Bending is a core process in sheet metal forming: the upper die descends, causing the sheet material to undergo plastic deformation between the upper and lower dies to achieve the set angle. Bending quality directly determines the assembly precision and appearance of enclosure-type parts. We utilize 85T CNC bending machines where back gauges and angles are controlled by the CNC system, ensuring high repositioning accuracy and excellent batch consistency.
Process Overview
CNC bending machines use servo motors to drive the back gauge and worktable. In combination with various upper dies (air-bend, gooseneck, round dies, etc.) and lower dies (V-grooves), bends at various angles are completed. During the programming phase, the lower stroke is automatically calculated based on sheet thickness, material, and springback characteristics. After 100% inspection of the first piece using an angle gauge, batch production commences. Pressure and angle data are recorded throughout the process to ensure batch traceability.
Capability Parameters
- Maximum bending length: 2.5 m
- Bending angle tolerance: ±0.5°
- Bending position tolerance: ±0.2 mm
- Minimum bend flange: Approximately 6 times the sheet thickness
- Bendable sheet thickness: 0.5 – 6.0 mm
Technical Highlights
The core challenge in bending is springback control: springback varies with material, sheet thickness, and angle. Our process database includes built-in springback compensation values for common materials, which are corrected with first-article measurements to ensure batch angles remain stable within tolerance. For short-flange bends, we use优力胶 dies or locating fixtures to prevent part movement. For multiple sheet stacks with dense bends, we plan the bending sequence to prevent interference between the part and the machine tool.
Typical Applications
Enclosure housings, electrical cabinet boxes, brackets, and bent forming of stiffeners. Bending is often combined with laser cutting: laser cutting first, followed by CNC bending, which is the standard machining route for the vast majority of sheet metal structural parts.
FAQ
What if my bend angles are off?
We implement three-tier controls: material springback database + first-article 100% inspection + process patrol inspection, ensuring that batch angle deviations outside tolerance do not normally occur. If your drawings have special angle requirements, please submit them during the quotation stage, and we will arrange a process review.
How tight can I get my bend radii?
The minimum bend flange is generally about 6 times the sheet thickness; for example, for a 1.5 mm sheet, the minimum flange is approximately 9 mm. Too-short flanges are prone to slipping and deformation during bending, so it is recommended to refer to our DFA suggestions during the design phase for optimization.
Will bending leave marks on the surface?
For bent appearance parts, we use mirror-finish dies and protective films to effectively suppress press marks. For 304 hairline-finished and anodized appearance parts, we arrange special quality inspections after bending to ensure the appearance meets assembly requirements.
Do you have bending drawings that need evaluation? Please send your files; we will provide a bending process plan and quotation based on material and batch size.