameter halfway through the gauge, and the axial plane in which this diameter ‘occurs and the measured size of the gauge should id face of « 11, Formulae for Calculation of Gauge Dimensions 44.4, From the position of the tolerance zones and wear limits in relation to. workpiece limits illustrated in Fig. 9, the formulae for calculation of gauge limits can be computed and these are given below. In ‘ormulae, in addition to the symbols given in 10.4, the following are used: G= higher limit for workpiece, and K = lower limit for workpiec FORMULAE FOR GAUGE DIMENSIONS | Size Above 189 mm Tot oH 2 i || z | poe wot Kee) Hot Outside m Provides z Provides | | j | : | “snot nt be wed when sphere 14.2 Sample Calculation — Iilustrative examples for the calculation of gauge limits are given below: Required Gauge Size for 25C9 Plug Gauge The component tlarences wil bo + 0 ns ances willbe + 0482 according to 1S: 919-1062 Corresponding work limits will be G = 26°00 + 0-162 = 26-162 mm K = 26:000 + 0-110 = 25:110 mm "US 3455 - 1971 Baten) eae pore hater BEE oa Sites wom, sae | oH eames | oh ? i emehass| cd PT fe iy ie HI = ae os ee FIG, 9 TOLERANCE ZONES OF LIMIT GAUGES AND REFERENCE DISKS For plug gauges size can be calculated es under: =~ ‘NO GO si se H/2 = 26162 +: 0-002 mm *G0 size now = (K +2) + H/2 = ( 25:110 + 0:09) + 0:002 = 26419 + 0-002 mm G0 size wear limit = K—y = 25°110~ 0 = 25110 mm Required Gauge Size for Snap Gauge 270 +0 : — 005 “The component tolerance will bet G =270:000 mm K = 270 — 0°08 = 269:950 mm _ Snap gauge size can be calculated as un: a 7 460 size wearlimit = G+ y,—s1= 270°000 +0:007—o-0008 | = 270003 mm } $60 slzonew = = (G—%) EH, = (270'000~ 0-008) +0008 = 269'992 + 0°06 mm | JNO GO so == = (K+ aj) EH, = (26995040004) £0008 = © 269'954 + 0°08 mm \ “For actual ale of plug gauges tor Ate for 4 to $00 mm nominal size4, refer IS: ‘Gauge and manutacturingtlerance for plain gauges fo ialde mensuremente Yor 190 fi nse aomive ite up 49 fits from 1 0 nap gauges and {or outside met rid manufacturing te up te 200 mim. 1S : 3455-1971 ments 12. General Regt 12.1 No recommendations are given in this standard for datails of the design of gauges. The technical ‘supply conditions shall conform to IS : 7018-1973 ' Technical supply conditions for gauges . ‘The marking and designation of the Gauges shall also conform =. to the above Indian Standard. E TABLE | MANUFACTURING TOLERANCES FOR GAUGES i I — _ - 1 ie] Ame |) tee me [ome Tom [ew [Te | ae [Size Form | Size | Form) Size Form Size |Form| Size | Form| Size | Form cm | [eh | | 5 GY aS AY |S FP | GS | eH | f “T - ~| T — i loeearcn tr or lier) foe tell fetle (eae) af a) eel eee Mindrical Plug Gauge: | | i | | ees hlrrhLc 7 seats |] ola ale Tolerance -|-j-]- 2 1 1 Ja et | i Pete cr elt ef | | ai | sie, Bets. a | spafafals s|o] | Gauges 1 i { 7 Tolerance Grade tor cy-| — | —|—|—| aj 2! i Vinten Ring Gouges I eo elle i -|- | -|-|2 | Ce eee es) ee le -foprfopepebep aber afep el ey al | i | ity i7t ee come) t [| dial | el ed ol «| el ofl al etc | ee eee ale = ol aa \ i | pth \ | \ LEyon *Up to 6 mm diameter only. = icaeae - | 13a e- phy Gar4 1S: 3455-1971 TABLE 2 GAUGE TOLERANCES AND THEIR LOCATION FOR GAUGES FOR INSIDE MEASUREMENTS (HOLES) (Clause 10.22) (omy [ Nominaisie] | Work Tolerance Grades as per 150 5 loymbatd owe lee. 6} 7] ea] | wo] {2 | 13 | | os | 16 i Fr eC a ‘ + ‘ + oe 3 ¥ 2 2 o- ° 2 z [+ ma ze ze T 18 | 30 [ <6 | 75 J ye0_[_300 |" 400 | 750. « (= va ae 7 3 ¥ 2 o o o o z 7 7m T 22 36 [50 ‘580 | 300 a a " 6 | 10 [we mo a i fl ; 7 T 70 [380 [270 T 430 | 700 T1100 + t + c to| 18 a i oi T 33_ [sz T #4 [190 [20 | 330 [ 520 | 40 | 1300 a : a ea ae 18] 30 [own ra : a a ee ~~" : a r Fe ir it t Seas aa ae [aL ao aE ‘ 4 rn a 30] so [wah = = : ; z as | ¥ © " = a « T 13 {30 [ae | 74 To [190 F300 [460 T 740] 7200 T1900 