2857 73 4853903 0034683 5 r INTERNATION AI STANDARD @ 2857 ‘*Xe INTERNATIONAL ORGANIZATION FOR STANOARDIZ4TION MElKnYHAPOnHAR OPrAHM3AUHR no CTAHAAPTMSAUIIM ORGANISATION INTERNATIONALE DE NORMALISATIO[.]
2857-73 r STANDARD AI INTERNATION 4853903 0034683 @ 2857 ‘*Xe - INTERNATIONAL ORGANIZATION FOR STANOARDIZ4TION MElKnYHAPOnHAR OPrAHM3AUHR no CTAHAAPTMSAUIIM ORGANISATION INTERNATIONALE DE NORMALISATION Ground thread taps for I S metric threads of tolerances 4H to 8H and 4G to 6G coarse and fine pitches - Manufacturing tolerances on the threaded portion First edition - 1973-12-01 UDC 621.993 Ref No I S 2857-1973 (E) Descriptors : tools, taps, screw threads, dimensional tolerances Price based on 13 pages ~ 2857-73 I 0014684 I FOREWORD IS0 (the International Organization for Standardization) is a worldwide federation of national standards institutes (IS0 Member Bodies) The work of developing International Standards is carried out through IS0 Technical Committees Every Member Body interested in a subject for which a Technical Committee has been set up has the right to be represented on that Committee International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work Draft International Standards adopted by the Technical Committees are circulated t o the Member Bodies for approval before their acceptance as International Standards by the IS0 Council International Standard IS0 2857 was drawn up by Technical Committee ISO/TC 29, Small tools, and circulated to the Member Bodies in August 1972 It has been approved by the Member Bodies of the following countries : Austria Belgium Chile Czechoslovakia Egypt, Arab Rep of France Germany India Ireland Israel Italy Netherlands New Zealand Poland Romania South Africa, Rep of Switze r1and Thailand Turkey United Kingdom The Member Bodies of the following countries expressed disapproval of the document on technical grounds : Japan Sweden O International Organkation for Standardization, 1973 o Printed in Switzerland CONTENTS Page References Basicdata 3.2 Thread profile of tap 3.3 Tolerance classes of taps Scope and field of application 3.1 Thread profile of nuts 3.4 Calcdation of tap thread dimensions of classes and Pitch diameter d2 Minor diameter of tap d , Tolerance on the angle (Y and half angle d2 of thread Cumulative pitch error T,, over any number of threads 4 Manufacturing tolerances on tap threads 4.1 4.2 4.3 4.4 4.5 Majordiameterd Designation and marking of taps 6 6 Example of calculation of the dimensions of the threaded portion of a tap Annexes A Ground thread taps for I S metric threads of coarse pitch B Ground thread taps for I S metric threads of fine pitch 10 Ground thread taps for I S metric threads of tolerances 4H to 8H and 4G to 6G coarse and fine pitches - Manufacturing tolerances on the threaded portion REFERENCES SCOPE AND FIELD O F APPLICATION This International Standard specifies the manufacturing tolerances on the threaded portion of taps for producing the I S metric threads of tolerance classes 4H to 8H and 4G to 6G as defined in ISO/R 965/1 to III (excluding, consequently, classes 7G and 8G considered as usually produced with ground thread taps) It is valid for the short taps specified in ISO/R 529 as well as for any other kind of ground thread taps with the same diameters and pitches The internal threads produced with