Bending technology is often associated with various processes and machines employed in sheet metal fabrication. Such machines include both press brakes and panel benders, but press brakes are the most common bending machines employed in various fabrication shops. Bending using a press brake tooling is often accomplished in various steps.
The sheet metal is first held through clamps between a die and a matching punch. The ram of the machine, fixed with a punch, moves downwards thereby forming the desired bend.
Similarly, in panel bending, the metal sheet is positioned and held below the blank holder’s tool which often descends on the metal sheet and clamps it in place. With the workpiece material protruding on one side of the machine the bending blades from above and below move to bend the material.
The following Figure 1, illustrates the bending mechanism.
In folding, the metal sheet is typically positioned and tightly held using a clamping beam tool. During the folding cycle, the beam swings up or down around a pivot point, and the workpiece is folded into the required shape.
The dimensional accuracy achieved by folding is controlled by the metal folding machine – the bending edge is utilized as a reference while the folding angle is controlled by the flange angle of the folding machine. This ensures high precision. Conversely, bending has a lower short edge dimensional accuracy owing to back gauge positioning. In this sense, errors may accumulate on the inner surface since the bending is controlled by the upper die pressing amount with respect to the thickness of the material.
Bending induces surface scratches on the workpiece since the material workpiece often moves relative to the lower die of the machine. This results in the indentation on the material surface. Similarly, a large workpiece may require many turnovers during a complex folding process and this may inevitably induce scratches on the surface of the workpiece. Conversely, folding operations do not induce surface scratches as the material rests on the metal folding machine table and the process is performed at a shorter cycle time and without the need for turnovers. This results in high surface quality.
Metal folding machines often employ all-electric drive build designs which require lower maintenance and not susceptible to environmental factors. This results in high folding accuracy. On the other hand, bending machines are often hydraulically driven, hence requires high-level maintenance and also may be susceptible to environmental factors.
Material type | Malleability |
|---|---|
Aluminium 6061 |
|
Aluminium 5052 |
|
Annealed steel |
|
Brass |
|
Copper |
|
Mild steel |
|
Stainless steel |
|
Process | Material | Thickness | Max. Fold / Bend Length | Max. fold / bend Angle |
|---|---|---|---|---|
Metal Folding | Mild steel | 15mm | 8m | 45 degrees |
Aluminium | 15mm | 8m | 45 degrees | |
| Stainless steel | 10mm | 8m | 45 degrees |
Metal Bending | Mild steel | 6mm | 4m | 90 degrees |
Aluminum | 8mm | 5m | 90 degrees | |
Stainless steel | 4mm | 2m | 90 degrees |
In the metal folding sequence, the tool for the folding beam approaches the contact from the outside of the workpiece and the material often moves at an exact position as per the programmed angle. As such, the reference side of the material is only on the outer surface of the material hence ensuring high precision. The movement of the metal folding machine as per the programmed folding angle ensures extremely high accuracy. The tolerances of the material thickness do not affect the respective bending angle hence no angle measuring instrument is required.
The article provided a comprehensive review of the bending and folding processes that are employed in material fabrication.
A review of the operational techniques shows that Folding Machines are well suited to handling large panels, multiple-setup components and surface-sensitive materials. When the overall weight of the part is taken into consideration, it becomes easier to maneuver and position large panels when a sheet support system and back gauge system are used. Thus, the cost of production can be minimized.
It has also been determined that folding offers outstanding advantages over bending. Due to its machine-controlled folding angle, folding provides high precision and accuracy; thereby, performing well with thicker materials than bending. Compared to the bending operation, folding produces high-quality products that are free of surface scratches.
Omnidex Laser offers a variety of sheet metal folding services. We are equipped with the Amada HFE-M2 1704 press brake metal folding machine to meet and satisfy the needs of various industries.
Omnidex Laser is always excited to work with our customers and to meet each of their project’s requirements and specifications.
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