Tia rm = rn 8 50] 60 | Hsl2 [vs vs 6 | * = v 2 s o o o o Z & z 2 2 eo ~~ | Continued) 141S 33455-1971 ‘TABLE 2 GAUGE TOLERANCES AND THEIR LOCATION FOR GAUGES FOR INSIDE MEASUREMENTS (HOLES) — Contd All values ace in erometar (#0) Nominal Sizes| Work Tolerance Grades as per ISO an : : up te over [2212 Symbais| 6 | 7 | 8 | 9 | 10, | 2 | 3] 14 | 15 | 16 7a Sefer aT 3 8a [aon [00 80 2 : " 7 Sa OO eee ee * 7 7 120 | 180 [owe] a= |e 7 0 ier om a ee oe a 2 2 2 zope ep pe 3 ‘0 7 1 [2s | <6] 92] 185290] a0 | 720 | 80 | vas0 | 2500 wae ts : 3 ny 2 veo | 250 ep n "7 = zope eee eae eT ea pe as [0 Tara er 30a 520 Pee aif Ha0 oe ozs wip. «+ | « 3 7 ra map <— r . 3 280 | 315 Y s 7 + ° o © [oz eee eae ee [ae eo fee a A we _[ ot 5 Ba vs foo Peete fs zp [oe bee [eae ee a OE was [98 3 ae 49) 500 Ppa fe = nl [oe eae ee ease eave aoe [isola z0m aisle went] onetS :3455- 1971 TABLE 3 GAUGE TOLERANCES AND THEIR LOCATIONS FOR GAUGES FOR OUTSIDE MEASUREMENTS (SHAFTS) (Clause 10.32) All values are In mlerometor (#m) Nominal Sizes| Work Tolerance Grades as per ISO lower [ang fambois] 5 | 6 | 7 | 8 | a | to] m | 12] 19] 4 | 15 | 16 ms ae 00 | a |780-| coo [600 2 s 0 20 ro ie | 30 | es |-75 | wo | 160 | 300] ceo [ 750) 2 2 3a * © 3 om | __ 07s 07s 1 22| 36 | se | 90 | 1m | m0 | 360_[ 00 | 900, 6 7s Tae va no [10 | 270 | a0 | 705 [00, 10 ica Tis ie 0 [a0 [320 T s20 | 240 [1300 fs 15 18 1 es 2 3a_| ex [oo _| seo [250380 [ 620 (1000-1600 30 me [ee E <6 [ao 7200 | 7800- 50 isla 38 ‘. (Continued) 16: 1S :3455 - TABLE 3 GAUGE TOLERANCES AND THEIR LOCATIONS FOR GAUGES FOR ‘OUTSIDE MEASUREMENTS (SHAFTS) — Contd ‘All values are in mlerometer( #m) fomira Sizes Work Tolerance Grades as per 150 sea [ee fmess] 8] of 7] ef] of wl n | fa] ul [6 ver | Bid Fn Se ae es 3 Te in eo | 120 epee |e fees leanne oe ce % a 5 1 78 | 25 | «0 | €3 |" yoo T 160 | 250 [400 [630 | 1000 | 1600 | 2500) me . “8 % 120 | 10 [reps oe | 3 = n n Toes ° a FE 10 | 280 See A 7 : fa [eee aan oem ewe | oe] oei| real aa ease Tae | aan 1-320 a1 [300 | an a00 250 | 318 afentas ise are = . Se aaa ee a wa a20 [360°] 370 [0 [ao | 200 | 3800 wre a of o ais | 400 | 7 “ z = zr oe ra toes el aL t iss | as0_| “oo | exo | 3m | 580 | 2500] coe wept e y 3 = coo | soo [wwe fs fs fs : : zoe Sof ae EXPLANATORY NOTE This standard was originally issued in 1966 with a view to introducing a uniform gauging practice in the country. The method-of specifying the tolerance for gauges and also the calculation of ‘gauge limits was based on the proposals then under consideration at the level of Technical Committee ISO/TC 3 Limits and Fits, In this revision, the gauging practice for inspection of plain workpieces has been elaborated in dotail and it is based on Draft ISO Recommendation No: 1938 ISO system of limits and fits: Part II Inspection of plain workpieces. In the present version, not only have the tolerances for the gauges been indicated but also the gauging principles have been enumerated and recommendations on the use of ‘gauges for various size ranges have been elaborated. The numerical values given in this standard aro expressed in terms of the various grades of tolerances provided for in IS : 919-1963, Those are, therefore, valid for the ISI system of tolerances only. However, all other requirements of a more general nature given in this standard may still be applied as a rule to any system of limits for plain workpieces. In the earlier version, not only the tolerances for the limit gauges were covered but also certain requirements on the surface finish hardness, etc, of the gauges were incorporated. Since these requirements are now being covered separately in Indian Standard Technical supply conditions for ‘gauges and measuring davices (under preparation ), these have been deloted in tha present revision. 7 Printed at Dee Kay Printers, New Deli India