How to Get Perfectly Formed Sheet Metal Parts Every Time (Updated for 2025)

Solution 2: Software and Custom Sheet Metal Dies

To achieve a perfect complex bend every single time, forming software with precision sheet metal dies is the best solution.

Dies can be custom-made to cut and form a part according to the specified design. To create a deep U shape, for example, a “gooseneck” or “swan neck” die could be used to achieve the shape successfully.

At Approved Sheet Metal, our software can analyze the shape of your part to make sure we select the right die for the job. We have dies in many different shapes and sizes, and 90% of the time, we’ve already got the right die to match your project needs (the other 10% of the time, we’ll custom-order or come up with another solution to get the job done).

We have a wide range of sheet metal dies, including:

• Embossing Dies
• Punch Dies
• Cutting Dies
• Coining Dies
• Bending Dies
• Flanging Dies

Tolerance Stack-Up and Design for Manufacturability (DFM)

When designing precision sheet metal parts, understanding tolerance stack-up and design for manufacturability (DFM) is crucial to ensuring that the final assembled product meets specifications without costly rework or fitment issues.

Understanding Tolerance Stack-Up

Tolerance stack-up refers to the cumulative effect of individual part tolerances within an assembly. Informed design choices help prevent dimensional inaccuracies that could cause misalignment, interference, or assembly failures.

• Linear Tolerance Accumulation – Each bend introduces variation, and multiple bends in sequence can lead to greater deviations in the final part dimensions.
• Perpendicularity and Flatness Considerations – Improper tolerance control can lead to unwanted gaps or stress during assembly.
• Material Springback – Certain materials, like stainless steel and high-strength alloys, exhibit more springback, requiring compensation in the design stage.

DFM Strategies for Precision Sheet Metal Forming

To minimize manufacturing challenges and optimize cost-effectiveness, follow these best practices:

1. Use Realistic Tolerances

   • Tight tolerances increase manufacturing costs and may require secondary processes like machining.
   • Apply looser tolerances where possible and only tighten them in critical areas affecting function and assembly.

2. Standardize Bend Radii and Features

   • Use common bend radii that align with available press brake dies to reduce setup time and tooling costs.
   • Minimize complex or small-radius bends in thick materials to prevent cracking.

3. Consider Assembly Fit and Fastening Methods

   • Allow for clearance holes and slots to accommodate tolerance variations in mating parts.
   • Optimize fastener placement to prevent stress concentrations and distortion during assembly.

4. Control Flatness and Warping

   • Large flat sections in thin materials may warp due to internal stresses.
   • Introduce stiffening ribs or strategically placed bends to enhance rigidity.

5. Leverage GD&T (Geometric Dimensioning and Tolerancing)

   • Use position tolerances instead of linear dimensions where appropriate to improve manufacturability.
   • Apply datum structures to control critical features without over-constraining the design.

By proactively addressing tolerance stack-up and applying DFM principles, engineers can design parts that are not only manufacturable but also cost-effective and reliable in real-world applications. Would you like to include a case study or example to illustrate these principles further?