those taps are conventionally designated by the simplified denomination of "nut" in agreement with the word used in ISO/R 965 for the general designation of all internal threads Annexes A and B give, for all threads with coarse and fine pitches, the manufacturing tolerances on the threaded portion of taps for the following classes of nuts : ISO/R 965/1, IS0 general purpose metric screw threads Tolerances - Principles and basic data ISOIR 96511I, IS general purpose metric screw threads Tolerances - Limits of sizes for commercial bolt and nut threads - Medium quality ISO/R 965/1 I I, IS0 general purpose metric screw threads Tolerances - Deviations for constructional threads 3.1 Thread profile of nuts : see figure 4G and 5G - 6G ISO/R 724, IS general purpose metric screw threads Basic dimensions BASICDATA 4H and 5H - 6H - 7H and 8H and ISO/R 529, Short machine taps and hand taps P I + D = nominal diameter c ' D1 = basic minor diameter D2 = pitch diameter \ P = pitch of thread Basic profile- (Y = included angle of thread H = height of fundamental triangle E l = minimum clearance, zero for H deviation positive for G deviation - Tol m -C = minor diameter tolerance To2 = pitch diameter tolerance E C a FIGURE 1 3.2 Thread profile of tap : see figure P /’ / -b d = permissible minimum major diameter Js = minimum clearance on major diameter d, = minimum pitch diameter d2 max = maximum pitch diameter / a” = nominal diameter d2 = D2 = pitch diameter / ‘1 d =D ’‘ Es = upper deviation of pitch diameter Em = lower deviation of pitch diameter Td2 FIGURE2 = tolerance on pitch diameter 3.3 Tolerance classes of taps 3.3.1 Tolerance on pitch diameter For the production of nut classes of the following classes : The value for the tap pitch diameter tolerance Td2 is the same for a l l three classes 1,2 and : it is equal to 20 % of t 4H - 5H - 6H - 7H - 8H with zero minimum clearance, 4G - 5G - 6G with positive minimum clearance, three tolerance classes have been accepted : + 0,l t for tap class : + 0,3 t for tap class : + 0,5 t for tap class : Class - Class - Class The tolerances of these three classes are determined as indicated hereafter, in terms of a tolerance unit t , the value of which is equal to the pitch tolerance value T o ,grade of the nut (extrapolatedup to pitch 0.2 mm) : t= The position of the tolerance of the tap with respect to the basic pitch diameter results from the lower deviation Em, the values of which are (see figure 3) : T D grade ~ of the nut 3.3.2 Choice of tolerance class of the tap with respect to the class of thread to be produced NUTS Unless otherwise specified, the taps of classes to will generally be used for the manufacture of nuts of the following classes : - Class : for nuts of classes 4H and 5H - Class : for nuts of classes 6H and also 4G and 5G TAPS - Class : for nuts of classes 7H 4H 5H* Pitch diameter of basic profile FIGURE - 8H and also 6G This correspondance has, however, only an indicative nature, since the accuracy of tapping can vary as a function of a series of factors such as : the material to be tapped, the condition of the machine tool, the tapping attachment, the tapping speed, the lubricant, etc Users are therefore recommended to select in each case the most suitable class of tap for the manufacture of the required class of nut 3.4 Calculation of tap thread dimensions of classes 1,2 and Minimum tolerance on tap major diameter d = D of tap Class of d = D nominal diameter of tap Js = 0,4 all t* d = D + Js Tolerance on tap pitch diameter d2 Em = 0,l t* Es = 0,3 t* d, = d2** -!