GDT:Circularity
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| Symbol | Circularity |
|---|---|
| Type | Form |
| Category | Form |
| Standard | ASME Y14.5 |
| Author | Admin |
| Datums | None |
| Modifiers | ST (statistical tolerance, where allowed) |
| Tolerance zone | Two concentric circles separated by the tolerance value (in any cross-section) |
| Image | GDT-Circularity.svg |
| Common mistakes | Adding datum references; applying circularity to a pattern; using prohibited modifiers |
| Related | F4:Circularity Validation |
Summary
Circularity controls the roundness of a sphere or surface of revolution. It limits each cross-section to lie between two concentric circles.
Definition
For any cross-section perpendicular to the axis of a revolved feature, the surface must fall within a pair of concentric circles separated by the tolerance value.
When to use it
Use circularity to control out-of-roundness on shafts, pins, and spherical features without referencing datums.
Examples
Example: Roundness on a shaft
Circularity applied to a shaft cross-section with no datum references.
Example: Roundness on a sphere
Circularity applied to a spherical feature to control out-of-roundness.
Common mistakes
- Adding datum references to a circularity FCF.
- Applying circularity to a pattern.
- Using modifiers other than ST where allowed.