Large radius bending

Apart from aesthetic or functional reasons, a larger bend radius might be required to prevent the material from cracking during bending. Large radius bending is also ideal for creating U-profiles in two or three bends.

Check out our radius tools in the web shop with radii of up to 50 mm. The thinner the sheet and the larger the radius, the more springback. Note that this could result in a radius that is larger than the radius of your tool.

The maximum size of the top tool radius (R_max) for bending up to approx. 90° is R_max = 0.7 x V-opening (V) - 2 x material thickness (s)

A safe minimum V-opening for your bottom tool is V = 2.5 x (radius of used bar (R) + material thickness (S)). The V-angle depends on the springback of the part.

The required bending force is also larger and can be determined by calculating a correction factor (C) and multiplying it with the required force for air bending C ≅ (0.6∙V-s) / (0.7∙V-(s+R)). Please contact WILA for further assistance.

If the tip radius of your top tool exceeds the natural inside radius of the material, Multi-Breakage will occur, resulting in a non-circular bend that has a smaller radius in the center of the bend.

Multi-Breakage is a common phenomenon that occurs when bending a large radius. As the punch engages the working material, the center of the working material separates from the punch and forms a radius smaller than the punch tip radius. This can be reduced by opting for a larger die opening.

Springback will always occur but forming larger radii in thinner materials with higher yield strengths will result in a lot of springback. When bending large radii, springback could easily be up to 30°.

With a radius tool you can bend any angle between 0° and 180° in one or more steps, depending on the bending freedom you have.

Larger radii can be bent in steps using regular tooling. This is often referred to as step bending. A larger number of bend steps will result in a smoother angle, but there will also be a larger build-up of tolerances. The distance between bends has to be greater than the minimum flange length that can be bent on the bottom tool.