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Engineering Reference
ALUMINUM BENDING FORMULA REFERENCE
Reference for estimating minimum bend radii on aluminum tube. Applies to fully tooled radial draw bending with suitable forming lubricant.
Download Reference DocumentBasic Bending Formula
For tube material with elongation values above 9%, use the formula directly:
F = π / (4S)
Here, S is minimum specified elongation. For alloys below 9% elongation, use the bending factor F from the table based on the lowest elongation value per subgroup.
Bending Factors by Alloy
| Tube Alloy & Temper | Factor F | Elongation |
|---|---|---|
| 1060-0, 1060-H112, 1100-0, 3003-0 | .0302 | 26 – 30% |
| 1100-0, 3003-0, 5052-0 | .0393 | 20 – 25% |
| 5052-0, 6061-0, 6061-T4, 6063-0, 6063-T4 | .0491 | 16 – 19% |
| 2219-T31, T35 & T3511; 5083-0; 5086-0; 5454-0; 5456-0; 6066-T4; 2014-T4; 2024-T3 | .0561 | 14 – 15% |
| 7075-0, 5083-H111, 5086-H111, 5454-H111, 5456-H111, 6063-T1, 2024-0, 2014-0, 2014-T4 | .0654 | 12 – 13% |
| 6061-T6, 6063-T6, 1100-H12, 3003-H12, 5052-H32, 3005-H25 | .0785 | 10 – 11% |
| 1100-H14, H16; 3003-H14, H16; 6063-T832; 5052-H34, H36; 3005-H28, H29, H294; 3003-H28, H294 | .0859 | 6 – 9% |
| 1100-H18, 3003-H18, 5052-H38 | .0927 | 2 – 5% |
Minimum Centerline Bend Radii
Based on a fully tooled radial draw bender. Convert fractional dimensions to the nearest ⅛ inch.
Round Tube
R = (D² × F / t) + 0.785D
Square Tube
R = (E² × F / t) + S
- R
- Centerline radius
- D
- Tube outside diameter
- t
- Wall thickness
- F
- Bending factor from the table
- S
- Specified side dimension of square tube
- E
- Equivalent diameter = 4S / 3.14
Limitations & Notes
- Based on fully tooled radial draw bending equipment with suitable forming lubricant properly applied.
- If slight deformation is acceptable in the bending zone, minimum centerline radius can be reduced by ¼ tube diameter when the inside forming mandrel is omitted.
- For press bending with fully supporting wing tooling or compression bending using the follow block method, multiply values by 2.
- Minimum centerline radius must be at least 3 × D. For all other bending methods, multiply values by 2.5 or use no less than 4 × D.