Metal Stamping Design Standards and Guidelines

Metal stamping is a cornerstone in manufacturing, transforming metal sheets into various shapes and forms through high-precision tools and dies. It’s a dance of engineering – shaping, cutting, and forming metal in an almost magical way. But this magic doesn’t happen by chance. It results from meticulously following design standards and guidelines, the unsung heroes of the metal stamping process.

This blog will explore the intricacies of these design standards and guidelines. From the specifics of hole and slot dimensions to the subtleties of bends and forms, we will cover the crucial aspects that every professional in the metal stamping industry should know. So, let’s dive in and uncover the secrets of successful metal stamping design!

Holes and Slots

Holes, the void spaces punched out of the metal, and slots, essentially elongated holes, provide points for fastening, reducing weight, and facilitating component alignment.

Design Considerations

Designing holes and slots requires a careful balance between the part’s functionality and the limitations of the stamping process.

• Minimum Hole Diameters: A cardinal rule in stamping design is that the diameter of a hole should never be less than the material thickness. This guideline helps to avoid material tearing and maintains the part’s structural integrity. For instance, if you’re working with a 2mm thick sheet, your hole diameter should be at least 2mm.
• Slot Width Standards: Regarding slots, the width should also adhere to the material thickness rule. However, the length can be varied based on design requirements. It’s crucial to ensure that the slot width is narrow enough to prevent tooling difficulties and material distortion.
• Hole and Slot Positioning: The positioning of holes and slots is just as important as their size. They should be placed far from the edges and other features to prevent material weakening. A general guideline is maintaining a distance of at least twice the material thickness from any edge or another hole/slot. This spacing helps in maintaining the structural integrity of the stamped part.

Bends and Forms

Bending in metal stamping is an art form that transforms flat sheets into shapes with purpose and function. It’s not just about bending the metal; it’s about understanding how it behaves under stress. 

There are various types of bends – V-bends, U-bends, and offset bends, each serving different structural and aesthetic purposes. The material’s behavior during bending, like spring back and stress concentrations, is critical to the process. In essence, bending is not just shaping; it’s engineering the metal to serve a specific function while maintaining its integrity.

Design Standards

Regarding bending in metal stamping, several design standards ensure the part’s durability and functionality.

• Recommended Bend Radii: One key aspect is the bend radius, which should equal the material thickness to avoid cracking or weakening. For example, if you’re working with a 1mm thick steel sheet, the bend radius should be no less than 1mm.
• Bend Angle Tolerances: Precision is paramount in bending angles. Adhering to tight tolerances ensures that the parts fit together seamlessly in assembly. Typically, a tolerance of ±1° is a good standard for most applications.
• Grain Direction Considerations: The direction of the metal’s grain plays a significant role in bending. Bending perpendicular to the grain direction can lead to cracking and should be avoided. Aligning the bend with the grain direction maximizes the part’s strength and longevity.

Also, special considerations like bending height and bends close to edges are crucial. Bends near edges require reinforcement to avoid distortion, and the height of the bend should be consistent to maintain uniformity across the part.

Burrs

Burrs in metal stamping are like uninvited guests at a party – they’re often there and usually unwelcome. A burr is a rough or sharp edge left on a metal part after stamping, resembling a fine metallic fringe. These small pieces of metal can affect part fit, function, and even safety. They’re a byproduct of the shearing action in stamping, where the metal is cut or punched. 

Minimization Strategies

The key to dealing with burrs is not just removal but prevention and minimization through intelligent design and process control.

• Design Modifications: One effective way to reduce burr formation is through thoughtful design alterations. This might include changing the shape or angle of a cut to reduce stress concentrations, which can lead to burr formation.
• Post-Stamping Processes: Despite best efforts in design, some burrs may still form. In such cases, post-stamping processes like deburring, which involves mechanically smoothing the edges, become essential. Techniques like tumbling are commonly employed, where parts are agitated with abrasive media or manual deburring for more delicate or complex parts.

Corner Radii

In metal stamping, corner radii are more than just a design feature; they are a crucial element in the part’s structural integrity and aesthetic appeal. Sharp corners can be stress concentrators, leading to cracks and failure in service. Conversely, well-designed corner radii can distribute stress more evenly, enhancing the part’s durability. 

In terms of aesthetics, smooth and consistent corner radii contribute to a more finished and professional look, which is particularly important in consumer-facing industries like automotive and electronics.

Design Guidelines

When it comes to corner radii, there are specific guidelines that should be followed to strike the right balance between strength and manufacturability.

• Minimum and Maximum Corner Radii: The minimum radius should be equal to the material thickness to avoid cracking, while the maximum radius is often dictated by the part’s functional and aesthetic requirements. For instance, a larger radius may suit parts requiring a smoother, rounded appearance.
• Balancing Strength and Manufacturability: It’s essential to consider both the strength and ease of manufacturing when determining the corner radius. A small radius might weaken the part, while a small radius may complicate the stamping process or the tooling required. Finding that sweet spot is critical to a successful design.

Tabs and Notches

Tabs are small protruding pieces, and notches and cut-out sections serve several critical purposes. They aid in alignment and assembly, act as stop features, and can even be used for electrical contacts in electronic components.

Design Principles

When incorporating tabs and notches into metal stamping designs, there are fundamental principles to follow to ensure they are effective and do not compromise the part’s integrity.

• Size and Placement Guidelines: The size of tabs and notches should be proportionate to the part’s overall dimensions and the material thickness. Placement is equally important; they need to be strategically located to serve their intended purpose without weakening the part. For instance, placing a notch too close to a bend can lead to material stress and potential failure.
• Avoiding Common Design Errors: One of the common errors in designing tabs and notches is neglecting to account for the stamping process’s impact on material properties. For example, a too thin tab may bend or warp during stamping, while a notch that is too deep may compromise the part’s structural integrity.

Dimensions and Tolerancing

Accurate dimensions ensure that each part fits perfectly in its intended place, functioning seamlessly as part of a larger assembly. 

Tolerances, the permissible limits of variation in a physical dimension, are crucial in determining how well parts will fit together and operate in real-world applications.

Standard Practices

Adhering to industry standards and best practices in dimensions and tolerancing is essential for ensuring the quality and functionality of stamped parts.

• Industry-Standard Tolerances: These tolerances are often defined by industry norms and specific customer requirements. They are critical in guiding the manufacturing process to produce parts that meet the expected levels of precision. For instance, the standard tolerances for general metal stamping differ from those required in the medical device industry, which demands even higher accuracy.
• Dimensioning Techniques for Stamped Parts: Effective dimensioning involves more than just specifying measurements. It includes understanding how different dimensions interact with each other and the stamping process. This might include considering factors like material thickness variations, bend allowances, and the cumulative effects of multiple features on a part. It’s about foreseeing how each dimension can affect the final product and planning accordingly.

Conclusion

In conclusion, whether you are an experienced engineer or new to metal stamping, keeping these guidelines at the forefront of your design process is essential. They are the pillars that support the structural integrity of the parts we create and the trust and confidence our clients place in our products. Let’s strive for excellence in every stamp, bend, and cut, ensuring that our products are manufactured and masterfully crafted.

For more insights and assistance in precision metal stamping, feel free to contact us at Worthy Hardware. We’re here to help you turn your designs into reality with the highest standards of precision and quality.