- Em d, max = d * * + Es Em = 0,3 t* Es = 0,5 t * , d2 =d2** f Em d , max = d * * 4-Es - Em = 0,5 t* Es = 0,7 t* I d, = d2** iEm d, max = d2** f Es Tolerance on tap minor diameter I all A ? t t No tolerance is specified on this diameter The thread root is generally, but not mandatorily, with a rounded form and the profile of the radius blending with the flanks of the thread should lie, in principle, under the line AB which corresponds with the internal diameter D l of the basic I S profile * t = tolerance unit = To2pitch tolerance, grade of the nut The values are given in ISO/R 965/1, section ** The ú2 values correspond t o the values of the pitch diameter D2 of the nut in conformity with ISO/R 724 TABLE - Minimum deviation Js in micrometres THREADS Nominal diameter 4.1 Major diameter d UD The minimum major diameter d shall be equal to the nominal diameter D of the nut, plus deviationJs Deviation JS shall be greater than or equal to 0,4 t.* to over inciand uding I Minimum deviation Js Pitch 0.35 + + + + + + 0.4 + 02 The maximum major diameter d max is not fixed and is left to the manufacturer's judgement 0.99 1.4 0,25 0.3 0.2 0.25 1.4 2.8 2.8 5.6 -,- II 0.45 I 0.6 +lI I 5.6 1.2 t 0.35 I + + + 20 22 24 21 24 27 28 30 28 36 +38 0.8 0.75 I I + 40 t 42 + 47 1.25 + 50 + + 50 2.5 +68 + 72 + 1.5 +64 I I 1.25 I I - I 56 11,2 22,4 45 -1 4.5 + 94 + 100 1.5 +68 45 t = tolerance unit = io,, pitch tolerance, grade of the nut (See ISO/R 965/1 The values given for the pitch of 0,2have been obtained by extrapolation.) A < 90 I I 53 I + 76 + 90 + 100 + 106 4.2 Pitch diameter d2 The maximum and minimum permissible values on the pitch diameters, d2 max and d2 min., of the taps are calculated in terms of the deviations Ern and Es given in Table Nominal diameter TABLE -Values of deviations Em and Es in micrometres over Nominal diameter over I Pitch I I Deviations for pitch diameters Em and Es Pitch up t o and icluding classes Deviations for pitch diameters Em and Es - 1,25 1,5 11.2 22,4 1.75 0.99 25 1.5 1.4 22.4 45 + + 42 + 14 + 45 + 15 + 48 + 16 + 51 + 17 +54 18 + + 40 + 21 1.5 2.8 63 + 38 + 70 + 42 + 75 + 45 + 80 + + 88 63 + + 98 70 t 105 + 75 +112 80 48 + 85 51 +119 + 85 90 +54 +I26 +90 + 95 + 57 + 112 + 67 + 133 + 95 + 157 + + + + + 16 4,5 - + + 13 + 48 +54 18 + + 64 i67 + 22 + 71 + 24 + 75 + 25 + 51 + 17 + 57 + 19 + 67 + 22 + 75 + 25 + 80 + 27 + 75 + 133 + 80 5,5 +84 28 + +140 84 +196 +140 + 30 +150 + 90 +210 +150 90 t 38 13 3,5 45 5.6 - + + 90 +125 +112 +175 +125 + 186 +133 I S 2857-1973 (E) ~ 2857-73 ~ 4853903 0014691 fi 4.3 Minor diameter of tap dl DESIGNATION AND MARKING OF TAPS No tolerance is specified on this diameter which is governed by the wear on the tool used to produce this thread The taps shall bear, after their dimensional designation (as indicated in ISO/R 5291, the nominal diameter and, if necessary, the pitch of the thread, and the symbol I S followed by the class of the tap, a dash being placed before the I S symbol The profile of the radius blending with the flanks of the thread should however lie, in principle, under the line AB which corresponds with the internal