What does "profile of a surface" refer to in GDandT?

• A. A measurement of the surface texture
• B. A tolerance that controls the contour of a surface
• C. The average deviation from a mean surface
• D. A specification for surface finish requirements

Answer: (B)

The concept of "profile of a surface" in GD&T refers to a tolerance that controls the contour of a surface. This profile tolerance defines how much a surface can deviate from an ideal surface form or shape, ensuring that the actual surface remains within specified boundaries. This is essential for applications where the exact contour is critical for the functionality and fit of parts.

Profile tolerance can apply to either two-dimensional silhouettes (the profile of a line) or three-dimensional surfaces, allowing for flexible design of complex shapes. It specifies the permissible variation in surface geometry and is a powerful tool for controlling both aesthetic and functional aspects of part design, which is why it is the correct answer in this context.

Understanding this concept helps practitioners set clear expectations for manufacturing processes and ensures that parts will fit and function as intended.