Extrusion bending: How much material is needed?

In today’s FAQ, we discuss: How much material do we need for Extrusion bending?

This is a key question when it comes to planning for curved aluminium component production. Material allowance during bending is a well-defined science, and we will explain exactly how much extra material will be required for your components.


Why do we need extra material?


Two main factors affect the need for extra material in aluminium bending.

Firstly, the process of bending metal is a careful balance of maintaining profile while forming to shape. During this process, the material used will consistently flex, causing a stretching and opposing compression of metal. The result of this process is a loss of the overall length of material, especially in tighter bends.

Secondly, the process of roller bending – our primary bending form – requires a certain amount of material between the end of the section and the first curve, this is usually known as the Grip Length. This length differs depending on the bending process and even the machine used.


Aluminium Extrusion Bending Allowance


Bend Allowance is usually discussed in terms of sheet bending, but in Extrusion bending there are a few key differences.

To calculate the extrusion bending allowance, you need a few properties, these are:

  • Mean Length or centreline length
  • Profile Width
  • Section Type
  • The thickness of the material
  • For tight or complex bends: K-Factor of the bend


By utilising these properticanble to calculate the following general rules:

Profile Width

Extra Material

50mm300 – 500mm
100mm400 – 800mm
150mm1000 – 1200mm
2000mm1200 – 1500mm

These figures relate to symmetrical and solid aluminium extrusions.

Angles and Channels and Asymmetrical profiles introduce complexities to the bending process focused on their tendency to shift the neutral axis.



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