The definition of a unilateral tolerance is a tolerance which allows variation in only direction away from the nominal size. The tolerance can be either positive or negative. Unilateral tolerances are often used to specify dimensions that require a specific fit with a mating part.

Why do we use unilateral tolerance?

In contrast to bilateral, a unilateral tolerance will allow the deviation to extend from one side of the true profile line or the other. A unilateral tolerance is a type of unequally disposed tolerance and is designated with the letter “U” in a circle in the control frame.

What is unilateral in tolerance?

A unilateral tolerance exists when a target dimension is given along with a tolerance that allows variation to occur in only one direction. This tolerance is. unilateral, because. the size may only. deviate in one direction.