Concentricity is the term used to describe the uniformity of shape of a round profile during rotation. For manufacturing processes and workpieces that involve rotation, smooth concentricity is usually a prerequisite for functional efficiency and quality assurance. For this reason, the rotational tolerance is also precisely defined as a running tolerance within the framework of the standards on form and position tolerances. Thus, for radial runout, the runout deviation must not exceed the tolerance value for one revolution around the reference axis. For axial axial runout, the same applies to the tolerance value of the axial runout deviation. In the case of total radial or axial runout, again in the case of multiple revolutions about the reference axis and simultaneous radial displacement, the radial or axial runout tolerance values must not be exceeded. A runout test can be performed with a runout tester, but other measuring methods are also available.
The runout tester is used to check rotationally symmetrical objects.