Metal Stamping

What is Metal Stamping?

Stamping is a metalworking process in which flat sheet metal, in either blank or coil form, is placed into a press where a stamping tool forms the metal into a net shape. Typically performed on cold metal sheet, stamping encompasses a variety of forming processes — such as blanking, punching, bending, flanging, embossing, and coining.

Stampings can be produced in a single-stage operation, where every stroke of the press produces the desired sheet metal part, or through a series of stages. Progressive stamping dies are commonly fed from a coil of sheet metal into a press at a predetermined feed length. The number of stations in the die is determined by part complexity and desired shape.

How Does Metal Stamping Work?

Metal stamping can involve a number of operations, performed simultaneously or in varying sequence. Examples include:

Bending - The material is deformed or bent along a straight line.

Flanging - The material is bent along a curved line.

Embossing - The material is stretched into a shallow depression. Used primarily for adding decorative patterns. See also Repoussé and chasing.

Blanking - A piece is cut out of a sheet of the material, usually to make a blank for further processing.

Coining - A pattern is compressed or squeezed into the material. Traditionally used to make coins.

Drawing - The surface area of a blank is stretched into an alternate shape via controlled material flow. See also deep drawing.

Stretching - The surface area of a blank is increased by tension, with no inward movement of the blank edge. Often used to make smooth auto body parts.

Ironing - The material is squeezed and reduced in thickness along a vertical wall. Used for beverage cans and ammunition cartridge cases.

Reducing/Necking - Used to gradually reduce the diameter of the open end of a vessel or tube.

Curling - Deforming material into a tubular profile. Door hinges are a common example.

Hemming - Folding an edge over onto itself to add thickness. The edges of automobile doors are usually hemmed.

Piercing and cutting can also be performed in stamping presses. Progressive stamping is a combination of the above methods done with a set of dies in a row through which a strip of the material passes one step at a time.