Table of Contents
What's ISO 2768 All About?
Think of ISO 2768 as the international language of manufacturing. It lays out the rules for general geometrical tolerances and permissible deviations.
It covers everything from linear (straight line measurements) to angular (angle measurements) and even geometrical tolerances for features like straightness, flatness, and symmetry.
Linear and Angular Dimensions
Let’s break it down a bit. Linear dimensions are all about measurements in a straight line, while angular dimensions are the angle between two lines or surfaces.
ISO 2768 sets the rules for both, with different tolerance classes (H, K, and L) showing the permissible deviations in mm. These dimensions are essential in ensuring all the parts fit together just right.
| Linear Dimensions | ||||
|---|---|---|---|---|
| Tolerance Class Designation (Description) | f (fine) | m (medium) | c (coarse) | v (very coarse) |
| 0.5 up to 3 | ±0.05 | ±0.1 | ±0.2 | – |
| over 3 up to 6 | ±0.05 | ±0.1 | ±0.3 | ±0.5 |
| over 6 up to 30 | ±0.1 | ±0.2 | ±0.5 | ±1.0 |
| over 30 up to 120 | ±0.15 | ±0.3 | ±0.8 | ±1.5 |
| over 120 up to 400 | ±0.2 | ±0.5 | ±1.2 | ±2.5 |
| over 400 up to 1000 | ±0.3 | ±0.8 | ±2.0 | ±4.0 |
| over 1000 up to 2000 | ±0.5 | ±1.2 | ±3.0 | ±6.0 |
| over 2000 up to 4000 | – | ±2.0 | ±4.0 | ±8.0 |
| Angular Dimensions | ||||
|---|---|---|---|---|
| Tolerance Class Designation (Description) | f (fine) | m (medium) | c (coarse) | v (very coarse) |
| up to 10 | ±1º | ±1º | ±1º30′ | ±3º |
| over 10 up to 50 | ±0º30′ | ±0º30′ | ±1º | ±2º |
| over 50 up to 120 | ±0º20′ | ±0º20′ | ±0º30′ | ±1º |
| over 120 up to 400 | ±0º10′ | ±0º10′ | ±0º15′ | ±0º30′ |
| over 400 | ±0º5′ | ±0º5′ | ±0º10′ | ±0º20′ |
Geometrical Tolerances
Geometrical tolerances are all about controlling the shape and orientation of features on machined components. ISO 2768 also sets the rules for these, including tolerances for straightness, flatness, and symmetry. These tolerances ensure each part keeps its shape and fits perfectly within the assembly.
| General Tolerances on Symmetry | |||
|---|---|---|---|
| Ranges of nominal lengths in mm | Tolerance Class H | Tolerance Class K | Tolerance Class L |
| up to 100 | 0.5 | 0.6 | 0.6 |
| above 100 to 300 | 0.5 | 0.6 | 1.0 |
| above 300 to 1000 | 0.5 | 0.8 | 1.5 |
| above 1000 to 3000 | 0.5 | 1.0 | 2.0 |
Tolerance Classes in ISO 2768
ISO 2768 has four tolerance classes – very fine (v), fine (f), medium (m), and coarse (c). Each class has different permissible deviations for linear and angular dimensions. The tolerance class designation (like ISO 2768 MK) tells you which tolerances apply.
Tolerance Values and Ranges
The tolerance values in ISO 2768 depend on the relevant nominal size. For example, the permissible deviations for linear dimensions in the M class differ for nominal lengths in mm of 0.5 to 3, 3 to 6, and so on. The standard even provides handy tolerance charts to make it easier to figure out these values.
How ISO 2768 Affects CNC Machining
In the world of mechanical engineering, ISO 2768 is super important. It provides a framework for defining and measuring tolerances, ensuring all components meet the required specs. It is crucial when dealing with complex assemblies, where minor deviations can cause big problems.
