Metal Bending: Processes, Materials, and What Really Matters in Practice
Folding is one of the most commonly used forming processes in sheet metal fabrication. A punch presses the sheet metal into a die, creating a defined angle. That’s the theory. In practice, the choice of material, the bending radius, and design details determine whether a component emerges from the machine flawless or not. BVS Blechtechnik has been using this process for over 30 years, from simple angle profiles to complex sheet metal assemblies for mechanical engineering, electrical engineering, and measurement technology.
What is metal bending?
Folding is a forming process in which sheet metal is permanently shaped into a desired form through the application of controlled force, without heating or cutting the material. It is a cold forming process that, according to DIN 8580, is classified as bending and forms the basis for many industrial bending processes. The result is defined angles, edges, and profiles that, depending on the requirements, are produced as L-, U-, Z-, or other profile shapes.
In practice, this is how it works: A punch—known as the upper die—presses the sheet metal into a die located below it. This die, acting as the lower die, forms the negative mold of the desired angle. The sheet metal is not machined in this process, but rather plastically deformed. Typical products include housings, covers, control cabinet components, brackets, and angle profiles, which are used in virtually every industrial sector: mechanical engineering, electrical engineering, measurement technology, and automotive manufacturing.
Folding and Swivel Bending: What’s the Difference?
Press brake bending is often compared to swivel bending in everyday manufacturing. The main difference lies in the way the tool is guided and, consequently, in the capabilities each process offers.
Swing bending uses a hold-down device and a lower die and typically requires only a single set of dies. This makes it faster and more cost-effective for simpler contours. In press brake bending, on the other hand, different dies are used depending on the component. What may sound like extra work at first glance is actually a decisive advantage: even very tight bends within a single component can be precisely achieved in this way—something that is often not possible with swivel bending. This flexibility is regularly required, especially for more complex parts used in mechanical engineering or equipment manufacturing.
Which metals can be bent, and where the challenges lie
In general, nearly all metallic materials are suitable for bending. At BVS Blechtechnik, the materials processed include aluminum, stainless steel, steel, copper, and brass. The actual limitations of the process lie not in materials that are too soft, but in those that are too hard.
High-strength alloys and spring-hard steels exhibit significant springback after the bending process: After forming, the material tends to return to its original shape. The harder and more springy the material, the more pronounced this effect is, and the more compensation is required in the process design. Brittle alloys can crack or break during bending. Titanium is a particularly extreme example that places significant demands on the tooling, process control, and experience, and is used, among other things, in the field of medical technology. Soft metals such as aluminum or copper, on the other hand, are comparatively less problematic. The real challenge in metal bending begins at the other end of the hardness scale.
Springback and Shrinkage: What to Consider When Cutting
In the end, a sheet metal part is never simply the sum of the dimensions of its sides. Two physical effects play an important role in calculating the cutout and must be taken into account as early as the design phase.
The first is springback. After the punch retracts, the actual bending angle achieved is slightly smaller than the target angle. To compensate for this, the punch is advanced beyond the actual target angle so that the part has the desired shape after springback.
The second effect is what is known as bending shortening. During bending, material is drawn into the radius, causing the finished component to be longer than would be expected from simply adding the leg dimensions. A concrete example: An L-profile with two legs, each 20 mm long, does not result in a blank length of 40 mm, but typically only about 38 mm. This value depends on the punch radius and die and changes accordingly when the tool is changed.
In industrial manufacturing, employees rarely have to deal with this manually anymore. Modern programming software and CNC controls have the necessary corrections built in—partly based on manufacturer specifications and partly on the company’s own test series using different materials and tool combinations. The key requirement always remains the same: The component must be designed correctly from the very beginning.
What Designers Need to Keep in Mind When Bending Metal
Modern press brakes perform calculations quickly, precisely, and consistently. But they do not correct design errors. The most important parameter in designing for bending is the choice of bend radius in relation to material thickness, and this is precisely where a conflict of objectives regularly arises.
Customers want components with as sharp edges as possible and clean transitions. However, if a 2-mm aluminum sheet has been ground with a direction parallel to the future bend edge and is then bent with a radius that is too small, cracks will form on the outer surface. The surface cannot withstand the strain caused by sharp bending. A slightly larger radius reliably prevents this problem in most cases.
