Which term represents a form tolerance that constrains the flatness of a surface?

Which term represents a form tolerance that constrains the flatness of a surface?

• A. Parallelism
• B. Perpendicularity
• C. Flatness
• D. Cylindricity

Answer: (C)

Flatness is a form tolerance that restricts how much a surface can deviate from being a perfect plane. When specified, every point on the surface must lie between two parallel planes separated by the tolerance value, ensuring the surface remains as plane-like as possible. This control is about the intrinsic shape of the surface, not its location or orientation relative to datums. By contrast, parallelism and perpendicularity govern how a surface sits in relation to datum references, and cylindricity controls how close a surface is to an exact cylinder. So the term that directly represents a form tolerance constraining the flatness of a surface is flatness.

Flatness is a form tolerance that restricts how much a surface can deviate from being a perfect plane. When specified, every point on the surface must lie between two parallel planes separated by the tolerance value, ensuring the surface remains as plane-like as possible. This control is about the intrinsic shape of the surface, not its location or orientation relative to datums. By contrast, parallelism and perpendicularity govern how a surface sits in relation to datum references, and cylindricity controls how close a surface is to an exact cylinder. So the term that directly represents a form tolerance constraining the flatness of a surface is flatness.