ISO 2768-1 defines four tolerance classes: f (fine), m (medium), c (coarse), and v (very coarse). The "m" designation means your design will follow medium tolerance limits.
is the go-to default for general machined parts in most workshops. It balances cost, inspectability, and functionality. Always verify that your feature tolerances (especially form) are adequate for assembly – if not, add explicit GD&T.
The standard represents the "Medium" standard of modern manufacturing. It balances manufacturing cost with functional reliability. By applying this standard, companies reduce drawing clutter, minimize misinterpretation, and ensure that parts are manufactured to a consistent, acceptable quality level.
If you are working with a (like plastics) that might require different tolerance considerations.
: For class K, the general tolerance for symmetry is for all nominal lengths up to general tolerance iso 2768-mk
The lowercase letter represents the tolerance class for linear dimensions (lengths, radii, diameters) and angular dimensions. ISO 2768-1 defines four accuracy classes: f – Fine m – Medium c – Coarse v – Very Coarse
Set at 0.6 mm for features up to 300 mm, increasing to 1.0 mm for larger features. Circular Run-out: Generally specified as 0.2 mm. Why Use ISO 2768-mK?
For linear measurements like external/internal sizes, heights, and distances. Nominal Range (mm) Tolerance (± mm) 120 to 400 400 to 1000 Geometric Tolerances (Class K)
| Nominal Length Range | Tolerance (mm) | |----------------------|----------------| | ≤ 10 | 0.02 | | >10 – 30 | 0.05 | | >30 – 100 | 0.1 | | >100 – 300 | 0.2 | | >300 – 1000 | 0.3 | | >1000 – 3000 | 0.4 | ISO 2768-1 defines four tolerance classes: f (fine),
| Shorter side length range | Tolerance (mm) | |----------------------------|----------------| | ≤ 100 | 0.2 | | >100 – 300 | 0.3 | | >300 – 1000 | 0.4 | | >1000 – 3000 | 0.5 |
October 26, 2023 Subject: Application and Interpretation of ISO 2768-mK
Ensures consistent quality expectations between designers and suppliers globally.
Press fits, slide fits, and bearing journals require tolerances far tighter than the ±0.1 mm to ±0.3 mm provided by the "m" class. These always require explicit limit dimensions or GD&T (Geometric Dimensioning and Tolerancing) callouts. It balances cost, inspectability, and functionality
By avoiding unnecessary precision, manufacturers can use faster, more efficient production methods.
ISO 2768-mK is an international standard that defines general tolerances for machining processes, such as CNC machining . It is typically indicated in the drawing's title block as "General Tolerance: ISO 2768-mK".
While ISO 2768-mK is incredibly versatile, it is not a silver bullet. You should bypass general tolerances in the following scenarios:
Perpendicularity limits depend entirely on the length of the shorter side forming the 90∘90 raised to the composed with power Nominal Length Range (mm) Perpendicularity Tolerance (mm) for Class "k" Over 100 to 300 Over 300 to 1000 Over 1000 to 3000 3. Symmetry
ISO 2768-1 defines four tolerance classes: f (fine), m (medium), c (coarse), and v (very coarse). The "m" designation means your design will follow medium tolerance limits.
is the go-to default for general machined parts in most workshops. It balances cost, inspectability, and functionality. Always verify that your feature tolerances (especially form) are adequate for assembly – if not, add explicit GD&T.
The standard represents the "Medium" standard of modern manufacturing. It balances manufacturing cost with functional reliability. By applying this standard, companies reduce drawing clutter, minimize misinterpretation, and ensure that parts are manufactured to a consistent, acceptable quality level.
If you are working with a (like plastics) that might require different tolerance considerations.
: For class K, the general tolerance for symmetry is for all nominal lengths up to
The lowercase letter represents the tolerance class for linear dimensions (lengths, radii, diameters) and angular dimensions. ISO 2768-1 defines four accuracy classes: f – Fine m – Medium c – Coarse v – Very Coarse
Set at 0.6 mm for features up to 300 mm, increasing to 1.0 mm for larger features. Circular Run-out: Generally specified as 0.2 mm. Why Use ISO 2768-mK?
For linear measurements like external/internal sizes, heights, and distances. Nominal Range (mm) Tolerance (± mm) 120 to 400 400 to 1000 Geometric Tolerances (Class K)
| Nominal Length Range | Tolerance (mm) | |----------------------|----------------| | ≤ 10 | 0.02 | | >10 – 30 | 0.05 | | >30 – 100 | 0.1 | | >100 – 300 | 0.2 | | >300 – 1000 | 0.3 | | >1000 – 3000 | 0.4 |
| Shorter side length range | Tolerance (mm) | |----------------------------|----------------| | ≤ 100 | 0.2 | | >100 – 300 | 0.3 | | >300 – 1000 | 0.4 | | >1000 – 3000 | 0.5 |
October 26, 2023 Subject: Application and Interpretation of ISO 2768-mK
Ensures consistent quality expectations between designers and suppliers globally.
Press fits, slide fits, and bearing journals require tolerances far tighter than the ±0.1 mm to ±0.3 mm provided by the "m" class. These always require explicit limit dimensions or GD&T (Geometric Dimensioning and Tolerancing) callouts.
By avoiding unnecessary precision, manufacturers can use faster, more efficient production methods.
ISO 2768-mK is an international standard that defines general tolerances for machining processes, such as CNC machining . It is typically indicated in the drawing's title block as "General Tolerance: ISO 2768-mK".
While ISO 2768-mK is incredibly versatile, it is not a silver bullet. You should bypass general tolerances in the following scenarios:
Perpendicularity limits depend entirely on the length of the shorter side forming the 90∘90 raised to the composed with power Nominal Length Range (mm) Perpendicularity Tolerance (mm) for Class "k" Over 100 to 300 Over 300 to 1000 Over 1000 to 3000 3. Symmetry