What Is Metal Stamping
With stamping presses and dies, sheet metal may be cold-formed into a variety of shapes through metal stamping. Flat sheet metal scraps are fed into a sheet metal stamping press where they are commonly referred to as "blanks" and are shaped into the desired shape using a tool and die surface. At manufacturing facilities and metal fabricators that provide stamping services, the material to be stamped will be positioned between die portions. Pressure will shape and shear the material into the appropriate final shape for the product or component.
This page discusses the stages involved in metal stamping. It also discusses the many stamping presses frequently used, the benefits of stamping over other manufacturing techniques, and the various stamping operations and their uses.
FUNDAMENTALS OF METAL STAMPING
A low-cost, high-speed manufacturing process that creates many identical metal components is metal stamping, also known as pressing. In addition to being undertaken in conjunction with other metal-forming operations, stamping operations are suited to both short and long production runs. They may include one or more highly specialized processes or techniques, such as:
The terms "punching" and "blanking" describe the employment of a die to shape the material into particular shapes. When punching, a scrap piece of material is removed when the punch advances into the die. This makes a hole in the workpiece. In contrast, blanking involves removing a workpiece from the primary component and using it as the intended workpiece or empty space.
By pressing the raw blank against a die with the necessary shape or running the material blank through a roller die, embossing produces either a raised or recessed design in sheet metal.
The workpiece is stamped while sandwiched between a die and a punch or press using the bending process known as coining. This movement results in accurate, repeatable bends because the punch point penetrates the metal. In addition to relieving internal tensions in the metal workpiece, deep penetration prevents spring back.
The broad method of shaping metal into desirable shapes, such as L, U, or V-shaped profiles, is called "bending." When metal is bent, plastic deformation takes place that places stress above the yield point but below the tensile strength. Bending revolves around a single axis.
By using dies, presses, or specialized flanging equipment, flanging is the process of adding a flare or flange to a metal object.
In addition to stamping, metal stamping machines may also cast, punch, cut, and shape metal sheets. Stamped components can be produced with high precision and repeatability using machines programmed or controlled by computer numerical control (CNC). Computer-aided design (CAD) and electrical discharge machining (EDM) ensure accuracy. For stamping dies, there are several tooling machines available. Stamping needs are met by progressive, forming, compound, and carbide tooling. Progressive dies can simultaneously create several pieces on a single piece.
VARIOUS STAMPING OPERATIONS
1. PROGRESSIVE DIE-STAMPING
Progressive die stamping uses stamping stations. With progressive stamping dies, a metal coil is fed into a reciprocating stamping press. As the press depresses, the die closes, stamping the metal and creating the part. The metal travels horizontally to the following station as the press rises. As the component is still attached to the metal strip, these movements must be appropriately aligned.
The last station separates the freshly manufactured component from the remaining metal. Long runs benefit greatly from progressive die stamping since the technique is highly repeatable and the dies last a long time before damage. The intended end product shape and design are gradually achieved by performing a different cut, bend, or punch operation on the metal. This is done at each phase of the process. Additionally, there is less waste and the process is streamlined.
2. TRANSFER DIE STAMPING
Similar to progressive die stamping, transfer die stamping involves separating the item from the cylinder early on. It also entails transferring it through another mechanical transport system, such as a conveyor belt, from one stamping station to the next. Larger pieces that need to be transported to multiple presses are typically subject to this process.
3. FOUR-SLIDE STAMPING
Multi-slide or four-slide stamping are other names for four-slide stamping. This method works best when creating intricate components with lots of bends or twists. Instead of one vertical slide, it shapes the workpiece through successive deformations using four sliding tools. Without dies, the workpiece is shaped by two slides, or rams, striking it horizontally. Additionally, more than four moving slides may be used in multi-slide stamping.
Four-slide stamping offers flexibility because various tools can be mounted on each slide. Additionally, it is quickly produced and inexpensive.
4. FINE BLANKING
Fine blanking, also known as fine-edge blanking, is useful for producing edges with high accuracy. Fine blanking procedures are typically performed using a hydraulic press, a mechanical press, or a combination thereof. They include three basic movements:
- Clamps are used to secure the work object.
- Carrying out the blanking process.
- Ejection of the completed component.
Tools and equipment must be constructed for the higher working pressures required by fine blanking presses. These presses operate at higher pressures than traditional stamping operations.
Surface flatness from fine blanking can be higher than that of other stamping techniques. The edges generated avoid fractures produced with traditional tooling. The fine blanking process is a one-step cold extrusion method, which lowers fabrication costs.
VARIOUS STAMPING PRESS TYPES
Mechanical, hydraulic, and mechanical servo technologies make up the three main categories of stamping presses. Presses are typically connected to an automatic feeder, which feeds coils or blank metal sheets through the press.
Mechanical presses use a mechanical flywheel and motor to move and store energy. Depending on the press, the punches range from 5mm to 500mm. Mechanical presses also vary in speed, usually falling between twenty and 1,500 strokes per minute, but they are often faster than hydraulic presses. These presses are available in capacities, from 20 to 6,000 tonnes. They work effectively for fabricating shallower and easier pieces out of sheet metal coils. They are typically employed for large-scale progressive and transfer stamping.
In hydraulic presses, pressurized hydraulic fluid is used to provide pressure to the material. A hydraulic press exerts pressure with increased precision and consistency than a mechanical press. This is because hydraulic pistons move fluid with a force proportional to the piston head diameter. Additionally, they can deliver their entire force at any point during the stroke and have adjustable stroke and speed capabilities. These presses typically range in size from 20 to 10,000 tonnes and have stroke lengths between 10 and 800 millimeters.
Hydraulic presses are typically used for smaller production runs to produce more intricate and deep stampings. Adjustable stroke length and controlled pressure give them more flexibility.
Flywheels are replaced with large-capacity motors in mechanical servo presses. They can produce more intricate stampings faster than hydraulic presses. There are controls and programming options for stroke, slide position and action, and speed. Direct drive systems or link-assisted drive systems power them. These are the most expensive of the three press types listed.
ADVANTAGES AND DISADVANTAGES OF STAMPING
Stamping has a number of advantages over other techniques, including cheaper die prices, lower secondary costs, and a higher degree of automation. Metal stamping dies often have lower production and maintenance costs than other frequently used methods. In comparison to identical procedures used in other metal manufacturing techniques, secondary costs, such as cleaning and plating, are also cheaper.
Stamping equipment is generally simple to automate. Advanced computer control programs can be applied to increase precision, speed up production, and shorten turnaround times. The high degree of automation also drives down labor costs.
Custom metal stamping die production necessitates a protracted pre-production process since dies must be purchased or created. If the design needs to be modified while the product is produced, dies can be challenging to change.
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APPLICATIONS OF METAL STAMPING
Stamping has many uses, particularly when three-dimensional drawings, lettering, or other surface engraving characteristics are involved. Stamping items are often created for businesses in the automobile, lighting, telecommunications, military and defense, aerospace, medical equipment, electronics, and home appliance industries. Since metal stamping is widely used in anything from household appliances to automobiles, the chances are high that you already have a product in your home with parts made through this process.