Design for Manufacturing Tips
Practical design tips to reduce cost and improve quality in CNC machined parts. Draft angles, wall thickness, and tolerance callouts.
Design Tips for CNC Machined Parts
1. Specify Functional Tolerances Only
Not every dimension needs ±0.005 mm. Over-tolerancing increases cost and inspection time. Specify tight tolerances only on mating surfaces, critical diameters, and alignment features. General dimensions can use ISO 2768-mK or similar defaults.
2. Design for Tool Access
Internal corners should have a radius larger than your smallest available tool (typically 0.5 mm or larger). Deep pockets need consideration for tool length-to-diameter ratio. Avoid features that require special custom tools if standard tools can achieve the function.
3. Wall Thickness
For aluminum, maintain wall thickness at 0.8 mm or greater for machinability. For steel, 1.0 mm minimum. Thin walls flex under cutting forces, causing chatter and poor surface finish.
4. Material Selection
Choose the material that meets your functional requirements at the lowest cost. 6061 aluminum covers most general-purpose needs. 7075 for high stress. 316L stainless for corrosion. PEEK for temperature and biocompatibility.
5. Feature Consolidation
Combine features into fewer parts when possible. A single 5-axis setup can produce geometries that would otherwise require multiple operations and fixturings.
6. Provide Complete 2D Drawings
Include thread specifications, surface finish requirements, edge breaks, and critical datums. The more complete the drawing, the faster and more accurate the quote.