Iso 2768-mh Tolerance Chart

Understanding ISO 2768-MH Tolerance Chart: A Comprehensive Guide

| Nominal Angle Range | Tolerance Class 'm' | | :--- | :--- | | Up to 10mm length of shorter side | ±1° | | >10mm up to 50mm | ±0°30' (30 arc minutes) | | >50mm up to 120mm | ±0°20' (20 arc minutes) | | >120mm up to 400mm | ±0°10' (10 arc minutes) | | >400mm | ±0°5' (5 arc minutes) |

ISO 2768‑1 also provides default angular tolerances (e.g., ±1° for coarse grades, ±0.5° for medium — see the standard for exact figures) and for unspecified radii/chamfers. iso 2768-mh tolerance chart

Thus, ISO 2768-mH (often written as mh) means:

Table 1: ISO 2768-m (Medium) Linear Dimensions

| 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) | It should be used judiciously: clearly noted on

12. Conclusion

ISO 2768‑m is a pragmatic choice for default tolerances in many mechanical drawings, balancing manufacturability and reasonable accuracy. It should be used judiciously: clearly noted on drawings, combined with explicit tolerances or GD&T for function-critical features, and aligned with manufacturing and inspection capabilities.

Summary of ISO 2768-mh

| Parameter | Value | |------------------------|----------------------| | Linear tolerance class | m (medium) | | Geometric tolerance class | H (precision) | | Typical application | General machining, turned/milled parts without individual tolerances | | Standard compliance | ISO 2768-1:1989, ISO 2768-2:1989 | Nominal Size Range (mm) Tolerance (± mm) Over

The "m" (medium) class is the most common standard used in CNC machining. It provides a balanced approach between manufacturing cost and part functionality. Nominal Size Range (mm) Tolerance (± mm) 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 Source: ZEISS Quality Forum ISO 2768-2: Geometrical Tolerances (Class H)

Angular tolerances (examples for grade m):