To manufacture machine parts according to their intended purpose, it is sufficient for them to fall within two acceptable limit values. The difference between these two limit values is called tolerance.

Tolerance is essentially a margin of error. Tolerance is a critical concept, and we can determine the specific intervals and criteria for the parts to be used only by specifying their tolerances. The conditions of tolerances vary for factors such as temperature, friction, lubrication conditions, speed, load, precision, vibration, and more, depending on the place of use.

Tolerances are divided into three categories: dimension, shape, and surface tolerances.