Dimensional tolerance standards for metal stampings
At present, metal stamping parts processing is a commonly used metal processing method in China. During the production process of workpieces, due to the comprehensive influence of various factors such as the processing accuracy of machinery and equipment, mold wear, and processing error, it is difficult to achieve absolutely accurate dimensions of metal stamping parts produced and processed.
Therefore, in order to ensure the availability of the workpiece, the tolerance of metal stamping parts must be controlled to the minimum. So do you know what the tolerance standards for metal stampings are implemented according to?
GB/T13914-2002 Dimensional Tolerance of Stamping Parts specifies the dimensional tolerance of stamping parts. Dimensional tolerances are specified for flat and formed stampings respectively. The dimensional tolerance value of stamping parts is related to the dimensions of stamping parts and plate thickness, on the other hand, it is related to the accuracy level.
Dimensional tolerance of flat stamping parts: it is divided into 11 grades, which are represented by ST1 to ST11. Among them, ST represents the dimensional tolerance of flat stamping parts, and the tolerance grade code is represented by Arabic numerals. The accuracy level decreases from ST1 to ST11.
Dimensional tolerance of formed stampings: the formed stampings are divided into 10 accuracy grades, which are represented by FT1 to FT10, where FT represents the dimensional tolerance of formed stampings, and Arabic numerals represent the tolerance grade. The accuracy level decreases from FT1 to FT10.
Limit deviation of stamping parts: the hole size shall have a press deviation of 0, and the upper deviation shall be the lower deviation plus dimensional tolerance; The upper deviation of shaft size is the basic deviation, the value is 0, and the lower deviation is the upper deviation minus the dimension tolerance. The upper and lower deviations of hole center distance, hole edge distance, length and height of bending and drawing are specified as half of the dimensional tolerance.
Tolerance is the range of dimensional changes. The larger the value, the lower the precision, and the less difficult the machining. The smaller the value, the higher the precision, and the greater the machining difficulty.