How is circularity of a cylindrical surface inspected?

How is circularity of a cylindrical surface inspected?

• A. Checking the cross-section of the cylindrical surface is exactly circular within the tolerance.
• B. Measuring straightness along the axis of the cylinder.
• C. Verifying the surface texture and finish.
• D. Checking the overall length of the cylindrical feature.

Answer: (A)

Circularity is a form tolerance that controls the roundness of a surface. For a cylindrical surface, this means each cross-section taken in a plane perpendicular to the cylinder’s axis must lie within a true circle of the specified tolerance. In practice, you inspect by examining cross-sections along the length and checking how far the surface deviates from the best-fit circle in each plane, using a roundness-measuring instrument or a coordinate measurement machine. This directly verifies that the cross-sections are round within the tolerance. Other checks don’t test circularity: measuring straightness along the axis assesses how straight the axis itself runs, not the roundness of the cross-sections; verifying surface texture or finish relates to roughness, not the geometric form; and checking the overall length does not address the cross-sectional roundness.

Circularity is a form tolerance that controls the roundness of a surface. For a cylindrical surface, this means each cross-section taken in a plane perpendicular to the cylinder’s axis must lie within a true circle of the specified tolerance. In practice, you inspect by examining cross-sections along the length and checking how far the surface deviates from the best-fit circle in each plane, using a roundness-measuring instrument or a coordinate measurement machine. This directly verifies that the cross-sections are round within the tolerance.

Other checks don’t test circularity: measuring straightness along the axis assesses how straight the axis itself runs, not the roundness of the cross-sections; verifying surface texture or finish relates to roughness, not the geometric form; and checking the overall length does not address the cross-sectional roundness.