What does 'circularity' refer to?
Your interviewer will likely ask you knowledge-based questions to understand how well you are able to explain concepts to others. Be prepared for questions like this one by practicing a few possibilities ahead of time. In this case, circularity refers to a type of geometric dimensioning and tolerancing (GD&T) callout. It describes how close an object's surface is to a true circle. It's also sometimes called roundness. Its value corresponds to the distance between two concentric circles that contain the deviation of a 2D profile or cross section. The three-dimensional version is referred to as cylindricity. GD&T callouts like this are very useful when communicating designs to manufacturers, and knowing them well can help you stand out in a mechanical engineering interview.
"Circularity is a type of GD&T callout. It measures how much a circular profile deviates from a true circle, and is measured on a 2D profile and not a 3D surface. It can be measured via a dial gauge that is set up on a lathe, measuring the total variation that the gauge travels in one rotation. In design, I would use circularity if I was concerned with the overall variation of a specific circular profile, rather than the cylindricity across the entire surface."