diameter D , of the basic I S profile Examples : For an M6 coarse pitch tap of class : M - IS0 For an M 20 tap with pitch of of class : M20X - IC0 4.4 Tolerance on the angle thread (Y and the half-angle d2 of The values for these tolerances are based on the pitch of the thread; they apply both to the anglea and to the half-angle ( ~ / and shall be in accordance with the values of Table TABLE - Tolerances on the angles Pitch ranges P I I I I Tolerances on I Over Up to and including I I 0.2 I I angle (u and 112 angle (u12 0.4 I I I ? 40’ i15’ 4.5 Cumulative pitch error T, over any number of threads This error i s fixed a t f 0,05 % of the considered measuring length with a minimum of f 0,008 mm I EXAMPLE OF CALCULATION OF THE DIMENSIONS OF THE THREADED PORTION OF A TAP GROUND THREAD TAPS FOR I S METRIC PITCHES Example for an M 14 tap, class Tap designation M 14- I S Tap characteristics D = nominal diameter = 14 mm Pitch = mm Threaded length = 30 mm Basic data taken from ISO/R 724 12,701 mm + Js (0.4 t ) 14,000 mm 0,068mm d2 = D2 = Minimum major diameter (d min.) d = D D= Js (0,4 t ) = d = 14,000 Minimum pitch diameter (d2 min.) (see 4.1 d2 = d2 +Em (0,3t ) d2 (basic) = Em (0.3 t ) = d2 Maximum pitch diameter, (d2 max.) + 0,068 = 14,068 mm = 12,701 d2 max = d2 12,701 mm 0,051 mm + 0,051 = 12,752 mm (see 4.2) + Es (0,5 t ) d2 (basic) = 12,701 mm Es (0.5 t ) = 0,085 mrn d2 rnax = 12,701 + 0,085 = 12,786 mm (see 4.2) Minor diameter Not specified (see 4.3) Tolerance on the angle (ar) or half-angle ( ) For a pitch of mm ísee 4.41 of pitch Cumulative pitch error ïpover any number of threads t = TD2 : pitch tolerance, grade of the nut (See 3.4.) ísee 4.5) ANNEX A GROUND THREAD TAPS FOR I S METRIC THREADS OF COARSE PITCH Dimensions and manufacturing tolerances for the threaded portion of taps of : Class of taps All classes Thread Major diameter Class (for classes 4H and 5H of nuts) Basic Designation d Pitch nominal P Class (for classes 6H, and 4G and 5G of nuts) - Class (for classes 7H and 8H, and 6G of nuts) deviation diameter drnin 0.4 t d2 0.25 * - M 1.4 M 1,6 M 1.8 0.3 0.35 M M 2,2 + 0,027 + 0,028 0.4 - 2.2 0.45 M 0.75 2,028 I 1,740 + 0,030 + 0,038 + 0.040 5,040 4.480 1.25 M 9 M 10 10 M 11 11 M 12 12 M 14 14 M 16 16 M 18 18 M 20 20 M 22 22 M 24 24 M 27 27 M 30 30 M 33 33 M 36 36 Minor diameter of tap M 39 39 No tolerance is specified on this diameter The thread root is generally, but not mandatorily, with a rounded form and the profile of the radius blending with the flanks of the thread, should lie, in principle, under the line AB which corresponds with the internal diameter D l of the basic I S profile M 42 42 M 45 45 M 48 48 Cumulative pitch error Tp over any number of threads This error is fixed at f 0,05 % of the considered measuring length with a minimum o f f 0,008 rnm + 0,050 + 0,056 1.75 + 0,068 + 0,085 3.5 + 0,090 + 0,094 4.5 + 0,100 + 0,106 M 52 52 M 56 56 M 60 60 M64 64 M 68 68 5.5 + 0,112 + 0,120 - Dimensions in millimetres I Min deviat Em + 0,006 d2min 1,211 + 0,007 I I + 0,009 I 1-1 1,747 I o,o13 2,683 3.1 19 4,490 max ld2max I Min deviat + 0,016 I o,o21 o,o22 14,718 18,394 I o,o25 + 0,027 22,072 25.072 27.749 30.749 39,102 42.102 44,779 48.779 52,456 56,456 max d2 ú2 Td2 id2 Id max d2 d on Q andQ/;! nomina +0,011 1.2 I + 0,014 I 1,761 I + 0,016 I I + 0,018 I + 0,019 *l I + 