The Role of ISO 2768 in Mechanical Engineering
In the world of mechanical engineering, ISO 2768 is super important. It provides a framework for defining and measuring tolerances, ensuring all components meet the required specs. It is crucial when dealing with complex assemblies, where minor deviations can cause big problems.
Understanding ISO 2768 is a must for anyone in mechanical engineering or manufacturing. It sets the rules for general tolerances and permissible deviations, helping to ensure consistency and quality in machined components. Whether dealing with linear, angular, or geometrical tolerances for features, ISO 2768 is your go-to guide.
Machining to Tight Tolerances
CNC machining can achieve tight tolerances, but it’s essential to understand the tolerance levels set by ISO 2768.
For example, the standard sets different permissible deviations for external and internal sizes and external radii and chamfer heights.
| External Radii and Chamfer Heights | ||||
|---|---|---|---|---|
| Tolerance Class Designation (Description) | f (fine) | m (medium) | c (coarse) | v (very coarse) |
| 0.5 up to 3 | ±0.2 | ±0.2 | ±0.4 | ±0.4 |
| over 3 up to 6 | ±0.5 | ±0.5 | ±1.0 | ±1.0 |
| over 6 | ±1.0 | ±1.0 | ±2.0 | ±2.0 |
ISO 2768 and Drawing Specifications
Drawing specifications is a critical part of any manufacturing process. They’re like the blueprint for what the final product should look like.
ISO 2768 helps to simplify these drawing indications by providing a set of general tolerances that apply unless otherwise stated. This helps to reduce confusion and ensures that everyone is working from the same page.
ISO 2768 in the Global Manufacturing Scene
ISO 2768 isn’t just a standard; it’s a commitment to quality and consistency in manufacturing from an international organization.
It sets the bar for what’s acceptable regarding permissible deviations in mm, nominal lengths, and general geometrical tolerances. This standard is a cornerstone in industries that need precision, like aerospace, automotive, and medical device manufacturing.
Wrapping Up
ISO 2768 is more than just a set of numbers; it’s a comprehensive guide to ensuring quality and consistency in manufacturing. By understanding and applying this standard, manufacturers can produce high-quality products that meet exact specifications.
Whether you’re a seasoned engineer or a student just starting, understanding ISO 2768 is a crucial part of your journey in manufacturing.
Frequently Asked Questions
The tolerance range in ISO 2768 refers to the allowable variations in dimensions, which correspond to the tolerance class and the nominal size of the dimension.
Tolerance limits are the maximum allowable variations in dimensions, including linear and angular dimensions. The tolerance class in ISO 2768 defines these limits.
The international tolerance standard is a set of guidelines that define allowable variations in dimensions. ISO 2768 is an example of an international tolerance standard.
Geometric tolerances in ISO 2768 are the allowable variations in the shape and orientation of features on a component. The range includes straightness, flatness, and perpendicularity ranges.
ISO 2768 specifies permissible deviations for various features. It defines permissible deviations for linear dimensions, angular dimensions, chamfer heights, and even geometrical shapes and orientations of features.
General geometrical tolerances in ISO 2768 are the allowable variations in the shape and orientation of features on a component. This includes straightness, flatness, symmetry, and even circular runout ranges.
Mechanical tolerances in ISO 2768 are the allowable variations in the dimensions and shape of a mechanical component. These tolerances ensure that the component fits and functions as intended.
ISO 2768 simplifies drawing indications by providing general tolerances that apply unless a different tolerance appears on the drawing. The process helps to reduce confusion and ensures consistency in manufacturing.
ISO 2768 specifies permissible deviations for external radius and chamfer heights, ensuring these features maintain their specified dimensions.
ISO 2768 impacts machining capabilities by defining permissible deviations, which allow for material removal during processes like CNC machining while ensuring the final product meets the specified dimensions.
Individual tolerance indications are specific tolerance values indicated on a drawing. These values override the general tolerances specified by ISO 2768 when present.
ISO 2768 plays a crucial role in international manufacturing by setting the standard for permissible deviations and ensuring consistency and quality in machined components across the globe.
