Fulei Metal Bending Show Time——Bending Loss

Bending Loss: How to Optimize Material Utilization in Sheet Metal Fabrication

In sheet metal fabrication, bending (forming) is a common process, but it inevitably leads to material loss. Waste affects production costs and efficiency, so optimizing the bending process to minimize loss is crucial.

1. What is Bending Loss?

Bending loss refers to the unusable portion of material caused by stretching, springback, and localized deformation during the bending of metal sheets. Key contributors include:

Stretching loss in the bend radius area (material elongation at the bend)
Springback compensation waste (extra material loss due to adjustment for springback)
Tooling dent damage (marks from the press brake die/punch)
Edge deformation (distortion near the bend line affecting further processing)

Typical Bending Loss Examples

Material Thickness (mm)	Bend Angle (°)	Estimated Loss (mm)
1.0	90°	~0.3-0.5
2.0	90°	~0.5-0.8
3.0	90°	~0.8-1.2

2. Main Causes of Bending Loss & Optimization Methods

(1) Springback Loss

📌 Issue: Metal springs back after bending (e.g., a 90° bend may rebound to 92°), requiring rework and wasting material.
✅ Solution:

Use springback compensation (overbending slightly below the target angle).
Select appropriate dies (V-die width ≈6× material thickness reduces springback).

(2) Bend Radius Loss

📌 Issue: Too small a bend radius causes outer stretching cracks or inner wrinkling.
✅ Solution:

Minimum bend radius = 1× thickness (for mild steel/aluminum) or 1.5× thickness (stainless steel).
Use radius dies instead of sharp bends.

(3) Bending Sequence Impact

📌 Issue: Incorrect bending sequence leads to interference, making parts unusable.
✅ Solution:

Bend larger angles first, then smaller ones (avoid collisions).
Simulate sequence in 3D (e.g., AutoForm/SolidWorks).

(4) Edge Deformation Loss

📌 Issue: Bending too close to the edge (<2× thickness) causes distortion.
✅ Solution:

Minimum bend distance = 3× thickness (prevents edge deformation).
Laser cut edges instead of shearing (reduces burrs affecting bend quality).

3. How to Calculate Bending Loss?

Use the BA (Bend Allowance) formula to estimate loss:

$\left( \frac{\pi \times \text{Inside Bend Radius} \times \text{Bend Angle}}{180} \right) + (\text{K-Factor} \times \text{Material Thickness} \times \text{Bend Angle})$

📌 K-Factor (material stretch factor):

Mild steel: K≈0.3 | Stainless steel: K≈0.4 | Aluminum: K≈0.5

👉 Example Calculation
For a 2mm stainless steel sheet, 90° bend, inside radius=2mm:

$\left( \frac{3.14 \times 2 \times 90}{180} \right) + (0.4 \times 2 \times 90) ≈ 3.14 + 72 = 75.14 \, \text{mm}$

This means the bend consumes ~75mm of material length.

4.

1️⃣ Optimize nesting – Share bend lines to reduce separate bends.
2️⃣ Use progressive forming – Multi-step bending minimizes springback.
3️⃣ Precise blank size calculation – Include bend compensation in CAD.
4️⃣ High-precision tooling – Reduces dents and springback.
5️⃣ Automated press brakes + laser measurement – Ensures accurate bends.

5. Future Trends: Innovative Loss-Reduction Tech

🚀 AI springback compensation (dynamic adjustment).
🚀 Real-time 3D scanning (laser-based angle correction).
🚀 Self-learning bending algorithms (robot optimization).

📌 Key Takeaways

Mild steel/aluminum has lower loss (can tolerate minor errors).
Stainless steel/titanium has high springback (requires precision).
Test-bend prototypes before mass production (avoid scrap waste).

💡 “A 10% reduction in bending loss can save thousands annually!”

🔗 Read more about sheet metal optimization tips

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