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Defects in stamping parts and preventive measures

January 30, 2024




The position of the blank hole changes during bending.

The position and size of the hole are incorrect (thinning due to bending and tension).

Strictly control the bending radius, bending angle, and material thickness. Trim the neutral layer of the material and ensure that the depth of the convex mold entering the concave mold is appropriately uniform.


Reasons for non concentric holes:

1. Insufficient bending height.

2. Slipping of the blank.

3. Rebound.

4. Fluctuations appear on the curved plane.

1. Ensure that the left and right bending heights are correct.

2. Correct the worn locating pins and plates.

3. Reduce rebound to ensure the parallelism and flatness of the two curved surfaces.

4. Change the process route by first bending and correcting before punching.


The part where the bending curve and the centerline of the two holes are not parallel and the bending height is less than the minimum bending height shows an outward opening shape after bending.

1. When bending, the minimum bending height H should be ensured (H ≥ R+2t t material thickness R bending radius).

2. Change the shape of the processed parts and remove the part smaller than the minimum bending height without affecting their use.


Holes near curved lines are prone to deformation.

1. When designing bent parts, it is necessary to ensure that the distance X from the bent part to the hole edge is greater than a certain value X ≥ (1.5-2.0) t t, which is the thickness of the bent plate material.

2. Design an auxiliary hole in the bending area to absorb bending deformation stress, which can prevent hole deformation near the bending curve. Generally, the plan of bending first and then punching is adopted.