About stamping - History and Operations

Knowledge about Stamping

Stamping (also known as pressing or punching) is the process of placing flat sheet metal in either blank or coil form into a stamping press where a tool and die surface forms the metal into a net shape. Stamping includes a variety of sheet-metal forming manufacturing processes, such as punching using a machine press or stamping press, blanking, embossing, bending, flanging, and coining. This could be a single stage operation where every stroke of the press produces the desired form on the sheet metal part, or could occur through a series of stages. The process is usually carried out on sheet metal, but can also be used on other materials, such as polystyrene.

Stamping is usually done on cold metal sheet.
 

History

Stamped parts were used for mass-produced bicycles in the 1890s. Stamping replaced die forging and machining, resulting in greatly reduced cost. Although not as strong as die forged parts, they were of good enough quality.

Stamped bicycle parts were being imported into the United States from Germany in 1890. U.S. companies then started to have stamping machines custom built by U.S. machine tool makers. Through research and development Western Wheel was able to stamp most bicycle parts.

Several automobile manufacturers adopted stamped parts before Ford Motor Company. Henry Ford resisted the recommendations of his engineers to use stamped parts, but when the company could not satisfy the demand with die forged parts, Ford was forced to use stampings.

Operations

• 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.