1、CEN ENr22768-L 93 W 3404589 005215b 491 W EUROPEAN STANDARD EUROPISCHE NORM NORMEEUROPENNE EN 22768-1 April 1993 UDC 621.713.12 : 744.4 Descriptors: Machine components, dimensional tolerances, angular tolerances, untoleranced dimensions, dimensional deviations, specifications English version General
2、 tolerances - Part 1: Tolerances for linear and angular dimensions without individual tolerance indications (IS0 2768-1 1989) %lrances gnrales - Partie 1: %lrances pour dimensions linaires et angulaires non affectes de tolrances individuelles Tbleranzeintragung Allegemeintoleranzen - Teil 1: nleranz
3、en fr Lngen- und Winkelmage ohne einzelne (IS0 2768-1 : 1989) (IS0 2768-1 : 1989) This European Standard was approved by CEN on 1993-04-15. CEN members are bound to comply with the CENXENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a nation
4、al standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the Central Secretariat or to any CEN member. This European Standard exists in three official versions (English, French, German). A version in any
5、other language made by translation under the. responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Denmark, Finland, France, Germany, Greece, Icela
6、nd, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. CEN European Committee for Standardization Comit Europen de Normalisation Europisches Komitee fr Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels O 1993 Copyright reserved to
7、 CEN memberc Ref. No. EN 22768-1 : 1993 E CEN ENt227b8-1 93 9 3404589 0051157 328 9 Page 2 EN 22768-1 : 1993 Foreword In 1991, the International Standard IS0 2768-1 : 1989 General tolerances - Part 1: lblerances for linear and angular dimensions without individual tolerance indications was submitted
8、 to the CEN Primary Questionnaire procedure. Following the positive result of the CENCS Proposal, IS0 2768-1 : 1989 was submitted to the Formal Vote. The result of the Formal Vote was positive. This European Standard shall be given the status of a national standard, either by publication of an ident
9、ical text or by endorsement, at the latest by October 1993, and conflicting national standards shall be withdrawn at the latest by October 1993. According to the CENKENELEC Internal Regulations, the following countries are bound to implement this European Standard: Austria, Belgium, Denmark, Finland
10、, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland, United Kingdom. NCYTE. The European references to international publications are given in annex ZA (normative). Introduction All features on component parts always have a size a
11、nd a geometrical shape. For the deviation of size and for the deviations of the geometrical characteristics (form, orientation and location) the function of the part requires limitations which, when exceeded, impair this function. The tolerancing on the drawing should be complete to ensure that the
12、elements of size and geometry of all features are controlled, i.e. nothing shall be implied or left to judgement in the workshop or in the inspection department. The use of general tolerances for size and geometry simplifies the task of ensuring that this prerequisite is met. CEN EN*227b-L 73 340458
13、7 005LL58 2b4 Page 3 EN 22768-1 : 1993 General tolerances - Part 1 : Tolerances for linear and angular dimensions without individual tolerance indications 1 scope This part of IS0 2768 is intended to simplify drawing indica- tions and it specifies general tolerances for linear and angular dimensions
14、 without individual tolerance indications in four tol- erance classes. NOTE 1 - The concepts behind the general tolerancing of linear and angular dimensions are described in annex A. It applies to the dimensions of parts that are produced by metal removal or parts that are formed from sheet metal. N
15、OTES 2 These tolerances may be suitable for use with materials other than metal. 3 Parallel International Standards exist or are planned, e.g. see IS0 8062” for castings. This part of IS0 2768 only applies for the following dimensions which do not have an individual tolerance indication : a) linear
16、dimensions (e.g. external sizes, internal sizes, step sizes, diameters, radii, distances, external radii and chamfer heights for broken edges); b) angular dimensions, including angular dimensions usually not indicated, e.g. right angles (Wo), unless ref- erence to IS0 2768-2 is made, or angles of un
17、iform poly- gons; cl assembled parts. linear and angular dimensions produced by machining It does not apply for the following dimensions : a) reference to other standards on general tolerances; linear and angular dimensions which are covered by b) auxiliary dimensions indicated in brackets; c) theor
