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Metal stamping offers an affordable method of producing metal parts with beneficial properties such as stability, wear resistance, durability, and strength. Through processes like bending, piercing, punching, and blanking, metal stamping can produce high-quality components for a range of applications.
When designing your metal stamping project, it’s important to understand and follow the fundamentals of each forming process to avoid costly errors, ensure optimal quality, and meet your expectations for costs and lead times. Here, we will go over some basic general guidelines and formulas to use during the metal stamping design process to ensure cost-effective, high-quality parts.
Metal Stamping: Sheet Metal Design Guidelines
During the metal stamping design process, it’s important to consider the following guidelines:
Holes
When using metal stamping to create holes, the hole diameter should always be equal to or more than 1.2 times the thickness of the material. If the metal has high tensile strength, such as stainless steel alloys, the minimum diameter of the hole should be at least two times wider than the material’s thickness.
Edge to Holes
There should be a distance of two stock thicknesses between hole and edge. If the holes are oblong and less than 10 material thicknesses in length, edge-to-hole spacing should be two times the material thickness. However, if the oblong holes are greater than 10 material thicknesses, the edge-to-hole spacing should be four times the material thickness or more to prevent bulging.
Hole to Form
Hole deformation can occur when forming a bend too close to a hole. To prevent this, the spacing should be the bend radius plus 2.5 times the material’s thickness. If the hole’s diameter or width is less than 2.5mm, the distance between the hole and the bend must be a minimum of twice the material’s thickness plus the bend radius. If the hole is more than 2.5mm in width or diameter, the distance should be the bend radius plus 2.5 times the thickness of the material.
Slot to Form
When bending near long slots, the spacing must be the bend radius plus a minimum of four times the material’s thickness to prevent deformation.
Notches & Tabs
When stamping notches and tabs, the formations should not be less than 1.5 times the thickness of the material. If made smaller, they may experience breakage due to the amount of force exerted on punches.
Corners
When forming corners, it’s important to be as generous as possible to facilitate manufacturing. The radius of the punch and die should be at least four times the thickness of the material. Corners can be very sharp if you’re working with a material that is 1.5mm or less in thickness.
Squareness
Stamping to form a square, 90° angle allows for normal variation of plus or minus 1 degree.
Flatness
Flatness should not be over-specified. A component requiring a flatness of fewer than .003 inches may require costly secondary operations.
L-Shaped Parts
When stamping L-shaped parts, a bend relief notch should be included to avoid fractures and cracks.
Grain Direction
When stamping hard stocks, consider grain direction. To prevent cracking and fractures, the bend line of sharp V-bends should not be parallel to the grain direction. On harder materials, a larger bend radius may also be required to avoid cracking.
Burrs
Burrs can be a common occurrence in stamping. When they occur on the outside of a bend, they can create fractures. Burrs can reach heights up to 10% of the material thickness, and they can be removed using various processes. To minimize burr severity, you should avoid complex cutouts and sharp corners when possible. If these can’t be avoided, it’s important to note the burr direction in the design so they can be taken into account during the metal stamping process.
Shapes
A round shape is the simplest to draw, followed by a square shape with sufficient corner radii. If a shape combines two basic shapes or is irregular, it may increase stamping difficulty and the cost of production.
Feature Distortion
Distortion can occur during stamping when holes and slots are too close to a form, edge, or each other. This is especially true in drawn parts, which tend to experience much more deformation compared to formed parts.
Speak to the Metal Stamping Experts at Aranda Tooling
Paying close attention to metal stamping design best practices can improve cost efficiency and lead times while preventing excess waste due to errors. Aranda Tooling has been a leader in metal fabrication, custom metal stamping, and more since 1975, and we can work with you to ensure the optimal metal stamping design for your needs. To get started on your metal stamping solution, contact us or request a quote today.