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Understanding ISO 2768: General Tolerance Standard for CNC Machining
ISO 2768 is an international standard that defines general tolerances for linear and angular dimensions in CNC machining and other manufacturing processes. It ensures that parts manufactured under this standard will fit together properly without requiring individual tolerance specifications for each feature.
When to Use ISO 2768
ISO 2768 is commonly applied when precise dimensions are required but not every tolerance needs to be individually specified. It is suitable for parts that are not highly critical, allowing engineers and manufacturers to save time in drafting while maintaining quality. It is widely used in mechanical engineering, industrial components, and assemblies where standard tolerances are acceptable.
Interpreting ISO 2768
The ISO 2768 standard includes multiple tolerance classes, including:
- f (fine)
- m (medium)
- c (coarse)
- v (very coarse)
Each class defines acceptable deviations for linear and angular dimensions. Engineers interpret these classes based on the functional requirements of the part. For example, a precision shaft may use the fine (f) class, while a non-critical frame component may use coarse (c).
ISO 2768 Tolerance Table
| Dimension Range (mm) | Fine (f) | Medium (m) | Coarse (c) | Very Coarse (v) |
|---|---|---|---|---|
| Up to 3 mm | ±0.1 | ±0.2 | ±0.5 | ±1.0 |
| 3 - 6 mm | ±0.1 | ±0.2 | ±0.5 | ±1.0 |
| 6 - 30 mm | ±0.2 | ±0.3 | ±0.5 | ±1.0 |
| 30 - 120 mm | ±0.3 | ±0.5 | ±1.0 | ±2.0 |
Materials Applicable to ISO 2768
ISO 2768 tolerances can be applied to a wide range of materials, including:
- Metals (steel, aluminum, stainless steel)
- Plastics and polymers
- Composite materials
The key is that the standard provides general tolerance guidelines regardless of the material, making it versatile across different manufacturing processes.
FAQ: ISO 2768
When should I use ISO 2768?
Use ISO 2768 when standard tolerances are sufficient for your parts, reducing the need for individual dimension tolerances and simplifying design documentation.
How do I interpret ISO 2768?
Interpret ISO 2768 by selecting the appropriate tolerance class (f, m, c, v) based on the part's functional requirements, size, and manufacturing method.
What is the ISO standard for CNC machines?
ISO 2768 is a general tolerance standard applied to CNC machining and other manufacturing processes to ensure consistent fit and function of parts without specifying each dimension individually.
What materials can ISO 2768 be applied to?
It can be applied to metals, plastics, and composite materials, making it suitable for a wide range of industrial components.