Metal stamping is a cold-forming metal fabrication method that uses pre-shaped dies and pressure to shape sheet metal blanks into products and components. Using automated or manual feeders, manufacturers insert metal sheets into the stamping press between the tool and die surface. The press lowers onto the sheet metal, using compressive force to press the material into the die to create the desired shape.
Also known as metal pressing, metal stamping is a highly versatile process that can produce accurate, uniform products quickly and efficiently. The process is used in both large and small scale production runs and is often combined with other metalworking processes such as machining, assembly, and finishing. There are many specialized stamping techniques that can be used to produce specific results, including:
- Punching. Involves using a die and press to create holes through the workpiece.
- Blanking. Punches the workpiece out of the sheet metal blank.
- Embossing. Creates raised or indented words, figures, and designs into the sheet metal.
- Coining. Similar to embossing, but the workpiece is stamped on both sides to create raised or indented words, patterns, and figures.
- Bending. Using a press brake, force is applied to the metal workpiece, which bends at an angle from the original axis to create a V or U shape.
- Flanging. Edges of the workpiece around punched holes are bent at a 90° angle from the sheet, creating a rim around each hole.
Precision metal stamping, also known as progressive metal stamping, is a particular stamping process that uses a series of consecutive dies to produce detailed and complex metal components quickly and affordably. With precision stamping, the workpiece is fed through the press one station at a time. At each stage, the sheet metal is progressively shaped by minor changes to each die in sequence, ultimately producing detailed components with a high degree of accuracy and repeatability. The reliability, speed, and cost-effectiveness of precision metal stamping make it ideal for large-scale production of detailed metal components, where machining time and costs would be prohibitive.
Stamping can be used to shape a wide variety of metals, both ferrous and non-ferrous. The type of metal you choose for your metal stamped components depends greatly on the application for which it is intended, as well as the size, shape, and design of your product.
Ferrous metals, which contain iron, are typically magnetic and tend to be strong and durable. Steel is a well-known ferrous metal that is used in an extensive range of applications. Ferrous metals are valued for their high strength, but their iron content makes them more susceptible to rust and corrosion than non-ferrous materials. Carbon steel is the most commonly used ferrous metal for metal stamping applications due to its extremely high tensile strength.
Non-ferrous metals and alloys do not include iron and are therefore not magnetic. Non-ferrous metals are very popular for a variety of stamped products due to their high ductility and wide range of useful properties. The most commonly used non-ferrous metals for stamping applications include aluminum, tin, copper, brass, bronze, gold, and silver. Aluminum is particularly popular for stamped components and products due to its low cost, lightweight strength, and corrosion resistance.
When selecting the right material for your metal stamping application, it is also important to consider the material composition of the die you will be using. While most dies are composed of tool steel or hardened steel, different workpiece materials or processes may require an alternative die material, such as aluminum or mild steel.
Metal stamping dies, also known as press tools, are the tools used to shape the metal blanks during the stamping process. Die tools with sharp edges used to cut, punch, shear, or blank the sheet metal are called cutting dies. Those that are used to form, bend, or otherwise shape the workpiece without removing material are called forming dies.
Parts of a Die and Their Functions
While dies can come in many shapes, sizes, and configurations, the following die parts are typically included in the mechanism:
- Die Block. The die block is a pre-shaped mold that is cut, drilled, and indented to establish the shape of the product. The press or punch compresses the workpiece into the die block, cutting, punching, or forcing the metal to conform to the desired shape.
- Die Holder. The die holder holds the die block in place on a bolster plate, which is in turn supported by the upper or lower die shoe.
- Punch Plate. The punch plate is the mechanism that holds the punch to the ram or press and moves with the press against the die.
- Punch. The punch is the portion of the die that presses onto the workpiece to punch or compress it into the desired shape.
- Stripper Plate. This is a thin plate that keeps the workpiece from sticking to the punch after each press stroke.
- Guide Pin. Guide pins ensure that the upper and lower parts of the die are cleanly aligned.
- Pressure Plates and Back-Up Plates. A collection of back-up and pressure plates installed around the die help to ensure that the punch pressure is evenly distributed across the workpiece.
Metal stamping presses are engineered with a variety of actuation methods and press designs to facilitate a wide range of manufacturing needs. The main types of stamping presses include single- and double-acting presses, mechanically driven presses, and hydraulically driven presses.
Single-Acting vs. Double-Acting Presses
A single-acting press features a single ram, while the ram of a double-acting press is divided. Single-acting presses perform one task for each cycle. Double-acting presses perform two tasks at once using two rams, one to hold the blank and one to punch or stamp. For both single- and double-acting presses, the ram is attached to the top of the press and generates motion to compress the metal sheet against the die. Before it is fed into the press, the sheet metal for the workpiece is straightened to create a streamlined flow.
Mechanically Driven Presses
Mechanically driven presses are operated using a motor and flywheel mechanism. The flywheel transfers kinetic energy into the press, moving the ram toward the plate in a smooth, regular motion. Mechanical presses are quick and efficient and can be relied upon to produce consistent results in repeated cycles. The speed and accuracy of mechanical presses make them particularly useful for assembly lines and industrial manufacturing.
Hydraulically Driven Presses
Hydraulically driven presses use fluid or gas pressure to transmit force into the press. They press the ram down onto the workpiece using a constant pressure, unlike mechanical presses which show force progression. Hydraulic presses operate more slowly than mechanical presses but provide a high degree of versatility and control when it comes to tonnage, workpiece size, and component complexity. For this reason, hydraulically driven presses are ideal for creating detailed, complex, and unusually shaped components.
Precision metal stamping offers unique advantages for a wide range of industries. It is quick, affordable, and efficient, creating everything from simple components to complex products with an exceptional degree of consistency between parts. At Keats Manufacturing, we are committed to providing superior metal stamped components for every application.
Using state-of-the-art stamping technology, Keats Manufacturing is pleased to provide industry-leading metal stamping services that meet and exceed your expectations. With more than half a century of experience, we remain at the forefront of the metal manufacturing industry by providing exceptional service and superior solutions for every project. To learn more about our metal stamping and other metal fabrication capabilities, contact us today or request a quote for your next project.