Several Tips for Sheet Metal Bending
1. After bending, there may be metal protrusions on both sides of the bent angle due to material extrusion, resulting in a width larger than the original dimension. The size of the protrusion depends on the material thickness, with thicker materials causing larger protrusions. To avoid this phenomenon, it is recommended to create a half-circle on both sides of the bending line in advance, with a diameter of at least 1.5 times the material thickness. The same method can be applied when designing the reverse fold of the edge material.
2. When bending sheet metal, it is advisable to bend perpendicular to the direction of the metal material fibers. Bending parallel to the fiber direction can easily cause cracks at the bending point, resulting in lower strength and increased risk of fracture.
3. To ensure bending strength, long and narrow bends have lower strength compared to short and wide bends. Therefore, it is preferable to attach the bending line to the longer edge of the sheet metal. For the same functional bend, the original design with the bending line attached to the shorter edge would have lower bending strength, while an improved design with the bending line attached to the longer edge would have higher bending strength.
4. The internal radius (R) of the bend should be equal to or greater than half of the material thickness. If no radius is provided, after multiple stamping operations, the sharp corner will gradually disappear, and a natural radius will form. Afterward, the length of one or both sides of this radius will have a slight increase in length.
5. If there is no specific requirement for a 90-degree angle at the corner of the metal sheet, it is recommended to add an appropriate radius (R). Sharp corners at the edge of the metal sheet can cause injuries due to their sharpness. Additionally, the top of the male die is prone to cracking due to stress concentration, while the top of the female die is prone to fracture. This requires mold repair, leading to production delays. Even if no fracture occurs, over time, wear will occur, forming a radius and causing burrs, resulting in defective products.
6. It is challenging to maintain the straightness of long and narrow sheet metal parts, and they are more prone to deformation under stress. To maintain their strength and straightness, it is recommended to bend them into an L-shape or fold two edges to form an "M" shape. However, it is often not possible to connect the L-shape or "M" shape from end to end due to certain factors. In such cases, adding appropriate ribs can increase their strength.
7. When transitioning between flat surfaces and bending surfaces, narrow holes or edge holes should be recessed after bending to prevent burrs. The width of narrow holes should be equal to or greater than 1.5 times the material thickness. Additionally, when creating the drawings, do not forget to indicate the radius (R). The male and female dies of molds for right angles and acute angles are prone to fracture. Once production is halted, mold repair becomes a loss.
8. Sheet metal bending tolerances are relatively large, especially in multiple bending operations, where the accumulation of tolerances makes it difficult to align hole-to-hole. The more bending operations performed on the sheet metal, the larger the bending tolerance, making it challenging to ensure dimensional accuracy. This is why it is difficult to align screw holes, rivet holes, and self-riveting holes in sheet metal bending.
9. The more bending operations involved in sheet metal bending, the higher the mold cost and the lower the bending accuracy. Therefore, sheet metal design should strive to minimize the number of bending operations. In the provided diagram, the original design required two bending operations, while the improved design only requires one bending operation to simultaneously complete two bends.
