CNC machining delivers precision and consistency, but costs can escalate quickly without proper planning. Whether you’re producing prototypes or large batches, optimizing your approach can lead to significant savings. Here are 10 proven strategies to reduce CNC machining costs while maintaining top quality.
1. Optimize Part Design for Manufacturability (DFM)
Smart design choices directly impact machining costs. Complex geometries, deep pockets, and unnecessary features increase production time and material waste.
Key DFM principles:
- Use standard drill sizes to avoid custom tooling
- Design internal corners with radii matching standard end mills
- Avoid excessively thin walls (<0.5mm) that require special handling
- Minimize deep cavities (>4x tool diameter) that need extended reach tools
Pro Tip: Use CAD simulation tools to identify potential manufacturing challenges before sending files to production.
2. Select Cost-Effective Materials
Material choice affects:
- Machining time
- Tool wear
- Scrap rates
- Overall part cost
Most economical options:
- Aluminum 6061: Excellent machinability, good strength-to-weight ratio
- Plastics (Delrin, Nylon): Faster machining than metals for non-structural parts
- Mild Steel: Affordable alternative to stainless for many applications
Avoid when possible: Titanium, Inconel, and other superalloys that dramatically increase machining costs.
3. Choose the Right Tolerances
Tighter tolerances = higher costs. Only specify precision where absolutely necessary.
Cost-saving tolerance guidelines:
- Standard tolerance: ±0.1mm
- High precision: ±0.005mm – adds 20-50% to cost
- Critical surfaces: Apply tight tolerances only to mating/functional areas
4. Maximize Batch Sizes to Reduce Costs
CNC machining has high setup costs but low marginal costs per additional part.
Economic order quantities:
- Prototypes: 1-5 pieces
- Small batch: 10-50 pieces (best cost balance)
- Production: 100+ pieces (lowest per-unit cost)
Strategy: Combine multiple parts in single orders to share setup costs.
5. Optimize Machining Process Selection
Different CNC methods have varying cost structures:
| Process | Best For | Cost Factor |
| 3-Axis Milling | Simple parts | $ |
| 5-Axis Milling | Complex geometries | $$$ |
| Turning | Cylindrical parts | $ |
| Swiss Machining | Small, precision parts | $$ |
Rule: Use the simplest process that meets your requirements.
6. Reduce Machining Time
Since shops charge by the hour, faster machining = lower costs.
Time-saving techniques:
- Use largest possible tools for roughing
- Optimize toolpaths to minimize air cutting
- Consider high-speed machining for aluminum
- Design parts to minimize required tool changes
7. Minimize Secondary Operations
Each additional process adds cost:
Common cost drivers:
- Surface finishes beyond standard Ra 32
- Special coatings or treatments
- Manual deburring
- Precision grinding
Solution: Design parts to come off the machine ready for use when possible.
8. Standardize Features
Design consistency across parts reduces setup time and tooling costs.
Standardize:
- Thread sizes
- Hole diameters
- Corner radii
- Fastener types
9. Consider Alternative Manufacturing Methods
For some applications, hybrid approaches save money:
Cost-effective alternatives:
- Extrusion + CNC finishing
- Casting + CNC machining
- Sheet metal fabrication for flat parts
10. Partner with the Right Machine Shop
An experienced manufacturer can suggest how to reduce CNC machining costs.
Look for:
- Modern equipment (reduces cycle times)
- Material expertise (can suggest alternatives)
- Design feedback (optimization suggestions)
- Volume discounts
Ask potential vendors:
- What design changes could reduce costs?
- Do you offer quantity discounts?
- What’s your scrap rate for this material?
Bonus: Cost Comparison Table
| Factor | Low Cost Approach | High Cost Approach |
| Material | Aluminum 6061 | Titanium |
| Tolerances | ±0.1 mm standard | ±0.005 mm all surfaces |
| Quantity | 100+ pieces | 1-2 prototypes |
| Features | Standard holes | Custom thread forms |
| Finishing | As-machined | Mirror polish |
Final Cost-Saving Checklist
Before ordering your next CNC machined parts:
- Simplified design (DFM optimized)
- Appropriate material selected
- Tolerances relaxed where possible
- Batch size maximized
- Secondary operations minimized
By implementing these 10 cost-reduction strategies, you can typically achieve 20-40% savings on CNC machining projects without compromising quality.
Need help optimizing your design for cost-effective machining? [Get a free DFM analysis] from our engineering team today!