Bending

In addition to sheets (or blanks), sections, tubes, and wires need bending to a great variety of shapes. Accuracy in bending operations is improved with proper control of or compensation for spring back. Limits on the extent of bending are imposed by local necking, fracture, or - for aesthetic reasons - by orange-peel formation. Four slide machines are capable of performing several operations on three-dimensional parts at high production rates.

Roll forming allows the mass production of two-dimensional corrugated sheet, architectural sections, and lock-seam and welded tubes. With proper design, close tolerances can be achieved. Such products are in competition with extruded, shape-rolled, and cold-drawn products. Plates and sections are frequently bent in three-roll benders into complete circles. Tube bending presents the chanllenge of preventing collapse of the tube wall; during bending operations. Complex shapes are now bent under computer control.

Bending a sheet along a curved line is known as flanging. Circular or other close-shaped flanges (collars) are mass generated in preparation for joining tubes and fasteners to sheet, like in heat exchangers. Limits are set via fracture in a stretch flange and via buckling in a shrink flange. Related processes are flanging and necking of tubes and cans, as in case of beverage cans.