Stretch formed parts are typically large and possess large radius bends. The shapes that can be produced vary from a simple curved surface to complex non-uniform cross sections. Stretch forming is capable of shaping parts with very high accuracy and smooth surfaces. Ductile materials are preferable, the most commonly used being aluminum, steel, and titanium. Typical stretch formed parts are large curved panels such as door panels in cars or wing panels on aircraft. Other stretch formed parts can be found in window frames, boat hulls, architectural shapes and enclosures.
In the automotive industry in particular, stretch forming dies are used to shape body panels. The blank is clamped over the die cavity and the punch is brought down to press the work piece. Because the blank is clamped around its edges, the material stretches and thins as it is formed.
In the aerospace industry the process can be slightly different. Instead of using both a punch and die, the material is clamped and stretched over the forming die to produce aircraft skins.
An old craft, a modern process: People