Limitations and cautions
To legally and technically bind a manufacturer to these guidelines, the standard must be stated explicitly inside or near the drawing title block.
ISO 2768 is a widely used international standard that defines general tolerances for linear and angular dimensions, as well as geometrical tolerances (in its parts), for use on technical drawings when specific tolerances are not indicated. Its purpose is to simplify engineering documentation, ensure interchangeability of manufactured parts, and reduce unnecessary precision — and therefore cost — by providing broadly applicable default tolerances. This essay outlines the standard’s scope, structure, practical significance, application principles, advantages and limitations, and its role in modern manufacturing.
This article explores what ISO 2768-mK means, how to interpret its tables, and why it is essential for cost-effective manufacturing.
| Tolerance Class | up to 10 mm | over 10 up to 30 mm | over 30 up to 100 mm | over 100 up to 300 mm | over 300 up to 1000 mm | over 1000 up to 3000 mm | | :--- | :--- | :--- | :--- | :--- | :--- | :--- | | H | 0.02 | 0.05 | 0.1 | 0.2 | 0.3 | 0.4 | | | 0.05 | 0.1 | 0.2 | 0.4 | 0.6 | 0.8 | | L | 0.1 | 0.2 | 0.4 | 0.8 | 1.2 | 1.6 | Tolerance Iso 2768 Mk Pdf
The "M" in MK refers to the tolerance class for linear dimensions, which provides a medium level of tolerance. The "K" refers to the tolerance class for geometric tolerances, which provides a more stringent level of tolerance.
What is ISO 2768? | CNC Machining Tolerance Standards - Fictiv
Instead of cluttering a blueprint with hundreds of individual ±plus or minus
In the world of mechanical engineering and manufacturing, drawings are the language of communication. However, if every single dimension on a drawing had to be accompanied by a specific tolerance (e.g., $25.00 \pm 0.05$), technical drawings would become cluttered, difficult to read, and expensive to produce. Limitations and cautions To legally and technically bind
: Because it is an international ISO standard, parts designed in one country can easily be manufactured in another without communication friction. How to Apply It to a Technical Drawing
These deviations apply to the form and position of features under the "K" designation: Feature Type Tolerance Range (mm) Straightness/Flatness 0.05 (up to 10mm) to 0.8 (over 1000mm) Perpendicularity 0.4 (up to 100mm) to 0.8 (over 1000mm) 0.6 (up to 100mm) to 1.0 (over 1000mm) Circular Run-out 0.2 (fixed value) Why Use ISO 2768-mK?
If any specific dimension requires a tighter or looser tolerance than what is listed in the tables above, that specific dimension must be manually explicitly labeled (e.g., Conclusion
The term is a combination of the two parts, often abbreviated on engineering drawings. It stands for: The "K" refers to the tolerance class for
General mechanical assemblies where components need to fit together without precise interference or clearance needs. Common Mistakes to Avoid (ISO 2768 MK sdocuments)
There are three primary advantages to referencing ISO 2768-mK on a technical drawing:
Implementing ISO 2768-mk into your production workflow offers several critical benefits for engineers, machinists, and procurement teams:
Part 1 of the standard dictates permissible deviations for dimensions without specific tolerance callouts. The allowable variance depends entirely on the nominal size of the feature—larger dimensions are allowed larger variations.