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.

What are form tolerances?

Form tolerance is a basic geometric tolerance that determines the form of the target (part). Characteristics such as straightness, roundness, flatness, and profile can be measured using calipers, micrometers, height gauges, and other simple instruments.

What is a normal flatness tolerance?

The flatness tolerance zone is two parallel planes 0.1 mm apart. The size can never be greater than 31 or less than 29. … Anywhere it between, the flatness tolerance zone is just any two parallel planes anywhere and in any orientation that will contain the entire surface of the part.