Gb/t 139 14-2002 Dimensional Tolerance of Stamping Parts stipulates the dimensional tolerance of stamping parts. According to the flat stamping parts and forming stamping parts, the dimensional tolerances are specified respectively. On the one hand, the dimensional tolerance of stamping parts is related to the size and thickness of stamping parts, on the other hand, it is related to the precision grade.

Dimensional tolerance of flat stamping parts: divided into 1 1 grades, represented by st 1 to st 1 1, where st represents the dimensional tolerance of flat stamping parts, and the tolerance grade code is represented by Arabic numerals. The accuracy grade is reduced from st 1 to st 1 1.

Dimensional tolerance of the formed stamping parts: the formed stamping parts are divided into 10 precision grades, which are expressed by ft 1 to ft 10, where ft represents the dimensional tolerance of the formed stamping parts and Arabic numerals represent the tolerance grades. The accuracy grade is reduced from ft 1 to ft 10.

Limit deviation of stamping parts: the stamping deviation of hole size is 0, and the upper deviation is the lower deviation plus dimensional tolerance; The upper deviation of shaft size is the basic deviation, and the value is 0. The lower deviation is the upper deviation minus the dimensional tolerance. For hole center distance, hole allowance, length and height of bending and drawing, the upper and lower deviation is specified as half of the dimensional tolerance.