How to Design Thin Walls for CNC Machining

In the world of precision CNC machining, designing parts with thin walls is a common yet challenging requirement, especially for applications in aerospace, medical devices, and electronics where weight reduction and material efficiency are paramount. However, pushing the limits of thinness without considering manufacturability can lead to part failure, vibration, and increased costs. Mastering the design of thin walls is key to creating highperformance, reliable, and costeffective components.


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The primary challenge with thin walls is their lack of rigidity. During machining, cutting forces can cause these fragile features to deflect, vibrate, or even break. This results in poor surface finish, dimensional inaccuracies, and potential scrapping of the part. To mitigate these issues, designers must follow key principles.

First, material selection is fundamental. Some materials are inherently better suited for thinwall structures. Aluminum alloys, like 6061, are a top choice due to their excellent strengthtoweight ratio and machinability. Plastics such as PEEK and Delrin also perform well. Conversely, harder materials like stainless steel or titanium are significantly more challenging to machine into thin walls and often require specialized processes.

Second, adhere to general thickness guidelines. While capabilities vary, a good rule of thumb is to maintain a minimum wall thickness of 0.020 inches (0.5 mm) for metals and 0.040 inches (1.0 mm) for plastics. Whenever possible, design walls thicker than these minimums. A wall of 0.040 inches in aluminum is far more robust and easier to produce than one at 0.020 inches.

Third, incorporate smart design features. Avoid tall, unsupported thin walls. The aspect ratio (heighttothickness) is critical; keeping it below 10:1 is a safe target. Use corner fillets and radii generously. Sharp internal corners concentrate stress and are difficult to machine, whereas a generous fillet significantly strengthens the junction between walls. Furthermore, adding strategic ribs or gussets can dramatically increase stiffness without adding substantial mass.

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Finally, collaborate with your machining partner early. A seasoned manufacturer can review your designs and suggest adjustments for optimal manufacturability. They can advise on toolpath strategies, fixturing solutions, and the order of operations to minimize stress on thin features.

At our onestop CNC machining shop, we specialize in transforming complex designs, including those with challenging thin walls, into highquality, precision parts. By partnering with us, you leverage deep expertise in Design for Manufacturability (DFM) to ensure your parts are not only functional but also economical and reliable. Let us help you optimize your designs for success.