Common Shapes

Common Shapes

Overview: The sheet metal process lends itself well to simple shapes that are typically formed using standard tools and processes. Standard shapes are used for adding stiffness to the sheet metal parts and provide support or clearance for mating parts. The types of common shapes that are addressed in this course are: bends, flanges, hems, joggles, and beads.

Bends

Bends are the most common formed features in sheet metal design. They are defined as the uniform straining of material around an axis. Simple bends are typically formed using a brake press and can be formed at any angle as long as the bent material does not interfere with any surrounding material. Complex or multiple bends are formed using a punch and die, where you are forming the material rather than bending it.

Inset Flanges

Inset flanges are used mainly to support mating parts or provide mounting locations. These features are pierced into the sheet and then bent. The inset flange requires more sophisticated tooling than the simple bend but it is still cost effective compared to machining and/or welding.

Hems

Hems are features that modify the edges of sheet metal parts. They are used primarily for stiffening the part but are also useful for creating smooth edges where safety or contact with other parts is an issue. There are three basic shapes of a hemmed edge: J-hem, Teardrop hem, and Curled hem. The J-hem and the Teardrop hem can be bent closed but the Curled hem cannot.

Joggles

Joggles are features that are used for stiffening and to allow clearance for mating parts. The aerospace industry uses these features extensively because of the large number of sheet metal parts assembled to create a smooth contour. These features are usually formed using special joggle dies that stretch the material into shape.