Steel Sheet Metal Bending: Die Selection and Process Optimization 2026
Sheet metal bending is a fundamental fabrication process for creating desired shapes from flat steel stock. Understanding die selection, bend allowance calculations, and process parameters ensures quality parts and efficient production.
Basic Bending Terminology
- Bend angle: The angle formed after bending
- Bend radius: The inner radius of the bend
- Flange: The flat portion extending from the bend
- Bend allowance: The length of the neutral axis in the bent section
- Springback: The elastic recovery after removing the forming force
Common Bending Methods
Air Bending
- Most common and versatile method
- Tooling does not fully enclose the material
- Same die set produces multiple angles
- Requires more tonnage than coining
Bottom Bending (Coining)
- Material fully compressed between punch and die
- Consistent, precise angles
- Higher tooling costs
- Requires more press tonnage
Edge Bending
- Bending along the edge of the flange
- Used for flanging and hemming operations
- Lower force requirements
Die Selection Guidelines
| Material Thickness | Recommended Die Width (V) | Minimum Flange Height |
|---|---|---|
| 0.5-1.5mm | 4-6 times thickness | 3 x die width |
| 1.5-3.0mm | 6-8 times thickness | 4 x die width |
| 3.0-6.0mm | 8-12 times thickness | 5 x die width |
| 6.0-12.0mm | 10-16 times thickness | 6 x die width |
Bend Deduction and Allowance
Calculating Bend Allowance
Bend Allowance (BA) = Angle x (Radius + K-factor x Thickness)
Where K-factor typically ranges from 0.33 to 0.50 depending on material and bend radius.
Springback Compensation
- Add 1-3 degrees per 90 degree bend for low-carbon steel
- Stainless steel requires 3-5 degrees additional
- High-strength steels may require 5-10 degrees
Steel Grade Considerations
| Grade | Formability | Springback | Notes |
|---|---|---|---|
| Mild Steel (DC01) | Excellent | Low | Easiest to bend |
| HSLA (S550MC) | Good | Moderate | May require warmer temps |
| Stainless 304 | Good | High | Compensate for springback |
| Aluminum 6061 | Very Good | Moderate | Springback similar to SS |
Common Defects and Solutions
- Cracking at bend line: Increase bend radius or anneal material
- Twist/distortion: Ensure proper material support
- Inaccurate dimensions: Compensate for springback
- Surface scratches: Use proper lubrication and tooling
Sourcing Bending-Quality Steel
Xi’an Coremetal Steel supplies cold rolled steel sheets and coils suitable for bending applications. Contact Tracy at tracy@coremetalsteel.com or +86 18291910632 for availability and specifications.