1 Answer
In Geometric Dimensioning and Tolerancing (GD&T), the **unilateral tolerance** symbol is used to specify a tolerance that only applies in one direction from the nominal value, either above or below it, but not both.
This means that the feature’s dimension can vary only in one direction (either plus or minus), unlike bilateral tolerances, where the variation can occur in both directions from the nominal.
For example:
- A dimension of **10 ± 0.2** means the feature can range from 9.8 to 10.2, with the tolerance allowed in both directions.
- A dimension of **10 +0.2/-0** means the feature can be as large as 10.2, but no smaller than 10. This tolerance is only in the positive direction (plus 0.2), not negative.
The unilateral tolerance is often used when there is a preferred direction of variation, such as when a part should only increase or decrease within a specific limit.
In GD&T, the symbol itself looks like this: **±** with a modifier indicating whether it's a unilateral tolerance (like **+** or **-** only).
This means that the feature’s dimension can vary only in one direction (either plus or minus), unlike bilateral tolerances, where the variation can occur in both directions from the nominal.
For example:
- A dimension of **10 ± 0.2** means the feature can range from 9.8 to 10.2, with the tolerance allowed in both directions.
- A dimension of **10 +0.2/-0** means the feature can be as large as 10.2, but no smaller than 10. This tolerance is only in the positive direction (plus 0.2), not negative.
The unilateral tolerance is often used when there is a preferred direction of variation, such as when a part should only increase or decrease within a specific limit.
In GD&T, the symbol itself looks like this: **±** with a modifier indicating whether it's a unilateral tolerance (like **+** or **-** only).