Minimum Bend Radius Chart

The minimum bend radius is the smallest inside radius you can bend a sheet without cracking. It depends on the material, temper, thickness, and grain direction. Soft materials like annealed aluminum can bend to a radius equal to the material thickness (1T). Harder materials like 6061-T6 aluminum may need 3T to 6T minimum radius.

Sheet metal has a grain direction from the rolling process. Bending across (perpendicular to) the grain allows a tighter bend radius because the material is more ductile in that direction. Bending with (parallel to) the grain requires a larger radius to avoid cracking. When possible, orient your bends across the grain.

Bending tighter than the recommended minimum radius causes the outer surface of the bend to crack. In ductile materials, you may see orange peel texture before cracking. In harder tempers like T6 aluminum, the material can fracture suddenly. Always use at least the minimum radius or consider annealing the bend zone first.

Bend allowance = (pi / 180) x bend angle x (bend radius + K-factor x material thickness). The K-factor typically ranges from 0.33 for air bending to 0.50 for bottoming. Use our Bend Allowance Calculator for automatic flat pattern calculations.

Yes, but 6061-T6 requires a larger bend radius than softer alloys. For thin gauges (0.032" to 0.063"), use a minimum of 2T to 3T radius. For thicker material (0.090" and above), use 4T to 6T. Bending across the grain and using a generous radius significantly reduces cracking risk. For tight bends, consider 5052-H32, which is much more formable.