Bending is a cold-forming process that permanently deforms a sheet or flat bar along a straight line to create an edge and an angle, without removing material. Applied to sheet metal, it is the operation that turns a flat part into an angle section, a U-channel, an enclosure or a cover.
Bending is done on a hydraulic or electric CNC press brake. The sheet rests on a V-die and a punch comes down to deform it. In “air” bending, the most common, the angle depends on how deep the punch enters the die; a back gauge positions the sheet accurately. Two phenomena are corrected at programming stage: springback, which opens the angle slightly after release, and the flat pattern (developed length), the length of flat sheet required, which takes account of the stretch of the neutral fibre. The minimum inside radius depends on the material and thickness: hard aluminium and some steels risk cracking if the radius is too small. A flange that is too short, or a hole too close to the bend, distorts or cannot be bent.
The usual sequence is laser cutting of the flat pattern, bending, then welding or assembly. Bending produces the enclosures, covers, housings, cabinets, frames, brackets, slides and angle brackets of light sheet metalwork. It belongs to the sheet metal and cutting capability. The guide to the price of sheet metal bending details the cost factors.
In a quote request. Supply the bent part in 3D (STEP) and, if possible, the flat pattern as a DXF, with the material, the thickness and the inside radius you want. State the angle tolerance: around one degree is common, tighter costs more. Specify whether dimensions are taken on the outer or inner edges, and the number of bends per part, which determines bending time.