Instead of writing ± values for every single hole or edge, one note covers everything non-critical.

While ISO 2768-mK is incredibly versatile, it is not a blanket solution for every dimension on a print. Keep the following rules in mind:

Linear dimensions include external sizes, internal sizes, steps, diameters, and distances. Nominal Size Range (mm) Permissible Deviation (mm) for Class Over 3 to 6 Over 6 to 30 Over 30 to 120 Over 120 to 400 Over 400 to 1000 Over 1000 to 2000 Over 2000 to 4000 External Radii and Chamfer Heights

(ISO 2768-2), which covers geometric tolerances such as straightness, flatness, and symmetry. The "K" is one of three precision classes (H, K, and L). ISO 2768-m: Linear and Angular Dimensions

For angular dimensions, the general tolerances under class "m" depend on the length of the shorter leg of the angle: Length of Shorter Leg (mm) Permissible Deviation for Class "m" 120 to 400 2. The Uppercase "K" (Geometrical Tolerances)

The designation "ISO 2768-mK" is split into two distinct parts, each governing a different aspect of geometric and dimensional accuracy.

: For class K, the general tolerance for symmetry is for all nominal lengths up to

What are you using? (CNC machining, sheet metal, injection molding?) What is the primary material of the part? Share public link

Tolerances for linear and angular dimensions.

Among its various classifications, is one of the most widely specified standards globally. This comprehensive guide breaks down what ISO 2768-mK means, its component parts, and how to apply it to your manufacturing projects. What is ISO 2768?

| Tolerance Class (ISO 2768) | Part 1 (Linear) | Part 2 (Geometry) | Typical Use | | :--- | :--- | :--- | :--- | | | Tightest | Medium | Precision instruments | | m (Medium) | Standard | – | General machining (default) | | c (Coarse) | Loose | – | Fabrications, non-critical | | v (Very coarse) | Very loose | – | Castings before machining |

In manufacturing, perfection is impossible. Every part coming off a CNC mill, lathe, or sheet metal bender will have tiny variations in size and shape. If engineers had to specify an individual tolerance for every single dimension on a complex blueprint, drawings would become unreadable, and design time would skyrocket. This is where comes in.

A feature for establishes a "medium" precision standard for parts, ensuring they are manufactured within acceptable limits for both size and shape without requiring individual tolerance callouts for every dimension. The designation breaks down into two parts:

What are you using (e.g., CNC milling, 3D printing, sheet metal)? Are you dealing with any critical mating parts ? Share public link

These limits are selected based on the length of the corresponding line or the larger surface dimension. Nominal Length Range (mm) Permissible Deviation (mm) for Class Over 10 to 30 Over 30 to 100 Over 100 to 300 Over 300 to 1000 Over 1000 to 3000 Perpendicularity

"Medium" (m) and "K" classes represent standard workshop accuracy. Forcing tighter tolerances where they aren't needed increases manufacturing time and cost.

To make this standard legally binding for a project, it must be explicitly cited on the technical drawing. This is usually done inside or right next to the title block using the following text: When to Override the Standard