Principles of Structural Design for Sheet Metal Bending Parts

Generally, sheet metal refers to metal materials with uniform thickness. Common sheet metal materials include stainless steel, galvanized steel, tinplate, copper, aluminum, and iron. This article primarily analyzes the basic principles of sheet metal product design.

1. Minimum Bending Radius for Sheet Parts

When bending sheet parts, if the corner radius is too small, the outer surface is prone to cracking. If the corner radius is too large, the precision of the bent part is not easily maintained due to springback. Thus, a minimum bending radius is specified, as seen in Table below.

MaterialMinimum bending radius (R)
Cold rolled sheet, galvanized sheet, galvanized sheetR ≥ 2t
Brass plateR ≥ 1t
Aluminum alloy plateR ≥ 1.2t

2. The height of the straight edge in bending should not be too small; otherwise, it is difficult to form sufficient bending moment to achieve parts with accurate shapes.

The value of h should be no less than R+2t, as shown in below.

3. When punching near a bent edge, the distance L from the edge of the hole to the center of the bending radius R should not be too small to avoid deformation of the hole after bending.

The value of L should be no less than 2t, as presented in Figure below.

4. When a<R, a residual arc remains on side b near the point a after bending. To avoid this residual arc, ensure a≥R.

5. On U-shaped bent parts, it is best to have bend edges of equal length to prevent shifting to one side during bending.

Related reading: V & U-shaped Bend Force Calculator

If not permissible, a process locating hole can be set, as illustrated in Figure 4.1-8.

6. To prevent cracking or distortion during side (trapezoidal) bending.

Design a reserved slot or change the base to a step shape. The slot width K should be no less than 2t, and the slot depth L should be at least t+R+K/2.

7. To prevent wrinkling due to material compression at the corners during bending, design a reserved notch.

For example, the notch design at the corner of the outdoor unit side plate (top and bottom).

8. To prevent wrinkling on the flat sides of a right angle after bending, design a reserved notch.


9. To prevent springback after bending, design a notch.

10. To prevent cracking after punching and subsequent bending, design a notch.

11. To prevent one side from shrinking inward during bending.

This can be resolved by designing a process locating hole, bending both sides simultaneously, or increasing the flange width to address shrinkage issues.

12. Overlapping form when bending into a right angle.

13. Bending of Protrusions

If bent like in Figure a, where the bending line coincides with the step line, cracking and deformation at the root can sometimes occur. Therefore, offset the bending line from the step line as in Figure b, or design a notch as shown in Figures c and d.

14. To prevent deformation of holes on the bending surface due to stress, the edge distance (to the bottom root) should be no less than A≥4.

Don't forget, sharing is caring! : )


Founder of MachineMFG

As the founder of MachineMFG, I have dedicated over a decade of my career to the metalworking industry. My extensive experience has allowed me to become an expert in the fields of sheet metal fabrication, machining, mechanical engineering, and machine tools for metals. I am constantly thinking, reading, and writing about these subjects, constantly striving to stay at the forefront of my field. Let my knowledge and expertise be an asset to your business.

Up Next

Mastering CAD/CAM: Essential Technologies Explained

Basic Concepts of Computer-Aided Design and Computer-Aided Manufacturing Computer-aided design and computer-aided manufacturing (CAD/CAM) is a comprehensive and technically complex system engineering discipline that incorporates diverse fields such as computer [...]

Virtual Manufacturing Explained: Concepts & Principles

Concept of Virtual Manufacturing Virtual Manufacturing (VM) is the fundamental realization of the actual manufacturing process on a computer. It utilizes computer simulation and virtual reality technologies, supported by high-performance [...]

Understanding Flexible Manufacturing Systems: A Guide

A Flexible Manufacturing System (FMS) typically employs principles of systems engineering and group technology. It connects Computer Numerical Control (CNC) machine tools (processing centers), coordinate measuring machines, material transport systems, [...]

Exploring 4 Cutting-Edge Nanofabrication Techniques

Just as manufacturing technology plays a crucial role in various fields today, nanofabrication technology holds a key position in the realms of nanotechnology. Nanofabrication technology encompasses numerous methods including mechanical [...]

Ultra-Precision Machining: Types and Techniques

Ultra-precision machining refers to precision manufacturing processes that achieve extremely high levels of accuracy and surface quality. Its definition is relative, changing with technological advancements. Currently, this technique can achieve [...]

Exploring High-Speed Cutting: Tech Overview & Application

Cutting machining remains the most prominent method of mechanical processing, holding a significant role in mechanical manufacturing. With the advancement of manufacturing technology, cutting machining technology underwent substantial progress towards [...]

Top 7 New Engineering Materials: What You Need to Know

Advanced materials refer to those recently researched or under development that possess exceptional performance and special functionalities. These materials are of paramount significance to the advancement of science and technology, [...]

Metal Expansion Methods: A Comprehensive Guide

Bulge forming is suitable for various types of blanks, such as deep-drawn cups, cut tubes, and rolled conical weldments. Classification by bulge forming medium Bulge forming methods can be categorized [...]
Take your business to the next level
Subscribe to our newsletter
The latest news, articles, and resources, sent to your inbox weekly.
© 2024. All rights reserved.

Contact Us

You will get our reply within 24 hours.