Fit

The term fit describes the dimensional relationship between two parts that have the same Nominal dimension but have been produced to tolerances that differ in terms of position and size.

Consequently, the term fit also describes the Tolerance within which the actual dimensions of a hole and Shaft, for example, can vary. The finished part will exhibit either a clearance fit (such as in sliding and guiding applications) or an interference fit, which is also referred to as a press fit (Friction Resistance in the case of shrink joints). If tolerances permit both interference and clearance, the fit is known as a transition fit, which can fall into one group or the other during production.

A distinction is also made between Basic hole and Basic shaft fit systems.