Tolerances for angles also depend on the length of the shorter leg (e.g., ± 30' for lengths up to 10mm). Broken Edges:
Linear tolerances scale with the size of the dimension. Larger features are allowed more variation than smaller features because they are harder to measure and control during manufacturing.
By using a globally understood standard, ISO 2768 eliminates ambiguity, ensuring that designers, manufacturers, and inspectors are aligned even when working across different countries or companies. The standard is divided into two parts that work together to cover both size and geometry:
When manufacturing a mechanical part, achieving absolute perfection in dimensions is physically impossible. Minor variations always occur due to tool wear, machine vibrations, and material expansion. To ensure parts fit together without requiring expensive, hyper-precise measurements for every single dimension, engineers use general tolerances.
In manufacturing and mechanical engineering, technical drawings must specify exactly how much variation is allowed for every dimension. Specifying individual tolerances for hundreds of dimensions on a single drawing is incredibly time-consuming and creates cluttered, unreadable blueprints. general tolerance iso 2768-mk
6 to 30 mm: ±0.5 mm
The tolerance for a linear dimension depends on its and the chosen tolerance class (f, m, c, v). All values below are in millimeters (mm) .
ISO 2768 is an international standard that defines general tolerances for linear and angular dimensions, as well as geometric tolerances for features without individual tolerance indications. It simplifies technical drawings by eliminating the need to specify tolerances for every single dimension. is a combination of two parts of the standard:
The "m" class defines how much a length or diameter can vary based on its size. Nominal Size Range (mm) Tolerance for "m" (mm) over 3 to 6 over 6 to 30 over 30 to 120 over 120 to 400 over 400 to 1000 The General CNC Machining Tolerance: ISO 2768-mk Tolerances for angles also depend on the length
Implementing this standard provides several clear operational advantages for engineering teams and machine shops alike:
If a specific feature requires higher precision than the general 'mK' level, the designer must explicitly label that individual dimension with its own tolerance. Summary of Benefits Cleaner Drawings: Reduces visual clutter by removing common tolerance ranges. Standardization:
Under ISO 2768-1, there are four tolerance classes: fine (f), medium (m), coarse (c), and very coarse (v). The , which is the industry standard for conventional CNC machining, milling, and turning.
While ISO 2768 is the standard in Europe and Asia, you may encounter other systems: By using a globally understood standard, ISO 2768
Because ISO is globally recognized, a drawing designed in Germany using ISO 2768-mK can be accurately interpreted and manufactured by a machine shop in Japan or the United States without communication barriers. Important Exceptions and Limitations
Understanding General Tolerance ISO 2768-mk In the world of precision manufacturing, specifying a tolerance for every single dimension on a technical drawing is both time-consuming and prone to error. is an international standard designed to solve this by providing "general tolerances" that act as a default for any dimension without an individual specification.
: Inspection teams use universal standard templates to accept or reject batch parts. 6. How to Indicate ISO 2768-mk on Drawings