PMMI Mechanical Drives Practice Test

The amount that is bought is described by a nominal size. In practice, key stock is designated by this named size (like a standard width), but the actual material is produced and sold with a precise tolerance around that size. This means the real dimensions can vary slightly within a controlled range, ensuring the stock will fit properly into keyways and be interchangeable with other lots. The nominal size serves as the standard reference, while the tolerance handles the inevitable manufacturing variation.