Iso 2768-mh Tolerance Chart ⭐ No Password
| Shorter Side Length (mm) | Tolerance (mm) | |--------------------------|----------------| | ≤ 100 | 0.2 | | >100 to 300 | 0.3 | | >300 to 1000 | 0.4 | | >1000 to 3000 | 0.5 |
The ISO 2768-mH callout is a common engineering standard that sets "medium" general tolerances for a part's size and geometry. Instead of labeling every single dimension with a plus-minus value, adding "ISO 2768-mH" to your drawing's title block establishes a global default for all untoleranced features.
m: Stands for Medium precision for linear and angular dimensions (Part 1).
H: Stands for High precision for geometrical tolerances like flatness and perpendicularity (Part 2). ISO 2768-1: Linear & Angular (Class 'm')
These values apply to lengths, diameters, and angles that don't have an individual tolerance. Linear Dimensions (in mm) For lengths, widths, and diameters: 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 External Radii & Chamfer Heights Used for rounded edges or beveled corners: Nominal Size Range (mm) Tolerance (± mm) over 3 to 6 Angular Dimensions Applies to the shorter leg of the angle: Nominal Length Range (mm) Tolerance (±) over 10 to 50 over 50 to 120 ISO 2768-2: Geometrical Tolerances (Class 'H')
The "H" class defines how flat, straight, or square a part must be. Feature Type Basic Range (mm) Tolerance (mm) Flatness & Straightness over 10 to 30 over 30 to 100 Perpendicularity Symmetry Circular Run-out All ranges When to Use ISO 2768-mH
Cost Efficiency: Use these general tolerances for non-critical features to avoid over-engineering and high machining costs.
Simplicity: It keeps technical drawings clean and easy to read.
Note: If a feature is critical for function—like a bearing fit or a sealing surface—you should override this by adding a specific tolerance (e.g., ISO 286) directly to that dimension. General Tolerance - ISO 2768 1 & 2 - ZEISS Quality Forum iso 2768-mh tolerance chart
Here is the content for an ISO 2768-mh tolerance chart, including general tolerance values for linear dimensions, external radii & chamfers, and angular dimensions.
This content is ready to be used in a technical document, blog post, or engineering reference guide.
Broken edges: Unless specified, external broken edges (chamfers/radii) follow linear tolerance class m: ±0.1 to ±2.0 depending on size.
Would you like this content as a printable PDF-ready table or a markdown file for your documentation?
The ISO 2768-mH tolerance chart is an essential standard in mechanical engineering used to simplify technical drawings by providing default tolerances for features that do not have individually specified limits. By referencing "ISO 2768-mH," designers ensure that parts remain functional and manufacturable without the clutter of excessive dimensioning. What Does "mH" Mean?
The designation is composed of two parts from the ISO 2768 standard: Standard Tolerances in Manufacturing: ISO 2768 & ISO 286
The ISO 2768-mh standard is a specific designation within the international manufacturing framework used to simplify technical drawings by providing general tolerances for parts produced by machining or metal removal .
When a drawing specifies "ISO 2768-mh," it refers to two distinct parts of the standard: | Shorter Side Length (mm) | Tolerance (mm)
m (Part 1): Medium tolerance class for linear and angular dimensions .
h (Part 2): High tolerance class for geometrical characteristics (form and orientation) . ISO 2768-1: Linear Dimensions (Class m)
The "m" (medium) class is the most common standard for general CNC machining . It provides acceptable variance for lengths, radii, and diameters based on the nominal size of the feature . Nominal Size Range (mm) Tolerance (± mm) for Class m Over 3 to 6 Over 6 to 30 Over 30 to 120 Over 120 to 400 Over 400 to 1000 Over 1000 to 2000 ISO 2768-2: Geometrical Tolerances (Class h)
The "h" class defines the permissible deviations for the shape and orientation of a part, such as how flat a surface must be or how perpendicular two edges are .
Straightness and Flatness: For a length up to 10mm, class h allows a tolerance of 0.02mm. For lengths over 1000mm, it allows up to 0.5mm .
Perpendicularity: Based on the length of the shorter side. For sides up to 100mm, class h allows 0.2mm variance .
Symmetry: Limits the deviation of two features from a common center line. For lengths up to 100mm, the tolerance is 0.5mm . Why Use ISO 2768-mh?
Simplified Drawings: Instead of labeling every single dimension with a tolerance, designers can simply reference "ISO 2768-mh" in the title block . Broken edges : Unless specified, external broken edges
Cost Efficiency: Using general tolerances ensures that parts aren't over-engineered with unnecessarily tight (and expensive) limits where they aren't needed .
Consistency: It provides a universal language for manufacturers and clients globally, reducing the risk of misinterpretation .
For more complex parts, you can explore the ISO 2768-1 Full Documentation or technical guides from manufacturers like Fictiv and 3ERP for detailed application in CNC machining.
Are you looking to apply these tolerances to a specific material like aluminum or plastic, which might require different considerations? General Tolerance - ISO 2768 1 & 2 - ZEISS Quality Forum
For your workshop wall or CAD template, condense the ISO 2768-mh tolerance chart into this quick-reference table:
| 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° |
| Nominal Size Range (mm) | Tolerance (mm) | |------------------------|----------------| | 0.5 up to 3 | ±0.2 | | >3 up to 6 | ±0.5 | | >6 up to 30 | ±1.0 | | >30 up to 120 | ±2.0 | | >120 up to 400 | ±4.0 |
| 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) |
Practical Example: If you design a shaft with a length of 50mm and do not write a tolerance, ISO 2768-mh applies. Looking at the chart, 50mm falls into the ">30 up to 120" row. Therefore, the acceptable length is 50mm ±0.3mm (49.7mm to 50.3mm).
| 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 |