Stamping is a process that involves placing flat sheet metal, either in a blank or coil shape, into a stamping press. A tool and die surface then shapes the metal into a new form. Stamping includes several sheet-metal forming methods, such as punching with a machine press, blanking, embossing, bending, flanging, and coining. This process may occur in one step, where each press stroke creates the desired shape, or it may require multiple steps.

The process is typically performed on sheet metal but can also be used on materials like polystyrene. Progressive dies are often fed from a steel coil. The coil is unwound, straightened to remove the coilset (the tendency for the material to retain the coil's bend), and then moved by a feeder into the press and die at a set distance. The number of stations in the die depends on the complexity of the part being made.

Stamping is usually done on cold metal sheets. For information about forming hot metal, see "forging."

History

It is believed that the first coins were made by the Lydians in what is now modern-day Turkey around 700 B.C. Until 1550, the hammering method was the main way coins were created. Marx Schwab from Germany developed a new stamping method that used up to 12 men turning a large wheel to press metal into coins. In the 1880s, the stamping process was improved further.

Stamped parts were used to make bicycles in large numbers during the 1880s. Stamping took the place of die forging and machining, which greatly lowered costs. Although stamped parts were not as strong as those made by die forging, they were still of good quality.

Stamped bicycle parts were brought from Germany to the United States in 1890. American companies then had stamping machines built by U.S. tool makers. Through research and development, Western Wheel was able to stamp most bicycle parts.

Several car makers began using stamped parts. Henry Ford did not want to use stamped parts at first, but when his company could not meet demand with die forged parts, Ford had to switch to stamping.

Throughout the history of metal stamping, forging, and deep drawing, presses of all kinds have been essential in metal manufacturing. These processes continue to improve by moving more metal in a single press stroke. Presses and connected automation tools increase production speed, lower labor costs, and improve worker safety.

Operation

• Bending – the material is changed shape by being bent along a straight line.
• Flanging – the material is bent along a curved line.
• Embossing – the material is pushed into a slight dip. Used mainly to add decorative designs. Also related: Repoussé and chasing.
• Blanking – a piece is cut from a sheet of material, usually to create a blank for later steps.
• Coining – a pattern is squeezed into the material. Traditionally used to make coins.
• Drawing – the surface area of a blank is stretched into a different shape through controlled movement of the material. Also related: deep drawing.
• Stretching – the surface area of a blank is increased by pulling it outward, with the edges of the blank not moving inward. Often used to make smooth parts for car bodies.
• Ironing – the material is squeezed and made thinner along a vertical wall. Used for beverage cans and ammunition cases.
• Reducing/Necking – used to slowly decrease the size of the open end of a container or tube.
• Curling – the material is shaped into a tube-like form. Door hinges are a common example.
• Hemming – an edge is folded over itself to increase thickness. The edges of car doors are usually hemmed.

Piercing and cutting can also be done using stamping presses. Progressive stamping combines the above methods using a series of dies arranged in a line. A strip of material passes through each die one step at a time.

Lubricant

The Tribology process creates friction, which needs a lubricant to protect the tool and die surfaces from scratches or galling. The lubricant also helps protect the sheet metal and finished part from surface scraping and makes it easier for the material to flow smoothly, preventing rips, tears, and wrinkles. Many types of lubricants are used for this purpose. These include those based on plant or mineral oils, animal fat or lard, graphite, soap, and acrylic-based dry films. The latest technology in the industry is polymer-based synthetic lubricants, also called oil-free or non-oil lubricants. The term "Water-Based" lubricant refers to a larger group that includes both newer water-based products and more traditional oil or fat-based compounds.

Simulation

Sheet metal forming simulation is a technology that helps predict problems that can happen during the process of shaping sheet metal, such as cracks, wrinkles, springback, and thinning of the material. Also called forming simulation, this technology uses a type of advanced computer analysis to study how materials behave under pressure. It is especially useful in the manufacturing industry, particularly in the automotive industry, where reducing costs, saving time, and making production efficient are important for business success.

A study by the Aberdeen research company in October 2006 found that the most successful manufacturers spend more time using simulation early in their projects, which helps them save time and money later.

Stamping simulation is used when a designer or toolmaker wants to check if a sheet metal part can be made successfully without building a physical tool. This process allows designers to test how a part will be shaped on a computer, which is much less expensive than making a real tool to try it out.

Results from stamping simulations help designers quickly compare different design options to create parts that are easier and cheaper to produce.

Microstamping

Stamping sheet metal parts has usually been studied for large-scale uses, such as in vehicles, airplanes, and packaging. However, as things have become smaller over time, scientists have started researching ways to stamp tiny parts. In the early to mid-2000s, tools called micropunching machines were developed. Later, in the 2010s, researchers at Northwestern University tested a machine called a microbending tool. These tools are being studied as alternatives to other methods like cutting with machines or using chemicals. Examples of uses for microstamping include electrical connectors, tiny mesh grids, switches, parts for electron guns, watch parts, components for small electronic devices, and medical tools. Before this technology can be widely used, challenges like ensuring quality, making it work for large amounts of products, and studying how materials behave under pressure must be solved.

Industry-specific applications

Metal stamping can be used on many types of materials because each material has special qualities that make them useful for different jobs in various industries. This process may involve shaping and working common metals or rare metal mixtures to fit the needs of specific tasks. Some industries use metals like beryllium copper, which can carry electricity or heat well, in areas such as aerospace, electrical systems, and defense. Other industries use strong metals like steel and its mixtures for tasks that need high strength, such as in the automotive industry.

Industries that use metal stamping include: