(Parte 1 de 3)

m m-

E m m m

Aft o` 5 c CL

-m~ o m v m

Beuth Verlag GmbH, Berlin, has the exclusive right of sale for German Standards (DIN-Normen).

April 1991

General tolerances for Iinearand angular dimensions and geometrical=.tolerances (notto be used for.new destgns).'-j';,,

DIN 7168

Allgemeintoleranzen; Langen- and Winkelma8e,Form and=Lage& ' Supersedes May 1981

.'7' 1 edition of DIN 7168

Part 1 and July 1986

This standard is not to be used for new designs. General tolerances for these are now covered by ISO 2768 Parts 1 and 2. See also clause 1 and the Explanatory notes.

In keeping with current practice in standards published by the International Organization for Standardization (ISO), a comma has been used throughout as the decimal marker.

1 Scope

This standard is intended to ensure that all drawings prepared to date in which general tolerances have been specified on the basis of DIN 7168 will remain intelligible and be interpreted correctly, and also to inform the user of this standard that, for all new designs, tolerances are to be specified on the basis of ISO 2768 Parts 1 and 2.

2Field of application

General tolerances as specified in this standard are

• applicable for the dimensions of parts produced by metal removal (i.e. chip removal)'), unless this involves specia! manufacturing processes for which other standards speci- fying general tolerances apply.

General tolerances as specified here shall apply when reference is made to this standard in drawings or associated documents (e.g. delivery conditions) in accordance with clause 5.

If special general tolerances are specified in accordance with other standards (cf. page 6), the standards concerned shall be indicated on the drawing or in the associated documents. If, in cases where production specifications contain references to more than one standard on general tolerances, there is any doubt as to which standard is to apply for a given linear or angular dimension, then the standard specifying the larger tolerance shall be deemed

Accordingly, a dimension between an unfinished and a finished surface on a blank (e .g. on a casting blank or

•forging blank), for which no individual tolerance has been indicated, will be required to meet the general tolerance given in the relevant standard on blanks, provided that is indeed the larger tolerance . However. for a dimension between two finished surfaces, the general tolerance specified in DIN 7168 shall always apply.

Production specifications in which linear or angular dimen- sions (but not auxiliary dimensions) appear without individually indicated tolerances shall be considered incomplete if there is no reference, or inadequate reference, to general tolerances.

General tolerances as specified in this standard apply for:

a) linear dimensions, such as external sizes, internal sizes, step sizes, diameters, clearances (cf. table 1), external radii and chamfer heights for broken edges (cf.

table 2) ; b) angular dimensions (cf. table 3), both those indicated and those not usually indicated on drawings, such as 90° angles or the angles of regular polygons:

c) linear and angular dirrfeensions produced by machining assembled parts:

d) workpiece features for which no individual tolerances of form and position are indicated.

General tolerances as specified in this standard do not apply for:

a) linear and angular dimensions and workpiece features for which tolerances have been individually indicated; b) linear and angular dimensions and workpiece features for which other standards on general tolerances are specified in drawings or associated documents ; c) auxiliary dimensions enclosed in brackets (cf . DIN 406

Part 2); d) theoretically exact dimensions enclosed in rectangular frames as specified in ISO 1101; e) angular dimensions on circular graduations; f) 90° angles, not indicated on the drawing, between lines forming coordinate axes:

linear and angular dimensions produced by the assembly of parts; h) workpiece features which are not produced by removal of material, in accordance with the indication of a semifinished product on drawings.

') For concepts relating to manufacturing processes. see DIN 8580.

Continued on pages 2 to 7

DIN 7168 Engl . Price group 8

Page 2 DIN 7168

Table 1. Permissible deviationsfor lineardimensions, except for external radii and chamfer heights

Table 2. Permissible deviations for external radii, r

(cf. figure1 for example), and chamfer heights, h (cf. figure 2 for example)

General tolerances for angular dimensions apply irrespective of the actual dimensions of the lengths, i.e. the angular deviations may occur both on workpieces with maximummaterial sizes and on workpieces with minimum-material sizes. The upper and lower deviations do not limit the form deviations of the legs or surfaces forming the angle.

Note. In the case of workpieces exhibiting deviations of form, the angle is defined by the direction of the straight lines or planes applied to the two angle legs under the minimum material conditions (cf.

ISO 1101 for the definition of the minimum condition) .

Table 3. Permissible deviations for angular dimensions

4General geometrical tolerances

4.1 Tolerancingprinciple as specified in ISO 8015

General tolerances based on the tolerancing principle specified in ISO 8015 are only to be applied when the drawing concerned contains the reference 'Tolerancing to ISO 8015'. Where that is the case. the general geometrical tolerances (i.e.the tolerances of form and position) apply independently of the actual local sizes of the workpiece feature. Each individual tolerance requirement must be met. The general geometrical tolerances may thus also be applied even if the features are everywhere at their maximum material size. For fits, the envelope requirement must also be specified, and this shall be individually indicated on the drawings (cf. Explanatory notes).

The general tolerances on straightness and flatness shall be as specified in table 4. Tolerances on straightness shall be selected from the table on the basis of the length of the corresponding tine, while, for flatness tolerances, selection shall be based on the longer lateral length of the surface, or on the diameter of the circular surface.

The general tolerance on circularity shall be equal to the numerical value of the diameter tolerance, but in no case shall it be greater than the respective tolerance on radial run-out given in table 6 (cf. Explanatory notes).

Tolerance class for

Permissible nominal over 3 up to 6 deviations, sizes, over 6 up to 30 in in m.

(Parte 1 de 3)