The Basics of Sheet Metal Bending

Whether it is structural or decorative, sheet metal bending is a common process in the manufacturing industry. It is used for ductwork, architectural components, and machine parts. It is important to understand the elastic deformation of metal, as well as the effects of springback on the bending process. There are several types of sheet metal bending, and the best material for the task will depend on the application. The material needs to be malleable and not brittle. For more information on Bending Machines, go to Cotswold Machinery

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To avoid bulging at the bend, relief cuts are often used. The spacing of the holes and bends must be equal to the thickness of the sheet metal and at least twice the radius of the bend. If the edge of the bend is too sharp, the bending process will produce sharp cracks that may propagate. It is also important to keep the bends on a consistent line, as they reduce the number of operations required.

Depending on the material and the bend method, the minimum inside bend radius will vary. For example, mild steel is more ductile than high-tensile steel. The amount of stretch in the sheet metal will also affect the minimum bend radius. For some materials, like aluminium, there is no change in the sheet thickness when bending.

The neutral axis is the point in the bend that is neither inside nor outside the bend. This is usually measured from the inside of the bend. The location of the neutral axis depends on several factors, such as the material, bending methods, and the material’s yield strength. The neutral axis is typically located about 40 percent of the sheet thickness.

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A common rule of thumb when designing bends is to make the intermediate part longer than the flanges. This is to prevent the bending process from producing excess stretching. However, if the radius of the bend is large, this rule may not be applicable. To eliminate this, over-bending is sometimes used. This means that the sheet metal is bent slightly past the angle desired. This will reduce the amount of springback. The calculated increase in bend angle is then accounted for in the allowance.

In addition to the bend angle, springback is also an important factor in sheet metal bending. Springback occurs when the compressive strength of the sheet metal increases to a level greater than the tensile strength. Usually, the amount of springback will increase the bend angle by a few degrees.