When controlling runout, which specific types are referenced?

• A. Circular or total runout
• B. Relative or absolute runout
• C. Vertical or horizontal runout
• D. Angular or parallel runout

Answer: (A)

When controlling runout in geometric dimensioning and tolerancing (GD&T), the two specific types referenced are circular runout and total runout. Circular runout pertains to how much a surface deviates from being a perfect circle when it is rotated around a central axis. It measures the variation in the radius from a reference point along the surface, ensuring that it is consistent and within specified limits as it rotates.

Total runout, on the other hand, assesses the cumulative variation of the entire surface as it rotates, which includes not only circular variations but also variations in the axial direction. This type indicates how much a part's surface deviates from a perfect cylindrical shape along its entire length.

Both circular runout and total runout are essential for ensuring the functionality of components in assemblies, as they affect how well parts fit together and operate, especially in dynamic applications where rotational movement is involved. Thus, identifying the correct types of runout is critical for maintaining quality and precision in manufacturing processes.