Flanging

(1) The process of forming or folding the edge of sheet metal part, to form an angled edge (often at 90 degrees) to the main sheet metal body.

(2) A bending operation in which a narrow strip at the edge of a sheet is bent up or down along a straight or curved line. It is used for edge strengthening, appearance, rigidity and the removal of sheared edges. A flange is often used as a fastening surface.

Source: The OHIO State University