10 Design Tips to Make Your CNC Parts Stronger, Cheaper & Faster to Produce
Introduction
Designing a part is only half the journey — making sure it can be manufactured efficiently, accurately, and cost-effectively is just as important. Whether you're developing a prototype or preparing for full production, applying strong Design for Manufacturability (DFM) principles can significantly reduce machining time, improve part performance, and lower overall cost.
Here are ten practical engineering tips to help you get the most out of CNC machining and create parts that are easier and more economical to produce.
1. Keep Tolerances Tight Only Where Necessary
Tight tolerances increase machining time and cost. Many surfaces don’t require ±0.001" precision.
Use strict tolerances only on mission-critical features such as mating surfaces, shafts, bores, and precision fits.
2. Use Standard Hole Sizes and Tools
Designing holes to standard drill sizes reduces tool changes and setup time.
Avoid unusual diameters unless the function demands it.
3. Optimize Wall Thickness
Extremely thin walls cause vibration and require slower cut speeds.
Recommended minimum:
Aluminum: 0.030–0.040"
Steel: 0.060"
Thicker walls = stronger parts + faster machining.
4. Add Fillets to Internal Corners
CNC tools are round, not square.
Sharp internal corners require extra cutting steps or EDM.
Add fillets (preferably radius ≥ tool radius) to reduce machining time and improve tool life.
5. Simplify Complex Geometry When Possible
Eliminating unnecessary pockets, deep cavities, undercuts, or decorative features can dramatically lower machining costs.
Ask yourself:
Does this feature add functional value?
6. Avoid Extremely Deep Pockets
Deep pockets are slow to machine and can cause tool chatter.
For pockets deeper than 4× the tool diameter, consider:
multiple-step designs
reducing depth
redesigning the part into two components
7. Choose Materials Wisely
Material hardness affects machining speed and cost.
Fastest & most economical:
Aluminum 6061/7075
Plastics (Delrin, Nylon, PTFE)
More costly & time-consuming:
Stainless steel
Titanium
Inconel
Choose materials based on strength, budget, and application requirements.
8. Design for Standard Tool Access
If a tool can’t reach a feature, the part becomes more expensive.
Avoid:
extremely narrow channels
deep grooves
unreachable back-side features
Ensure clear tool paths or redesign features for accessibility.
9. Combine Features to Reduce Setup Time
Parts requiring multiple setups or workholding positions add cost.
Where possible, align features so they can be machined in fewer setups, improving precision and lowering production time.
10. Consult with Your Machinist Early
The best designs come from collaboration.
Sharing your CAD model early allows your machining partner to:
suggest improvements
lower costs
prevent errors
optimize manufacturability
At Universal Machining & Engineering, our engineering team works directly with customers to ensure every part is designed for precision, performance, and efficiency.
Conclusion
Strong DFM practices lead to stronger parts, faster production, and lower costs. By considering tool access, material selection, tolerances, and geometry early in the design phase, you set your project up for success.
If you're working on a new prototype or production run, we’re here to help you optimize your design for the best results.
