Custom machined parts that follow Design for Manufacturing (DFM) rules lower production costs while also producing a better quality component. These simple design guidelines can optimize the manufacture of CNC machined parts that require high dimensional accuracy and tight tolerances. This includes low-volume prototypes or high-volume, end-use products.
At Stuecklen Manufacturing Company, serving both the U.S. and Canada, we pride ourselves on our high-quality CNC machining services, and we’re here to help you get the best end product.
7 Design Tips for CNC Machined Parts
1. Consider tool geometry and tool access
To overcome the access limitations of the cutting tool, try to keep holes, vertical walls, and cavities aligned to one of the main directions of the CNC machine. Also, use the largest possible diameter tool with the shortest length possible.
2. Designing cavities and pockets
The recommended cavity depth is 4 times the cavity width. Applying this limitation will reduce CNC machine vibrations and tool deflection, while also assisting in chip evacuation.
3. Recommend internal edge practices
Draft internal corner radii to be 1/3 of the cavity depth (or greater if possible) for a higher-quality finish and for easier selection of a suitable diameter tool. Floor radius recommendations are 0.5 mm, 1 mm, or no radius at all.
4. Consider wall thickness
The minimum wall thickness best practice for metal is 0.8 mm and 1.5 mm for plastics. CNC machined parts with walls that are too thin will be less stiff and result in lower dimensional accuracy. Use the largest wall thickness possible for plastics to reduce failures such as warping due to residual stresses and softening as material temperature increases.
5. Use standard hole sizes
Always attempt to design holes that fit standard drill bit sizes for drills, end mills, reamers, and borers in metric and imperial units. The recommended hole depth is 4 x nominal diameter up to 10 x nominal diameter. The minimum threaded hole should be an M2 (with a thread length of 1.5 x nominal diameter minimum), while M6 or larger threads are recommended (with a thread length of 3 x nominal diameter).
6. Preferred design tolerances
Follow reasonable guidelines when applying geometric tolerances to components. A standard tolerance of ± 0.125 mm (0.005”) gives good results and is recommended when no tolerance is specified. Otherwise, try to limit machined precision to ± 0.025 mm (0.001”).
7. Small geometric features
Keep small cavities and holes to diameters that require using tools down to 2.5 mm (0.1”) in diameter. Otherwise, you may require special micro-machining drills along with expert knowledge on how to maintain good tool performance.
Observing these design rules for custom machined parts will reduce both manufacturing costs and scrap production. When you understand the preferred rules for CNC machined parts, highly precise components can be easily produced.
Learn More About Stuecklen Manufacturing’s High-Quality CNC Machining
To learn more about our services and what we can manufacture for you, contact Stuecklen Manufacturing Company, a leader in CNC machining service with one of the largest CNC hydroforming machines in the country.