18、etically exact dimensions indicated in rectangular frames. 2 General When selecting the tolerance class, the respective customary workshop accuracy has to be taken into consideration. If srnal- ler tolerances are required or larger tolerances are permissible and more economical for any individual fe
19、ature, such toleran- ces should be indicated adjacent to the relevant nominal dimen- sionsl. General tolerances for linear and angular dimensions apply when drawings or associated specifications refer to this part of IS0 2768 in accordance with clauses 4 and 5. If there are gen- eral tolerances for
20、other processes, as specified in other Inter- national Standards, reference shall be made to them on the drawings or associated specifications. For a dimension between an unfinished and a finished surface, e.g. of cast or forged parts, for which no individual tolerance is directly indi- cated, the l
21、arger of the two general tolerances in question applies, e.g. for castings, see IS0 80621). 3 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of this part of IS0 2768. At the time of publication, the editions indicated were
22、 valid. All standards are subject to revision, and parties to agreements based on this part of IS0 2769 are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. Members of IEC and IS0 maintain registers of currently valid International Stan
23、dards. IS0 2768-2 : 1989, General tolerances - Part 2: Geometrical tolerances for features without individual tolerance indications. IS0 8015 : 1985, Technical drawings - Fundamental toleran- cing principle. 4 General tolerances 4.1 Linear dimensions General tolerances for linear dimensions are give
24、n in tables 1 and 2. CEN EN122768-L 93 3404587 0051159 IT0 Tolerance class Designation Description Page 4 EN 22768-1 : 1993 Permissible deviations for basic size range over over over 30 400 1000 2000 up to up to up to over over 3 6 6 30 120 400 1000 2000 4000 0.51 up to 3 up to up to upto upto 4.2 A
25、ngular dimensions General tolerances specified in angular units control only the general orientation of lines or line elements of surfaces, but not their form deviations. The general orientation of the line derived from the actual sur- face is the orientation of the contacting line of ideal geometri
26、cal form. The maximum distance between the contacting line and the actual line shall be the least possible value (see IS0 8015). f m C a) “IS0 2768“; f 0.3 I 0,5 - medium kO.1 IO.1 f 0.2 I 0.3 I0,5 f0,8 i1,2 I2 coarse I 0,2 ? 0,3 f0.5 i 0,8 f 1.2 I2 I3 f4 fine f0.05 k0.05 f0,l 1 +0,15 i0,2 - b) the
27、tolerance class in accordance with this part of IS0 2768. Tolerance class Designation Description f fine m medium C coarse V very coarse EXAMPLE Permissible deviations for basic size range over 3 up to 6 I0,2 f 0.5 I1 0.5) up to 3 over 6 i0,4 _+1 i2 IS0 n-m Tolerance class Designation I Description
28、The permissible deviations of angular dimensions are given in table 3. 6 Rejection Permissible deviations for ranges of lengths, in millimetres, of the shorter side of the angle concerned I over IO up to 50 1 over 50 up to 120lover 120 up to 400 1 up to IO over 400 Unless otherwise stated, workpiece
29、s exceeding the general tolerance shall not lead to automatic rejection provided that the ability of the workpiece to function is not impaired (see clause ,44). 5 Indications on drawings If general tolerances in accordance with this part of IS0 2768 shall apply, the following information shall be in
30、dicated in or near the title block : f m Table 1 - Permissible deviations for linear dimensions except for broken edges (external radii and chamfer heights, see table 2) Values in millimetres I 10 k OO30 f 0020 i 0010 i 05 fine medium V very coarse I30 I k 20 f 10 i 030 i0020 I V I verv coarse I - 1
31、 50.5 I i1 1 f1.5 I 12.5 I f4 1 f6 i8 I I li For nominal sizes below 0,5 mm, the deviations shall be indicated adjacent to the relevant nominal sizeis). I I C 1 coarse I fl“30 I f1 I iO“30 1 f015 I IOO10 I CEN EN*22768-L 93 m 3404589 005LLbO 912 m Page 5 EN 22768-1 : 1993 Annex A (informative) Conce
32、pts behind general tolerancing of linear and angular dimensions A.l General tolerances should be indicated on the drawing by reference to this part of IS02768 in accordance with clause 5. The values of general tolerances correspond to tolerance classes of customary workshop accuracy, the appropriate
33、 tolerance class being selected and indicated on the drawing ac- cording to the requirement for the components. A.2 Above certain tolerance values, there is usually no gain in manufacturing economy by enlarging the tolerance. For example, a feature having a 35 mm diameter could be manufac- tured to
