The following table provides an example of the ISO 2768-MH tolerance chart for angular dimensions:
Below are complete tolerance tables per ISO 2768-1 (m class for linear dimensions) and ISO 2768-2 (H class for geometrical tolerances).
Implementing the ISO 2768-mh standard offers several practical advantages for engineering teams, machine shops, and procurement departments:
The standard is divided into two parts to simplify engineering drawings by removing the need for individual tolerance callouts on every single feature. iso 2768-mh tolerance chart
It avoids unnecessarily tight, costly tolerances.
The suffix suffix letters indicate the exact tolerance classes used:
| Type | Condition | Tolerance | | :--- | :--- | :--- | | Linear (0.5-6mm) | Size | ±0.1mm | | Linear (6-30mm) | Size | ±0.2mm | | Linear (30-120mm) | Size | ±0.3mm | | Linear (120-400mm) | Size | ±0.5mm | | Flatness | Form | 0.2mm per 100mm | | Straightness | Form | 0.2mm per 100mm | | Perpendicularity | Orientation | 0.3mm per 100mm | | Symmetry | Location | 0.5mm | | Circular Runout | Runout | 0.2mm | | Angle (<10mm leg) | Angle | ±1° | The following table provides an example of the
| Nominal Dimension Range (mm) | Tolerance (mm) | Interpretation | | :--- | :--- | :--- | | 0.5 up to 3 | ±0.1 | +/- 0.1mm (100 microns) | | >3 up to 6 | ±0.1 | +/- 0.1mm (100 microns) | | >6 up to 30 | ±0.2 | +/- 0.2mm (200 microns) | | >30 up to 120 | ±0.3 | +/- 0.3mm (300 microns) | | >120 up to 400 | ±0.5 | +/- 0.5mm (500 microns) | | >400 up to 1000 | ±0.8 | +/- 0.8mm (800 microns) | | >1000 up to 2000 | ±1.2 | +/- 1.2mm (1.2mm) | | >2000 up to 4000 | ±2.0 | +/- 2.0mm (2mm) |
In the world of engineering and manufacturing, tolerances play a crucial role in ensuring that parts and components fit together seamlessly. One of the most widely used tolerance standards is the ISO 2768-MH tolerance chart, which provides a set of guidelines for determining the acceptable limits of variation in the dimensions of parts and components. In this article, we will take a closer look at the ISO 2768-MH tolerance chart, its significance, and how to use it effectively.
Because the second letter is "H", the part is subject to strict geometrical controls for features like Straightness, Flatness, Perpendicularity, and Symmetry. Nominal Length Range (mm) Geometric Tolerance (in mm) Up to Over Over Over Over Over The suffix suffix letters indicate the exact tolerance
These tolerances apply to features like fillets and chamfers. Notably, for the medium class, the deviations are the same as the fine (f) class.
(very coarse). The "m" class offers a practical balance of precision and manufacturability for standard machined components. 2. The Second Letter: "H" (Higher Geometric Tolerance)
The standard provides a balanced approach to general, non-critical dimensional and geometric tolerancing. By utilizing the "m" (medium) class for linear dimensions and "H" (high) class for geometrical features, it ensures efficient production in CNC machining and other manufacturing processes.
For angles, the tolerance is based on the length of the shorter side of the angle. Range of Nominal Lengths (mm) Permissible Deviations (m - Medium) ±1∘plus or minus 1 raised to the composed with power Over 10 to 50 Over 50 to 120 Over 120 to 400 Data from standard. 3. ISO 2768-2: Geometrical Tolerance Chart ("H" - High)
The designation indicates a specific combination of general tolerances for a technical drawing. The first lowercase letter ( m ) refers to "medium" tolerances for linear and angular dimensions (Part 1), while the second uppercase letter ( H ) refers to the highest precision class for geometrical features (Part 2). Understanding ISO 2768-mh