Analysis of defects and all causes of stamping die process!


Stamping dies are a special process equipment for processing materials into parts (or semi-finished products) in stamping processing.
Classification according to the nature of the process: punching die, bending die, deep drawing die, forming die, etc.
Classification according to the degree of process combination: single process die, compound die, progressive die.

a) Forming die  b) Deep drawing die   c) Flanging die    d) Expanding die

The three elements of stamping production: reasonable stamping process, advanced die, and efficient stamping equipment
Common defects and causes of stamping
1. Falling material, punching, trimming
Defects: excessive burr, deformation, surface scratches, size discrepancies, less holes, etc.
(1) Excessive burr → Excessive or small clearance of cam and concave die; wear of edge; poor guiding accuracy; different location of cam and concave die, etc.
(2) Deformation → hole distance is too small; the press plate and concave die surface are not well matched; gap is too large, etc.
(3) Surface scratching → operation with dragging, pulling, etc.; plate material is scratched in the shearing process, etc.
(4) Size does not match → the feeding is not in place; the positioning device is damaged or loose, position tampering, etc.
(5) Less hole → punch broken; punch length is not enough, etc.

Defective position of drop, punch and trim products easily


Defect-prone location of drawn products

3. Flanging
Defect: Flanged edge is not vertical, flanged edge height is not consistent, flanged edge is stretched, flanged edge is cracked, etc.
(1)Flanging is not vertical → the gap between the convex and concave die is too large.
(2) Flanging height inconsistency → uneven clearance of convex and concave die; inaccurate positioning; inaccurate size of dropped parts.
(3) Flanged edge pulling → scarred edge; impurities on the surface of the part; too low hardness of the edge.
(4) Flanged edge cracking → large burr when trimming; too small gap between convex and concave die; abrupt change in shape at flanged edge.

Flanged products are prone to defects location

4. Bending
Defects: bending angle failure, bending edge rupture, bending R angle at the step, etc.
(1) bending angle failure → the gap between the convex and concave die is too large, the convex and concave die with the angle does not match the thickness of the plate material.
(2) Bending edge rupture → too small convex and concave die clearance; bending angle is too small; punching force is too large and too fast; plate material is hard.
(3) Bending R angle with steps → convex and concave die bending angle is too large; external R angle is too large; bending force is too small.