Is Flatness a Form Tolerance

Flatness is a GD&T form tolerance that is conceptually simple. According to the ASME Y14. 5 standard, it “specifies a tolerance zone defined by two parallel planes within which the surface must lie.”

Is flatness a tolerance?

Flatness is a condition of a specified surface having all elements in one plane. Flatness tolerance provides a tolerance zone of specified and defined by two parallel planes in where the specified surface must lie. Flatness is applied to an individual surface, flatness tolerance does not need to be related to a datum.

How do you determine flatness tolerance?

Flatness is can be measured using a height gauge run across the surface of the part if only the reference feature is held parallel. You are trying making sure that any point along the surface does not go above or below the tolerance zone.