34、a high level of conformance in a workshop with “customary medium accuracy“. Specifying a tolerance of f 1 mm would be of no benefit in this particular workshop, as the general tolerance values of f0,3 mm would be quite adequate. However, if, for functional reasons, a feature requires a smaller toler
35、ance value than the “general tolerances“, then that feature should have the smaller tolerance indicated individually adja- cent to the dimension defining its size or angle. This type of tolerance falls outside the scope of general tolerances. In cases where the function of a feature allows a toleran
36、ce equal to or larger than the general tolerance values, these should not be indicated adjacent to the dimension but should be stated on the drawing as described in clause 5. This type of tolerance allows full use of the concept of general tolerancing. There will be “exceptions to the rule“ where th
37、e function of the feature allows a larger tolerance than the general tolerances, and the larger tolerance will provide manufacturing economy. In these special cases, the larger tolerance should be indicated individually adjacent to the dimension for the particular feature, e.g. the depth of blind ho
38、les drilled at assembly. A.3 tages : Using general tolerances leads to the following advan- a) made more effective to the user of the drawing; drawings are easier to read and thus communication is b) the design draughtsman saves time by avoiding de- tailed tolerance calculations as it is sufficient
39、only to know that the function allows a tolerance greater than or equal to the general tolerance; c) the drawing readily indicates which feature can be pro- duced by normal process capability, which also assists quality engineering by reducing inspection levels; d) those dimensions remaining, which
40、have individually in- dicated tolerances, will, for the most part, be those control- ling features for which the function requires relatively small tolerances and which therefore may require special effort in the production - this will be helpful for production plan- ning and will assist quality con
41、trol services in their analysis of inspection requirements; e) purchase and sub-contract supply engineers can negotiate orders more readily since the “customary workshop accuracy“ is known before the contract is placed; this also avoids arguments on delivery between the buyer and the supplier, since
42、 in this respect the drawing is com- plete. These advantages are fully obtained only when there is sufficient reliability that the general tolerances will not be exceeded, .e. when the customary workshop accuracy of the particular workshop is equal to or finer than the general tolerances indicated i
43、n the drawing. The workshop should, therefore - find out by measurements what its customary workshop accuracy is; - accept only those drawings having general tolerances equal to or greater than its customary workshop accuracy; - check by sampling that its customary workshop accu- racy does not deter
44、iorate. Relying on undefined “good workmanship“ with all its uncer- tainties and misunderstandings is no longer necessary with the concept of general geometrical tolerances. The general geometrical tolerances define the required accuracy of “good workmanship“. A.4 The tolerance the function allows i
45、s often greater than the general tolerance. The function of the part is, therefore, not always impaired when the general tolerance is occasioially) exceeded at any feature of the workpiece. Exceeding the general tolerance should lead to a rejection of the workpiece only if the function is impaired.
46、CEN ENt22768-II 93 D 3404589 OOSLLbL 859 Page 6 EN 22768-1 : 1993 Annex ZA (normative) Normative references to international publications with their relevant European publications This European Standard incorporates by dated or undated reference, provisions from other publications. These normative r
47、eferences are cited at the appropriate places in the text and the publications are listed hereafter. For dated references, subsequent amendments to or revisions of any of these publications apply to this European Standard only when incorporated in it by amendment or revision. For undated references the latest edition of the publication referred to applies (including amendments). Publication IS0 2768-2 IS0 8015 Title EN/HD General tolerances - Part 2: Geometrical EN 22768-2 tolerances for features without individual tolerances indications lkchnical drawings - Fundamental tolerancing principle
