Common Problems and Solutions in Sheet Metal Bending Processing

Sheet metal bending is a common process in manufacturing, but quality problems often arise during actual operation. This article analyzes three typical problems—deformation, workpiece unevenness and surface wear, and cracks and fissures—and provides corresponding solutions.

I. Deformation Problems

Deformation mainly manifests as deformation at hole positions, deformation near the bending area, and deformation after riveting or riveting. The causes and solutions are as follows:

Possible Causes:

Excessive friction between the die and the workpiece;

Equipment operating speed too high, the deformation speed exceeding the operator's adjustment speed for the workpiece;

Uneven stress on the workpiece surface or inherent unevenness;

Inaccurate hole alignment or improper riveting process.

Solutions:

Increase the pressure of the ejector plate, or process a textured surface on the ejector plate to increase friction and prevent workpiece displacement during bending;

Reduce the equipment operating speed, or increase the operator's workpiece support and adjustment speed;

Readjust the force distribution, expanding the force range on the lower surface and reducing local pressure on the upper surface, or ensure the workpiece is placed flat;

Optimize the riveting process, improve the riveting method, or adjust the hole positioning.

II. Workpiece Unevenness and Surface Wear

This type of problem mainly manifests as uneven workpiece end faces, uneven bottoms of concave parts, and wear on the outer surface after bending.

Possible Causes:

During bending, the outer surface is subjected to tensile contraction, and the inner surface is subjected to compressive extension, resulting in deflection and end face bulging along the bending direction;

Uneven raw material, small contact area of ​​the ejector plate, or lack of an ejector device in the die;

Insufficient punch radius, insufficient bending clearance, or overly smooth raw material surface.

Solutions:

Add a shaping process, applying sufficient pressure through the punch and die, and designing a die radius that matches the outer radius;

Pre-level the material, adding an ejector device or dedicated shaping fixture;

Improve the surface finish of the die, increase the punch radius, and adjust the bending clearance appropriately.

III. Cracks and Fissures

Cracks commonly appear at bending angles or propagate along the grain direction during bending.

Possible Causes:

Insufficient inner bending radius, insufficient material plasticity, or material grain parallel to the bending line;

Special material microstructure, prone to fracture along parallel grain direction.

Solutions:

Increase the punch bending radius, adjust the blanking layout direction, or anneal the material, or select a material with better plasticity;

Rotate the sheet metal perpendicular to the bending direction for cutting, or increase the upper die radius (R angle).

By systematically analyzing the causes and implementing corresponding process countermeasures, the quality of sheet metal bending can be effectively improved, production defects reduced, and product precision and durability ensured. Sheet metal bending requires experience; observe how experienced craftsmen bend sheets and why they do it that way. To learn more about bending machines or bending processes, please contact our JUGAO CNC MACHINE team.