What Is Metal Stamping?
Metal stamping is a long-trusted technique to create customized metal designs. From machine parts to tools and more, stamping has numerous uses across a wide range of industries. For practical, cost-effective parts, stamping could be the solution you need.
About Metal Stamping
Metal stamping is a way to create parts and tools with fewer people and seamless construction. While metal fabricators have multiple options for creating designs brought to them, stamping offers an unparalleled versatility that makes it the first choice for many projects.
Stamping may use tools that cut or shape the metal. Stampers choose different dies to create the desired shapes, either holes or formed parts. Some systems use a series of dies, in a progressive order. Generally, when cutting or shaping, the process happens to cold metal.
While some types of metal shaping use heat, stamping typically forms the metal without heating it, preserving its natural integrity since metals expand when heated and shrink when cooled. The tradeoff of using cold stamping is the increased precision needed to create the desired three-dimensional shapes. Cold metal is not as malleable as hot metal. When heat enters the picture, the metal’s coefficient of friction raises significantly — 40 percent or higher — resulting in a sticky, hard to work with metal. This friction explains why stamping hot metals is difficult and not preferable for many projects.
Industrial stamping requires the use of dies to form the metal into the desired shapes. Precision, skill and engineering govern the creation of these dies, which need regular maintenance to produce the same tools and parts consistently over time.
The dies have two parts — a male and female. These parts sandwich the metal between them as they press together to shape the form desired. Sometimes, the die will have accessories to add on to customize multiple elements. Depending on the function, the die may cut or shape the metal. Progressive systems send metal through multiple presses to cut and form parts of the metal to create the finished product. Complex shapes will require more stops along the progressive die stamping system than those that need cutting or single-step shaping.
Industries That Use Stamping
Everything from the aerospace industry to the military relies on the formation of metal through stamping. These sectors need substantial, well-formed parts that must perform in a variety of environments from the mundane to the extreme.
- Medical: The medical industry requires a large number of metal parts like implants, but because many of the tools used in this sector are so small, the parts need micromachining or microstamping.
- Automotive: Every automobile on the road today has electronic components that require carefully designed connectors, pins, sensors and more. For proper operation, these parts must have a consistent design, and stamping metal is one way to achieve this. Because the safety of those in the vehicle depends on the operation of these components, the stamped parts must be completely trustworthy.
- Aerospace: Even the tiniest of parts on aircraft must have a perfect design to keep the plane aloft. Precise metal stamping to create pieces for airplanes ensures the safety of all aboard.
- Military: The military use highly specialized vehicles not found in civilian life. Stamping metal to create these parts offers a means of large-scale customized production. The safety and success of the troops rely on how well these metal parts function, which is why not every company that offers progressive die stamping can produce them.
- Consumer electronics: Even the tiniest of parts inside computers and other consumer-grade electronics must have consistent designs. To create the consistency required, manufacturers turn to metal stamped components. Because many parts used in electronics may have hazardous elements, companies that produce them should be compliant with the Restriction of Hazardous Substances (RoHS) to protect the environment.
- Many others: Numerous other industries also use the stamping process to create metal tools and parts.
Our company specialty is in microstamping, which produces small, metal pieces that can fit into the palm of your hand. Often, these pieces are components of electronics or tools. The processes of stamping larger pieces of metal and microstamping are similar. To understand both processes, start with filling out your basic knowledge of stamping metal.
To decide whether you need metal stamping for your project, you must understand the stamping process and how it stands apart from other metal fabrication methods. Several situations make stamping a more effective option than fabrication.
- Cost: Generally, the cost for stamping, depending on volume, is lower than fabrication because this method can produce substantial qualities for less.
- Volume: High-volume output makes metal stamping a more viable option than fabrication. Once die manufacturers create the die, they can form hundreds or thousands of metal parts with it.
- Part size: Smaller parts are easier to make through stamping. Most industry professionals refer to printing tiny parts, such as wires and resistors, as microstamping.
- General shape: Parts that require numerous holes or bends may have lower costs and fewer problems if created through stamping.
- Precision: For parts that require exact placement of holes, especially near edges, with little to no variance between pieces, stamping may be a better option because the die can be more accurate in placing such features onto a part than a fabricator.
- Downstream control: Progressive die stamping allows for more control over added changes to the part down the line, for more control throughout the creation process.
Sheet Metal Stamping
To change a piece of sheet metal into a tool or other form, stampers start not with choosing equipment but evaluating the metal itself. Properties of the sheet metal used will give the designer information about how to make changes to the process to effectively get the material to form into the desired shape.
Before stamping, the stamper will cut a piece of sheet metal. How closely this metal resembles the finished piece determines what it’s called. This process of creating blanks may occur with a particular die or with another means of cutting, depending on the size of the metal needed.
- Undeveloped blank: Undeveloped blanks are cut into any shape using straight lines and use more metal than the finished piece. These blanks require trimming after shaping, often leading to metal scraps at the end of the process.
- Semi-developed blank: Closer in size to the final part, semi-developed blanks still need trimming after formation to create the finished component. However, most stampers prefer to use this type of starter part because it blends the best of reducing waste while still giving the operator extra material to work with during the stamping process.
