Metal Stamping Companies

About Metal Stamping

Metal stamping is a process employed in manufacturing metal parts with a specific design. A metal alloy sheet is used as the stock. This stock is either stamped on a press using dies and punches or drawn into shapes on hydraulic deep drawing machines. Common examples are sheet metal machines, automobile parts, metal components used in audio and video devices, aerosol spray cans, and even military tanks. A household example is the use of sheets of metal to make pots and pans.

Sheet metal can be molded into different pre-determined shapes. The metal must be malleable and needs to flow easily in order to be drawn into shapes. Stamping can be done on metals like Aluminum, Zinc, Steel, Nickel, Bronze, Copper and other alloys. This is a mass production, economical process with low cycle time. Hence, it is widely used in manufacturing large volume products with semi-skilled labor. The process is also called chipless manufacturing.

Metal Stamping Operation

Metal stamping processes use dies and punches to cut the metal into the required shape. The male components are called punches and the female components are called dies. Press machine tools are used in the stamping process. The die, made of hardened steel, has a contour that matches the shape of the finished part and is mounted on the table of the press. The punch, made of hardened tool steel or carbide, also matches the contour of the part but is slightly smaller to allow clearance between the die and the punch. It is mounted in the head or the turret, which moves down and punches the metal. The thickness of the sheet metal does not change during this process.

Design and manufacture of dies and punches is a highly skilled process and master craftsmen use precision jig boring, grinding, EDM, and lapping machines to produce highly accurate dies.

Progressive stamping is used to design complex profiles. In this process, the profile is cut in steps with a series of different sized die and punch combinations. The first punch in the series cuts a smaller profile and the next punch finely polishes the metal to obtain a desired shape. Tumbling process or deburring is used to remove any sharp edges and burrs. All through the process it is important to maintain a minimum wall thickness for the punched hole.

The metal may be plated with palladium, nickel or tin to protect it from oxidization. Plating improves the durability and solderability of the product. For additional shelf life, the sheet metal is also pre-plated before the actual stamping process. The product is then cleaned to dispose of excess oils, grease, films or other materials used during the stamping process. The heating process follows the cleaning process to enhance the toughness of the metal product. In some cases, to ease the stamping process, the sheet metal is subjected to a stress relieving process that removes internal stresses in the sheet and improves its machineablity.

Metal Stamping Techniques

Several metal stamping techniques are extensively used in industries and engineering applications. Deep drawn stamping, Electronic stamping, Four slide stamping, Medical stamping, Progressive die stamping, Short run stamping, sizing, swaging, coining, and cold extrusion are some of the examples of metal stamping techniques. Some of these are discussed below:

• Fine blanking is used when high accuracy is required. It is adopted when metal parts with smooth edges are to be produced. Fine blanking is a cold extrusion process not to be confused with stamping. This process is used to produce final shape parts that do not require subsequent finishing operations. Fine blanking process proves to be a cost effective as it is a single step operation.
• Progressive die stamping is a forming process that uses a series of dies to work simultaneously on the sheet metal. This process used to fabricate small parts at a fast pace. Progressive die stamping combines forming and cutting process, which saves time and money. Die stepping technique is adapted to stamp the sheet metal simultaneously. A series of dies is used to draw the sheet metal and all the dies stamp the sheet metal simultaneously.
• Deep drawing is used when recessed cavities in parts need to be formed. In this process, the sheet metal is subjected to plastic deformation by using a die and a punch. Once the yield point is reached, the metal starts to flow. A series of processes like sizing, blanking, swaging, etc. Factors like ductility of the metal, diameter to height of the component and corner radius play an important role. Using improper metal stock, a low quality dies, or excessive pressure can lead to defects like strains or ruptures that are immediately visible.
• Clips, springs, and special purpose rings are manufactured using either the hot or cold wire drawing technique. The die has a hole of the required wire size and shape. Metal is either drawn through the hole or extruded to form a coil.

After the metal stamping or forming process is over, the parts can be drilled, subjected to EDM processing or assembled in components.

Metals used in stamping processes

A lot of basic and exotic metals can be used for stamping applications because of their malleable and ductile properties. The metal should not be very hard and ideally should have a low coefficient of flow. Some typical metals include:

• Ferrous metals - stainless steel stampings, and other iron-based metals
• Non-ferrous metals - brass stampings, bronze stampings, zinc stampings, and other metals that are not iron-based
• Exotic metals - beryllium copper, beryllium nickel, niobium, tantalum, and titanium stampings
• Precious metals - gold, silver, platinum, which are often used for decorative stampings

Metal Stamping Applications

Metal stamping is used in engineering applications to manufacture three-dimensional parts, lettering, and other surface definition purposes.

There are many products that are used in process engineering applications, automobiles, electrical appliances, manufacturing units, etc. Some products that are manufactured using metal stamping include: base weights, brackets, balance clamps, brake flanges, conveyer flights, washers, bushing seats, engine bases, flywheel shrouds and friction plates.

The industry of metal stamping has grown rapidly and, where possible, has replaced other metal forming processes like die casting, forging and machining for several reasons.

• The primary reason is cost effectiveness in deploying the stamping process. The dies used in metal forging and casting are more expensive than those used in metal stamping.
• The cost of the secondary processes, like cleaning and plating are greatly reduced.
• Highly automated machines are available that can complete the metal stamping process more quickly than comparable processes. Metal stamping machines range from simple manual presses to computerized machines for complicated parts. The speed and efficiency of the machine depends on the advanced features available in the machine.