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Recommended minimum bend radius for metal bending
Stainless steel and Aluminum


A general guideline, the minimum metal bend radius is approximately equal to the material thickness. The
following tables showing the minimum bend radius allowable in air bending process for aluminum and steel or stainless steel.


Aluminum (5052 or 3003)

Thickness Developed Inside Bend Radius Vee Die Width
0.190
0.203
 1.260
0.160
0.156
 0.984
0.125
0.125
 0.709
0.100
0.109
 0.630
0.090
0.094
 0.554
0.080
0.078
 0.472
0.062
0.047
 0.394
0.050
0.047
0.276
0.040
0.031
 0.236
0.032
0.031
 0.157

Take note : When bending 6061 aluminum, the minimum inside bend radius should be 6X the material thickness, otherwise cracking is likely to occur during bending.


Steel or Stainless Steel

Thickness Developed Inside Bend Radius Vee Die Width
7 GA (0.179)
0.203
 1.260
10 GA (0.134)
0.156
0.984
11 GA (0.119)
0.125
 0.709
12 GA (0.104)
0.109
 0.630
13 GA (0.090)
0.094
 0.554
14 GA (0.074)
0.078
0..472
16 GA (0.059)
0.047
 0.394
18 GA (0.047)
0.047
 0.276
20 GA (0.035)
0.031
0.236
22 GA (0.030)
0.031
 0.157

.The Air Bending Process

Imetal bendingIn air bending process, the tooling only touches the sheet metal along the bend radius and the two drawn radii. The main advantage of the air bending process is that it is versatile and not entirely dependent upon the tooling. The same bend result can be made with several combinations of upper and lower tooling.

The inside bend radius that is developed during the air bending process depends on 3 factors:
1) the width of the vee die,
2) the stiffness of the material, and
3) the radius of the upper tool.

In general, the wider the vee die, the larger the bend radius. The more ductile (easier to bend)
the material, the smaller the resulting bend radius.