How much does sheet metal spring back when bending?
Springback depends mainly on the ratio of bend radius to thickness and on the material. It is small at tight radii and large at generous ones. As a rough guide, allow about 3 percent of the bend angle at R/t below 1, rising to around 11 percent at R/t above 6, then apply a material factor.
What is springback?
Springback is the elastic recovery of the material when the punch load is removed. The outer fibres were stretched beyond their elastic limit but the inner core still recovers elastically, so the part opens up by a few degrees and the radius grows slightly.
- It increases with the R/t ratio, because less of the section is plastically deformed.
- It increases with yield strength and with the amount of cold work in the material.
- It is smaller in coining than in air bending, because coining loads the whole section.
- It is usually larger across the rolling direction than along it.
What springback factors should I expect by material?
The material factor multiplies the geometric estimate. Mild steel is the reference at 1.0, stainless steel and high-strength steel spring back considerably more, and aluminium sits between.
| Material | Factor on the geometric estimate |
|---|---|
| Mild steel | ×1.0 |
| Aluminium | ×1.2 |
| Stainless steel | ×1.5 |
| High-strength steel | ×1.8 |
How is springback compensated in production?
There are three practical routes: overbend and let the part relax back to the target angle, use a die with an adjustable or movable bottom so the effective angle changes, or use a CNC press brake with angle correction and a measured first part.
| Method | How it works | When to use it |
|---|---|---|
| Overbend | Program a larger angle and let the material relax | Simple parts, wide tolerances |
| Adjustable die | Change the die geometry to close the angle | Variable radius and angle, low volume |
| CNC angle correction | Measure the first part and correct the depth | Repeat production where the angle is critical |
| Coining or bottoming | Load the section so recovery is small | Tight angles with dedicated tooling |
Related technical pages
Springback guide
Why it happens, how it is measured, and how to allow for it.
Bend allowance calculator
Correct the flat pattern once the final radius and angle are known.
Radius dies
Dies for large-radius bends, where springback is largest.
Custom tooling
Profiles made to suit a specific part, radius and material.
Next step
Tell us the material grade, thickness and target angle and we will recommend the tooling and a starting correction.
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