At present, precision sheet metal fabrication of unrolling then flattening can reach the accuracy of 0.3 to 0.5 mm. Generally, the bending precision of sheet metal fabrication parts can reach 0.05mm to 0.1mm (CNC machine tool), and the positioning accuracy and repeat positioning accuracy of punching processing are mostly not more than 0.1mm (of course, large sheet metal fabrication products such as parts larger than 1500mm, the accuracy is slightly Larger), so the use of laser / digital punch / water knife cutting, sheet metal parts produced by CNC bending can usually meet the dimensional accuracy requirements.
Tolerance selection for precision sheet metal fabrication processing
It is worth mentioning that how to select the tolerance of sheet metal fabrication parts. At present, the referenced standards in the sheet metal fabrication industry are “Stamping Dimensional Tolerance”, ie GB/T 13914-2013; “Stamping Angle Tolerance”, ie GB/T 13915-2013 and “Stamping Parts' Shape And Position Without Tolerance”, ie GB/T 13916-2013. In the standard GB/T 13914-2013 "Flat Stamping Dimensional Tolerances",it requires the tolerance grades and tolerance values of different sizes of flat parts with basic dimensions of 0 to 6300 mm and sheet thickness of 0 to 6 mm; “Formed Stamping Dimensional Tolerance” specifies the basic dimensions of 0-1000mm and the thickness of the sheet of 0~6mm (three thickness intervals of t≤1mm, 1mm<t≤4mm, t>4mm),as well as the specification of the limit deviation of the stamping parts and the selection of the tolerance level. GB/T 13915-2013 specifies the angular tolerance of stamped parts. GB/T 13916-2013 specifies the shape and position of stamping parts without tolerances.
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