01Internal radius
Use an internal fillet radius equal to or greater than the wall thickness and adjust it to the material and tooling. Some alloys and conditions require larger radii; use standard radii whenever possible.
Why it matters
When bending, the outer face of the sheet metal stretches. A radius too tight for the alloy and its condition can cause cracks or variations in the final angle.
How to apply it
The r ≥ t ratio is an initial reference for ductile materials. Confirm the radius with the material, thickness, and available tools. Keep equal radii in bends where possible to simplify manufacturing.
What to check
It is not a guarantee of crack absence. The material condition and rolling direction also influence the result. If the radius conditions a fit, dimension it on the drawing to validate the outcome.





