01How the process works
The press brake forces the sheet into a V die with a punch. Bend angle depends on punch depth, die opening, material thickness and springback; CNC brakes with angle measurement compensate automatically. Bend sequence determines whether flanges can be formed without collision.
Typical acceptance features are flange lengths, bend angles, hole positions relative to bends and flatness. High strength steels and thick plates risk cracking on the outside of the bend if the bend radius is too small or the bend runs parallel to the rolling direction.
- Blank cutting. Laser, punch or shear to the flat pattern.
- Deburring. Edges cleaned.
- Bending. Sequence of bends on the press brake.
- Joining. Welding, rivets or PEM inserts.
- Inspection. Angles, flanges, hole positions, flatness.
02What typically goes wrong
| Defect | Typical cause | How it is found |
|---|---|---|
| Angle deviation | Springback, tooling, thickness variation | Protractor, angle gauge |
| Flange length error | Flat pattern calculation, back gauge | Calipers, CMM |
| Cracks at bend | Radius too small, grain direction | Visual, PT |
| Tool marks | Die shoulders | Visual |
| Hole distortion near bend | Hole too close to bend line | Visual, gauges |
| Twist | Bend sequence, residual stress | Flatness on surface plate |
03Where an inspector should look
Before production
- Flat pattern and bend allowance
- Minimum bend radius for the material
- First piece approval
During production
- Angle checks per batch
- Back gauge set-up
- Material lot traceability
After production
- Dimensional report
- Surface quality before painting
- Fit check of assemblies
04Standards and references
EN 10025 and EN 10051 (steel plate and sheet), ISO 9013 (thermal cut tolerances), DIN 6935 (bending of flat steel).
Standards are named for orientation. The applicable edition and acceptance criteria are those in your contract and specification.