This decision must be made during the design phase, not only after the first part has been placed on the machine. Despite all the automation, experienced expertise is indispensable at this stage.
Why Cracks Form at the Bending Edge
When cracks occur along a bend edge, they can generally be attributed to two causes that may reinforce each other. The first is an unfavorable orientation of the blank: If the bend edge runs parallel to the grain direction of the sheet metal, the tendency to crack increases significantly. Rolled sheet metal has a distinct preferred orientation in its microstructure, and it is precisely along this direction that the material is more susceptible to cracking during bending. The second cause is a bending radius that is too small for the specific material and its surface condition.
If you want to mitigate both risks, you have two options: Position the blank so that the bend line runs perpendicular to the cutting direction, or plan for a larger radius from the outset. Both of these decisions are easiest to make during the design phase, before the first blank is loaded onto the machine.
Safety During Setup and the Benefits of Automated Systems
The interaction between the punch and the die is not only a matter of dimensional accuracy but also of workplace safety. The position, mounting orientation, and pressure settings must all match exactly. If too much pressure is applied to the tool during manual setup, it can be damaged or, in the worst case, break.
Modern automated systems largely eliminate this risk. The machine control system recognizes the installed tools, knows their respective pressure limits, and reliably adheres to them. At BVS Blechtechnik, five fully automated press brakes operate with directly connected robotic systems. This not only increases safety but also ensures short setup times and high repeatability across large production runs.
New Technology as a Solution to the Skilled Labor Shortage
Since early 2025, two fully electric EGB-1303ATCe press brakes from AMADA have been part of the machinery fleet at BVS Blechtechnik, marking the first installation of its kind in Germany. The machines are designed from the ground up for ease of use and high process reliability, providing a direct response to the growing shortage of skilled workers in the industry.
The machine is controlled via a tablet and features voice guidance, integrated camera monitoring, and an augmented reality-assisted backgauge. Bending programs are created offline using the VPSS-4ie system and transferred directly to the machine. The machine automatically detects angles and flexibly adjusts to different geometries. This ensures consistently precise bending results, regardless of the operator’s level of experience. This technology is particularly effective for one-off parts, varying product types, and small production runs.
What Makes Metal Bending So Important in Practice
From the outside, metal bending seems unspectacular. But once you understand how much material knowledge, design expertise, and process experience go into every bend angle, you’ll see the finished component in a whole new light. Automation has simplified many aspects of the process: springback is compensated for by software, setup times are minimized, and safety risks are reduced. But making the right decisions regarding radius, grinding direction, and material selection remains a task that requires experience and material knowledge—qualities that no software can replace.
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FAQ
What is the difference between edge folding and bending?
Bending is the general term for all forming processes. Folding is a specific type of bending in which a punch presses the sheet metal into a die, thereby creating a defined angle along a straight line.
How thick can the sheet metal be when it’s being folded?
That depends on the material and the pressing force. At BVS Blechtechnik, sheets several millimeters thick can be precisely folded using up to 130 metric tons of pressing force. The exact limit varies depending on the application.
What is the minimum bending radius that must be observed?
The radius depends on the material and sheet thickness. As a rough rule of thumb, the inside bend radius should be at least 1 to 1.5 times the material thickness—depending on the material and surface condition.
Can all metals be folded?
Most metals, such as steel, stainless steel, aluminum, copper, and brass, are well-suited for this process. There are limitations when it comes to very hard or brittle materials, while soft metals can usually be processed without any problems.
At what quantity does it become worthwhile to use a folding machine?
This process is suitable for individual parts, prototypes, and production runs. Modern CNC press brakes make it possible to produce even small batch sizes cost-effectively thanks to short setup times.
What information do you need to provide a quote?
To review your request, we need your design data, ideally as a 3D model in STEP or STP format. We can also process 3D data in SAT format. Two-dimensional production data can be submitted as a DXF or DWG file. We work with the Creo Direct Modeling and Creo Parametric CAD systems and integrate your data directly into our feasibility analysis. During this process, we review the production data, prepare the 3D model for manufacturing, and plan for reliable implementation.
How early should the manufacturing team be involved?
Ideally, as early as the concept and design phase of your product. Right from the start of the project, we work with you to determine the exact requirements for the sheet metal solution—from form and functionality to protective criteria such as moisture or dust protection. This allows us to ensure feasibility and cost-effectiveness early on, before the design is finalized.
