Sheet Metal Bending Angle Design Tips

Sheet Metal Bending Angle Design Tips

Designing sheet metal bends requires careful consideration of material properties, tooling limitations, and manufacturing feasibility. Here are key tips to optimize your bent parts:

1. Bend Radius Selection

Minimum Bend Radius (to avoid cracking):

Soft Materials (Aluminum, Copper): 0.5 × thickness (T)

Mild Steel (Low Carbon): 1 × T

Stainless Steel, Hard Alloys: 1.5–2 × T

Best Practice: Use ≥ material thickness (T) as bend radius unless sharp bends are required.

2. Bend Allowance & Deduction

Bend Allowance (BA) = Length of neutral axis arc

Formula:

K-factor (typically 0.3–0.5) depends on material & tooling.

Bend Deduction (BD) = Total flat length reduction due to bending.

Tip: Use bend tables (from manufacturers) or CAD software (SolidWorks, AutoCAD) for accuracy.

3. Minimum Flange Length

Rule of Thumb: ≥ 4 × material thickness (T) + bend radius (R)

Example: For 1mm steel (R=1mm), min flange = 4×1 + 1 = 5mm.

Avoid Very Short Flanges: Can cause deformation or tool interference.

4. Hole & Slot Placement Near Bends

Distance from Bend Line: ≥ 2.5 × T + R

Example: 2mm sheet (R=2mm) → Keep holes ≥ 7mm from bend.

Slots & Cutouts: Orient parallel to bends to prevent distortion.

5. Avoiding Springback & Overbending

Springback Compensation:

Overbend slightly (e.g., 1–2° extra) to account for material rebound.

Varies by material (stainless steel springs back more than aluminum).

Coining: High-pressure bending reduces springback but requires stronger tooling.

6. Bend Direction & Grain Alignment

Bend Perpendicular to Grain: Reduces cracking risk (especially in anisotropic materials like aluminum).

Avoid Bending Parallel to Grain: Can lead to fractures.

7. Tooling & Machine Considerations

V-Die Width Selection:

Mild Steel: 6–8 × T

Stainless Steel: 8–12 × T

Punch Tip Radius: Should match desired bend radius.

Laser-Cut Reliefs: For tight bends, add relief notches at bend intersections.

8. Common Defects & Fixes

❌ Cracking at Bend → Increase bend radius or anneal material.

❌ Warping/Uneven Bends → Use proper die width & clamping force.

❌ Dimensional Inaccuracy → Compensate for springback in CAD.

9. Design for Manufacturability (DFM) Tips

✔ Standardize Bend Radii across parts to reduce tool changes.

✔ Avoid Complex Multi-Bends in one operation (consider progressive dies).

✔ Add Bend Reliefs (small cuts) at intersecting bends to prevent tearing.