ISO 2768 Part 1 is intended to simplify drawing indications and it specifies general tolerances for linear and angular dimensions without individual tolerance indications in four tolerance classes. It applies to the dimensions of parts that are produced by metal removal or parts that are formed with sheet metal fabrication.

General tolerance ISO 2768 does not specify where to use these tolerances. As per design requirements and manufacturing capability tolerance class is defined. For example: For sheet metal parts ISO 27 68 – mk is used. And for machined components ISO 27 68 – fh can be used. In the above example “m” and “k” has defined the tolerance class. General Tolerances to DIN ISO 2768. The latest DIN standard sheet version applies to all parts made to DIN standards. Variations on dimensions without tolerance values are according to 'DIN ISO 2768- mk'. GENERAL TOLERANCES FOR LINEAR AND ANGULAR DIMENSIONS (DIN ISO 2768 T1) LINEAR DIMENSIONS: Tolerance class designation (description).

ISO 2768 Part 1 only applies to the following dimensions which do not have an individual tolerance indication:

a) linear 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 (90°). unless reference to ISO 2768-2 is made, or angles of uniform polygons;

Iso 2768 Mk Standard

c) linear and angular dimensions produced by machining assembled parts.

It does not apply for the following dimensions:

a) linear and angular dimensions which are covered by reference to other standards on general tolerances;

b) auxiliary dimensions indicated in brackets;

c) theoretically exact dimensions indicated in rectangular frames.

Note:

1. These tolerances may be suitable for use with materials other than metal.

2. When selecting the tolerance class, the respective customary workshop accuracy has to be taken into consideration.

3. Smaller or larger tolerances should be indicated adjacent to the relevant nominal dimensions.

Iso 2768 Mk Pdf

4. General tolerances specified in angular units control only the general orientation of lines or line elements of surfaces, but not their form deviations.

Iso 2768-mk Vs Iso 2768-mh

5. If general tolerances in accordance with ISO 2768 shall apply, the information shall be indicated in or near the title block, such as ISO 2768-m.