0,020 I + 0,023 1,223 2,699 3,137 1,235 I f I I I + 0,024 I + 0,027 I + 0,030 + 0,035 0,028 I 0,032 0,034 10.068 + 0,036 + 0,043 0,042 I 10.91 0,048 2,699 I + 0,016 I 2,715 3,137 I + 0,018 I 3,155 4,510 I + 0,040 I + 0,045 + 0,019 4,042 4,530 I + 0,050 1-1 + 0,047 22.1 15 0,050 27.794 30.794 39,152 42.1 52 + 0,053 44,832 + 0,056 52.51 48,832 56.51 60,133 60,193 64,133 64.193 18,430 + 0,071 f 0,075 + 0,080 27,794 36,473 39,152 42.1 52 44.832 48,832 + 0,036 I I 18,466 9,096 10.096 10,943 0,085 1-1 t 0,042 27,839 I 30,839 36,520 + 0,045 t 0,047 + 0,050 + 0,053 + 0,060 + 0,090 18,466 4,550 I 5,433 + 0,024 6.433 7,276 + 0,025 I+ I 0,028 I 39,202 42.202 44.885 I I II + 0,032 II 1 + 0,036 t 8.276 9,124 10,124 10,975 25' II II :: F" 12 16,502 f 20 ' 20 18,502 22 + 0,106 I + 0.1 12 + 0.1 18 1+ 0,125 i 0,133 + 0,045 1+ E l+ 39,202 42.202 + 0,150 0,050 39,252 42,252 I C15' 0,053 + 0,056 + 0,140 64.253 2.2 4,5 I + 0,020 I 7,251 0,080 I k 30' + 0,019 4,530 E I 20,502 + 0.056 64.193 2,731 3,173 W:::1 30,794 + 0.084 + 0,090 10,943 1 I 0,067 f0.016 I + 0,018 I 6,409 I I 0,032 20,430 + 0,064 25.1 15 I t 0,034 16,430 + 0,054 18,430 36.473 10,068 2,715 3,155 5,409 + 0.070 0,028 10,911 +I H I I + 0,048 I + 0,020 9,068 + 0,051 14,752 I+ I + 0,045 1.6 0,038 8,226 1.4 IGI I 7.226 0,025 I 6,385 40' I + 0,021 + 0,029 4,510 + 0,012 I +0,014 I I I I+ I H 36,426 Toler H H I 1 1-1 + 0,024 10,040 10,879 + 0.01 + 0,018 6.362 deviat Em I t 0,012 1,223 I + 0,018 + , ~ 0,020 + 7,201 8,201 + 0,014 + id2 I Toier lzl 1-1 1 + I I+ I + I l: %zz 1-1 + x + I+ I I+ I I+ I I+ - + I E l 11-1 + + 0,012 + Toler qqZ710.;, I I + 0,010 + I El I + I I I i Pitch diameter 60,253 64.253 I+ I 0,060 I I I33 60 60,313 64.313 ANNEX% GROUND THREAD TAPS FOR I S METRIC THREADS OF FINE PITCH Diameters of to 32 mm Dimensions and manufacturing tolerances for the threaded portion of taps of : II All CI- C l a u of taps Class (for classes 4H and 5H of nuts) Designation d Pitch nominal P Min' deviation I I I Major diameter Thread Basic pitch diameter Min Class (for classes 6H,and 4G and 5G of nuts) Class (for classes 7H and 8H, and 6G of nuts) c M 2.2X0.25 M 2.5 X X 0.25 2.2 0.35 2.5 - 0.35 3.5 4.5 0.5 1,670 =&2E 3.028 X I + 0,024 _- - M 1,821 ~ 0.35 - M I - 0.5 I I 4,032 2,773 I I 3,675 + 0,032 M X (M X 0.75 l I I 5,532 5.5 0.75 + 0,042 I 5,175 5,513 6,513 7.350 8,350 9,350 9,188 1.25 11,188 - 11,026 1.5 1.25 1.5 M20 X 1.5 1.5 M22 X 1.5 1.5 - + 0.068 II 22.068 + 0.064 24,064 1.5 - II 20.701 I 23,026 'M25 Minor diameter of tap No tolerance is specified on this diameter The thread root is generally, but not mandatorily, with a rounded form and the profile of the radius blending with the flanks of the thread, should lie, in principle, under the line AB which corresponds with the internal diameter D l of the basic I S prof ile Cumulative pitch error Tp over any number of threads This error i s fixed at $ 0.05 % of the considered measuring length with a minimum of 0,008 rnrn * -I I M 27 M27 X 1,5 1.5 X 15 27 X2 1.5 1.5 lm1 M3û lM3û Xl,5 X3 I 30 + + 0,064 1.5 - 30,064 30.072 28,701 + 0,085 I 30,085 28,051 1.5 - + 0.072 29,026 31,026 30,701 Dimensions in millimetres I Class Class Class Pitch diameter Min deviat Em d2 O 875 + 0,016 I + 0,018 ] 31,042 30,719 Toler Td2 rnax Min deviat d2 max Em d, Toler max Toler Td, d, max Min deviat Em d2 Toler Td2 rnax d on