- Fully developed blanks: More work goes into creating fully developed blanks even before these pieces of sheet metal reach the press. These pieces have no extra material, which makes them more likely to spring back, but they do not need trimming after shaping.
Some metals require special considerations due to their extra strength or flexibility, which makes forming them more difficult. High-strength, thin metals can have extra springback. To prevent the part from losing its shape, it must have enough stress put into the metal to go beyond the material’s yield point, where it stays in its bent form. Metal designers may use an undeveloped blank because these quadrilateral shapes have extra material that allows for better gripping and forming over the die. If the process requires little to no trimming of additional metal after the formation of the part, the designer may use instead semi-developed or fully developed blanks, but these make the process of stamping robust and thin material more difficult, though not impossible.
Understanding the properties of the sheet metal makes the process easier for the stamper to create the shape required without making costly mistakes. Planning before putting the metal to the dies will ensure the process runs as efficiently as possible.
The process of stamping requires knowing about the metal, its properties and the desired attributes of the finished project. These, along with the design of the product, will give engineers the information needed to run a simulation before production.
Simulations predict weaknesses in the design or metal that could cause breaks or malformations in the finished product. Once simulations finish, the completed computer model is ready for transfer to the presses.
Presses used for the stamping process require professional use. These machines typically can exert forces between 10 and 50,000 tons and are highly dangerous for the untrained. Such forces are necessary to stretch, press or cut the metal fed into them. The presses operate the dies that shape the metal. Because these machines have automated functions, operator error plays a lower role in their production. Both the caliber of the die and the press play critical roles in the efficiency of the process and quality of the finished parts.
In the progressive die stamping process, the blank moves through a series of tools to shape and form the metal, each die performing a different task to finish the project. Cutting and shaping may both occur during the process. Both require a variety of specialized dies to create the desired cut or form.
Die cutting creates specific shapes needed to work the metal toward its final form. When cutting metal, the material will often stretch and rebound during the process, causing it to adhere to the die. A stripper pulls the cut portion off the die. Cutting entails multiple types of dies, based on the shape of the desired result. Some cutting processes include trimming, piercing and more.
- Trimming: Trimming tends to be a finishing process that removes excess metal from the piece. The trimmed metal, called offal, gets recycled to reduce waste and increase efficiency. Notching is a similar cutting option that creates small notches in a metal strip used in progressive dies.
- Piercing: Piercing creates a shape in the metal. The shaped slug gets discarded while the rest of the metal moves to the next step in the process.
- Blanking: Blanking creates the basic shapes the process will later form. This cutting retains the slug for future use to reduce waste.
- Shearing: Shearing uses straight cuts to create quadrilateral shapes with no slugs.
- Lancing: When a stamper needs notches in a strip of metal for progressive dies, they use lancing to create cuts in a flex web. Since lancing does not produce slugs, this cutting process does not need scrap removal, saving time and money.
For shaping metal, dies bend, stretch or curl the material. Stampers must know how each of these processes affects the strength and thickness of the metal. For instance, stretching thins the metal, which can reduce its original strength. Part of choosing which shaping tasks a component needs depends on what attributes of the original metal the piece needs to retain in addition to the finished shape. The exact functions used for forming metal rely on the product’s shape, but some processes shaping may entail include the following:
- Stretching: Stretching pulls metal blanks over a form to thin the material while forming it.
- Bending: Bending creates corners and angles along straight edges on the material.
- Coining: Coining puts high pressure onto the metal to force parts in the desired shapes out of the blank. The name for this process comes from its use to create metal currency.
- Drawing: Dies created for drawing metal move the metal to form the shape. Unlike stretching, drawing has a constant inward metal movement.
- Flanging: Flanging uses a flanging die to create a curved bend in the metal. Two types of flanges exist — tension, which may split, and compression, which may wrinkle.
- Embossing: Embossing stretches metal to create depressions in the metal for images or lettering.
- Ironing: Like the ironing of clothing, ironing metal compresses it into a thinner sheet.
- Reducing: Reducing shrinks the diameter of a rounded part, such as bringing a gun shell to a point.
- Hemming: Hemming folds an edge of metal over itself to create a reinforced hem, similar to those seen on clothing edges.
- Curling: Curling creates curved edges, like those on hinges.
- Extruding: With extrusion, the metal moves while it’s stretched to enlarge a hole in the design.
The entire stamping process may occur at one station or many. The differences between these determine how the parts appear on the metal.
- Single station: For single-station stamping, everything occurs at once workstation, usually using one method.
- Progressive stations: For multi-step processes, stampers use progressive die stamping, which holds all the parts onto a strip until they finish the process. At the end of the process, the creator must remove the finished pieces from their shared strip. Despite the need for this extra step at the end, the ability to stamp multiple parts through a series of dies dramatically makes up for the extra time required.
Find out More From DIE-TECH
Discover more about our progressive die stamping process at DIE-TECH. We have experience in creating projects others failed at finishing. After 41 years in the industry, we have engineered our method to be as cost-effective and efficient as possible. Our engineers work with you from start to finish to create the metal designs you require. See what we can do with your project by contacting us or requesting a quote.