What is tolerance? What are the tolerance standards?

Tolerances nclude dimensional tolerance, shape tolerance, position tolerance, etc.

① Dimensional tolerance. Refers to the amount of change in the allowable size, which is equal to the absolute value of the algebraic difference between the maximum limit size and the minimum limit size.

② From tolerance. Refers to the total amount of change allowed for the form of a single actual element, including six items: straightness, flatness, roundness, cylindricity, line profile, and surface profile.

③ Position tolerance. Refers to the total amount of change allowed for the position of the associated actual element to the reference. It limits the relative positional relationship between two or more points, lines, and surfaces of a part, including eight items: parallelism, verticality, inclination, coaxiality, symmetry, position, circular runout, and total runout. Tolerances indicate the manufacturing accuracy requirements of parts and reflect the difficulty of their processing.