Bending aluminum is a common but precise process in metal processing. Its success depends on material characteristics, tool selection and operation skills. This article integrates industry standard methods and practical experience to systematically analyze 6 mainstream bending technologies and their applicable scenarios.
I. Key preparations before bending
1. Material property analysis
- Alloy selection: Soft aluminum alloys such as 3003 and 5052 are most suitable for cold bending (elongation ≥10%), and hard alloys such as 6061-T6 need to be heated to 200-400°C to reduce the risk of cracking
- Thickness matching: manual tools are recommended to be ≤3mm, and hydraulic bending machines can handle ≤6mm plates
- Springback compensation: reserve 1-5° excessive bending angle (adjusted according to alloy hardness)
2. Tool calibration
- When using a V-shaped opening bending die, the opening width should be 6-8 times the plate thickness (for example: 18-24mm die for 3mm plate)
- The wooden or polyurethane mold needs to be wrapped with flannel on the surface to prevent scratching the anodized layer
II. Detailed explanation of 6 mainstream bending methods
1. Manual bending (suitable for small batch/DIY projects)
- Steps:
① Mark the bending line with a ruler and fix wooden boards on both sides as guides
② Wear anti-cut gloves and slowly apply pressure along the fold line to an angle of 30°
③ Use a rubber hammer to knock on the fold to eliminate stress concentration
- Accuracy control: ±2° (need to be calibrated with an angle measuring instrument)
2. Press brake operation (industrial-grade accuracy)
- Parameter setting:
- Pressure calculation: P=(650×S²×L)/V, where S=plate thickness (mm), L=length (m), V=die opening
- Stroke control: first perform a 5% stroke trial bend to confirm that there is no positioning offset
- Case data: 1.5mm 5052 aluminum plate, 90° bend, rebound compensation 2°, actual forming 88°
3. Rolling forming (arc/cylindrical parts)
- Use a three-roller plate rolling machine and adjust the upper roller pressure = 0.8×plate thickness
- Perform 3-4 incremental bends, increasing the curvature by 15-20° each time
4. Heating-assisted bending (hard alloy)
- Use a propane torch to heat evenly to 260-320°C (surface oxide film begins to turn gray)
- Heating zone width = 5×plate thickness, water quench immediately after bending to prevent over-softening
5. Hydraulic compression molding (complex geometry)
- Mold gap is set to plate thickness + 0.1mm, holding time ≥ 30 seconds
- 6061-T6 plate needs to be cooled to below 50°C in the mold for demolding
6. Innovative method: water jet guided bending
- Use high-pressure water jet to cut a guide groove with a depth of 30% at the fold line
- Reduce bending torque by 60%, especially suitable for ≥ 8mm thick plate processing
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III. Quality control and defect repair
1. Common defect treatment
- Edge cracking: Use a mold with an R angle ≥ 2 times the plate thickness, or annealing treatment
- Orange peel phenomenon: Check the cleanliness of the mold, and use graphite emulsion (friction coefficient ≤ 0.15) as the lubricant
- Angle deviation: Use laser projector for real-time monitoring and dynamic pressure adjustment
2. Surface protection solution
- Apply PET protective film (temperature resistance 150°C) before bending
- Spray 5% nitric acid solution to remove the oxide layer after bending
IV. Equipment selection suggestions (based on production requirements)
| Personal DIY | Manual bending pliers + wooden mold | $50-200 | ±5° |
| Small studio | 10-ton hydraulic bending machine | $1,500-5K | ±1° |
| Mass production | CNC servo bending center | $50K-200K | ±0.5° |
| Special shape | 3D water jet cutting + rolling machine | $300K+ | ±0.2° |