Forming,Drawing and Coining

Forming,Drawing and Coining

plastic molding (112)

Forming is a process that transforms a flat piece of metal into a three-dimensional part without exceeding the plastic flow limits of the metal. It May involve simply turning up one edge of the blank to produce a right angle. Making a “bead” in a flat piece of metal to make it stiffer is forming. About 50 percent of all automotive stamping are formed to some extent. Forming is usually combined with blanking and piercing but it is often a stand- alone operation. A forming Operation adds considerably to the cost of a metal stamping die. Some typical forming applications include radiator tanks, crankcase and transmission filler caps. The applications are numerous.


Drawing is the most difficult of all stamping operations and one of the most expensive in terms of total cost. In drawing, a flat blank is transformed into a cylinder or box shape–there are infinite variations–by forcing the metal beyond its yield point. Usually a double or triple action press or a press with air cushions is required. Applications of drawing include rocker arm covers, valve covers, and crankcase oil pans.


Coining involves striking a blank with great force to reduce its thickness and improve its physical properties. Most often it is a final sizing operation following other processes to uphold critical tolerances. A variant of the process is called swaging and the purpose is to flatten the end of a round rod to produce a flat section of much greater diameter. Coining applications include rod ends and valve lifters. Bending Small parts are formed by bending press. Larger parts May be bent on a press brake. This relatively simple operation. The tolerances are usually generous. Usually bending is combined with other operations. It is one of the more common operations. There are hundreds of applications. For illustrative purposes, consider an auto-motive ash tray which is usually made up of one member bent into a U-shape to which side pieces are attached by tabs or by welding.

Virtually all metals can be and are used in automotive applications. The workhorse is hot rolled steel, pickled and oiled. The runner up is cold rolled steel. Other widely used metals include stainless steel, aluminum and various copper alloys. Even platinum and gold are used; such as platinum catalytic converters and gold contacts in the computer mechanisms of certain luxury cars. There is a strong thrust toward the use of zinc clad steels as a corrosion resistant measure. These present no problems to the light stamping industry. They are quite easy to form. The HSLA (high strength low alloy) steels have had some impact but they present some technological problems. One interesting development is the wider use of dual and triple metals. Typically they consist of a brass or aluminum body to which silver, palladium and even gold are selectively applied, usually as contact materials in automotive electronics. This is a very new area but one which shows much promise.

by Steven,A China plastic injection molding  service supplier

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