6. Technological Requirements For Metal Stamping Parts
6.1 Precision Grade Of Metal Stamping Parts
The general tolerances of the length, width, shape,holes or spacing of holes, the distance between holes and holes, the bending length of forming punching, the diameter of drawing and the diameter of the roll circle and other linear dimensions and bending angles (for metal stamping parts) are as following A, B and C grade. According to the different requirements of metal stamping parts, they can be used individually and mixingly.
6.2 General Tolerances For Metal Stamping Parts
6.2.1 General tolerances for linear dimensions of metal stamping parts are shown in Table 1. The value method and its limit deviation value can be selected according to the bidirectional symmetrical deviation, or the value of one-way deviation. For example, the tolerance limit is 0.2, the limit deviation is acceptable +-0.1, -0.2, +0.2. The limit deviation of general hole distance and margin size can be +- 1/2 of tolerance value.
6.2.2 General tolerance of angle (for metal stamping parts)
126.96.36.199 General tolerances for bending angles of metal stamping parts are shown in Table 2.
188.8.131.52 General tolerances for the angle of metal stamping parts are shown in Table 3.
6.2.3 The general tolerance for the straightness of the bending line of bending metal stamping parts is shown in Table 4.
6.3 The Height Of The Burr For Metal Stamping Parts.
The height of the burr is not more than 10% to 15% of the thickness of the material.
7 Quality Testing For Metal Stamping Parts
7.1 The surface of flat metal stamping parts should be smooth without serious corrosion or defect.
7.2 The direction of the hairlining (drawing) of the flat metal stamping parts should conform to the processing requirements of the next working procedure.
7.3 The length, width, shape, spacing of holes or holes, hole margin, drawing diameter and other linear dimensions of flat metal stamping parts should be in accordance with the requirements of the drawing, and if no special requirement, should be inspected applying to C grade precision grade in Table 1.
7.4 The punching angle of flat metal stamping parts should conform to the requirements of drawings. If no special requirement, should be inspected applying to C grade precision grade in Table 3.
7.5 The bending angle of the forming metal stamping parts should conform to the requirements of the drawings, and if no special requirements, shall be tested according to the C accuracy of Table 2.
7.6 The bending line linearity of the forming metal stamping parts should conform to the requirements of the drawings. If no special requirements, shall be tested according to the B grade accuracy in Table 4.
7.7 Measuring method for metal stamping parts
7.7.1 The general tolerance of 0 to 300mm linear dimension can be checked by 0.02 level vernier caliper.
> 300~1000 general tolerance of linear dimension can be checked by 0.05 level vernier caliper.
> 1000~4000 general tolerance of linear dimension can be checked by centimeter 2 degree tape.
7.7.2 The angle and bending angle of blanking metal stamping parts can be checked by 0~360 degree universal angle ruler.
7.7.3 The forming metal stamping parts and bending line straightness are generally put on the platform and measure the gap with the thickness gauge. The measuring point should not be less than two points, and the maximum error value is the straightness error of the bending line.
8 Safety And Precautions
8.1 Before the punch moves, it must check that the punch is running normally and the die is in good condition.
8.2 The mold for metal stamping parts must be careful and careful when it is installed.
8.3 In metal stamping parts’ processing, it is strictly prohibited to contact the mold processing area with hands. The hands and feet should be well matched, and feet are not allowed to pedal on the pedal for a long time.
8.4 Safety operation rules for punching machine (CNC punching machine) must be strictly implemented during operation.
8.5 After the work (of metal stamping parts) is finished, the motor should be switched off and the power supply cut off, then the machine tool is scrubbed and coated with antirust oil.
8.6 Protective equipment should be worn during operation.
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