Metal stamping is a fast, cost-effective type of metal forming for creating precise parts from metal materials such as sheets and coils. Keats Manufacturing Co. is a leading provider of comprehensive and accurate metal stamping, finishing, and value-added services. We can guide you through the metal stamping process to help confirm what procedures and finishes are necessary for your product, and we have the expertise to avoid the pitfalls of metal forming by using industry best practices in your product design.
Metal Stamping Manufacturing Process
Metal stamping is a cold-forming manufacturing process that encompasses a broad series of steps for transforming flat metal sheets into unique shapes with features such as bends, holes, grooves, and slots. Some of the individual processes that metal stamping manufacturers use include:
Blanking
Blanking converts a large, generic sheet of metal into smaller forms for further bending and processing. During blanking processes, machinery might cut the sheet with high-speed dies utilizing long strokes through the metal or have dies that cut out specific shapes. This process is fast and ensures each workpiece is an appropriate size and shape.
Bending
Manufacturers can create precise bends in metal workpieces to give them a more unique dimensional form. Alloys and metals that are less brittle are generally more formable, while stiff metals and alloys are more restricted when it comes to creating 90° or sharper bends. Not only is there a bigger risk of cracking, but the metal may also try to bend back to its original form.
Piercing
Piercing is a popular technique to create cutouts within a strip of metal or metal part. Rather than using a die to shape a workpiece into a specific, desired form and discarding the excess material around the die shape, piercing does the reverse: The stamped-out material removal creates slots or holes in a workpiece, with the remaining metal being the desired form.
Coining
Coining is a metal forming process that exposes a component to high levels of stress and pressure. This generates a plasticized flow of material so the workpiece has smoother surfaces and edges and is more closely aligned to the tolerances of the design.
Drawing
In drawing processes, the material edges hold in place and a punch from one side of the workpiece forces the metal to take the form of the die on the other side. This draws the workpiece into a new shape.
Embossing
Embossing processes create raised characters or designs on a stamped workpiece for a tactile finish. The workpiece typically passes between male and female dies, which deform specific lines of the workpiece into the new shape.
Punching
This process involves a press pushing a punch through a metal form to leave behind a hole with a precise shape and placement. The punching tool often completely separates the excess material from the newly created form. Punching can occur with or without shear.
Curling
Curling processes crimp or join edges to form a ring of material with a hollow center. An example result of this process is door hinges.
Types of Metal Stamping
There are multiple different types of metal stamping that can produce products with different characteristics. Three common types used at Keats Manufacturing are:
Progressive Die Stamping
In progressive die stamping, metal material moves through multiple workstations, each of which uses a different die to stamp or bend the metal into the correct form. At the end, the machine will free the formed part from its metal sheet. This process is popular for creating fast orders of complex components or long production runs.
Transfer Die Stamping
Transfer die stamping is somewhat alike progressive stamping, but rather than remaining connected to the original metal strip, each workpiece first separates into a distinct piece before the stamping process and then mechanically moves to the next station. This process is suitable for larger components.
Four-Slide Stamping
In four-slide stamping, four slides or rams form a component by systematically pressing into it from all four sides utilizing the machine’s shafts and cams. The process can create complex forms and has the added benefit of changeability for altering workpiece design.
Metal Stamping Design Considerations
Sheet metal and coiled metal wire are the most common materials used in metal stamping processes. To create well-formed, accurate, and virtually identical products, it’s important to consider these elements when creating metal stamping designs:
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Bend radius
The material must generally bend in a single orientation, and the inside bend radius should equal the sheet thickness at a minimum. -
Grooves, holes, and slots
Keeping the diameter of grooves, holes, and slots equal to or larger than sheet thickness results in better form with fewer burrs and bulges. Keeping the holes apart at a distance of at least twice the thickness of the material can also reduce bulging and deformation. -
Material needs and characteristics
Different metals and alloys have different attributes, including different degrees of resistance to bending, strength, formability, and weight. Some metals will respond better to design specifications than others; conversely, designers will need to take the advantages and limitations of their chosen metal into consideration. -
Tolerances
Determine the acceptable tolerance levels for your project. Achievable tolerances will vary based on the metal type, the design demands, and the machining tools used. -
Wall thickness
Consistent wall thickness throughout a product is typically ideal. If a part has walls with different thicknesses, then it will be subject to different bending effects, resulting in deformation or falling outside of your project’s tolerances.
Possible Defects and How to Avoid Them
Some of the most common defects in metal stamped products are:
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Bending damage
Parts with dramatic bends are particularly vulnerable to cracks, especially if they’re made from stiff metals with little plasticity. If the bend is parallel to the grain direction of the metal, it could form long cracks along the bend. -
Hole deformation
Three-dimensional metal parts with holes often go through hole punching first and bending into shape second. If the holes are too close to the bent edge, they can stretch or deform. -
Insufficient hole spacing
If a hole isn’t a proper distance from the edge of a piece, which is a minimum of twice the part’s thickness, then the strip of material between the hole and the edge will bulge outward. -
Stamped edge burrs
Cutting and stamping tools can shear metal edges, causing sharp burrs along the bottom of the edge. This can make the piece sharp to the touch, lead to a blemished finish, or even negatively impact the dimensionality of the finished product.
These defects are often the result of poor stamping processes and deviation from best practices.
Choose Precision Metal Stamping Services From Keats Manufacturing
Keats Manufacturing is a custom metal stamping supplier specializing in high-quality metal stamping, wire form, and assembly services. Our engineering and production teams have the experience and skill to tackle your project, no matter how complex, all at an affordable cost.
To learn more about our stamping capabilities for custom parts, low- and high-volume production runs, and more or for pricing details
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