CNC Machining Cost: Factors That Affect Pricing
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Introduction
"How much will it cost?" is the first question every engineer and buyer asks. CNC machining pricing isn't arbitrary — it follows predictable patterns based on specific cost drivers. Understanding these factors puts you in control of your project budget.
This guide breaks down the 7 key factors that determine CNC machining costs, with actionable tips to reduce your per-part price.
1. The 7 Cost Drivers
Factor 1: Material Choice
Material cost varies by 10× or more:
| Material | Relative Cost/kg |
|---|---|
| Aluminum 6061 | 1× (baseline) |
| Mild Steel 1018 | 0.8× |
| Stainless 304 | 2.5× |
| Brass C360 | 3× |
| Titanium 6Al-4V | 15× |
| PEEK | 20× |
| POM (Delrin) | 2× |
| PTFE | 4× |
Cost-saving tip: Use 6061 aluminum unless you specifically need another material's properties. It's the cheapest metal per kg and machines fastest.
Factor 2: Part Complexity
Every feature adds machining time:
| Feature | Time Impact |
|---|---|
| Simple 2.5D prismatic | Baseline |
| 3D contoured surfaces | +50-200% |
| Tight internal corners (no radius) | +50-100% (EDM required) |
| Deep pockets (>4:1 depth:width) | +30-80% |
| Thin walls (<1mm) | +30-50% |
| Multiple setups (flip part) | +50-100% per setup |
Factor 3: Tolerances
| Tolerance | Cost Multiplier |
|---|---|
| ±0.125mm | 1× |
| ±0.05mm | 1.3× |
| ±0.025mm | 2× |
| ±0.01mm | 3-5× |
Factor 4: Quantity (Economies of Scale)
Setup cost spreads across more parts:
| Quantity | Per-Part Cost (example) |
|---|---|
| 1 | (setup dominates) |
| 10 | |
| 50 | |
| 100 | |
| 500 | |
| 1,000 |
Factor 5: Surface Finish
| Finish | Added Cost |
|---|---|
| As-machined | Baseline |
| Bead blasted | +5-10% |
| Anodized (Type II) | +10-20% |
| Hard anodized (Type III) | +25-40% |
| Powder coated | +15-25% |
| Polished | +30-100% |
Factor 6: Setup Time
Complex parts requiring multiple setups (re-fixturing) drive up cost. A part machined in one setup can cost half as much as the same part requiring 4 setups.
Factor 7: Machine Type
| Machine | Hourly Rate (relative) |
|---|---|
| 3-axis mill | 1× |
| CNC lathe | 0.8× |
| 4-axis mill | 1.3× |
| 5-axis mill | 1.8× |
| Swiss-type lathe | 1.5× |
| EDM | 2.5×+ |
2. 7 Ways to Reduce CNC Machining Costs
1. Design for Fewer Setups
Design features accessible from fewer directions. A part that can be machined in 1-2 setups costs significantly less than one requiring 4+ setups.
2. Relax Non-Critical Tolerances
Only call out tight tolerances on features that actually need them — mating surfaces, bearing seats, locating pins. General tolerances for everything else.
3. Use Standard Tool Sizes
Design internal corner radii to match standard end mill diameters: 3mm, 4mm, 6mm, 8mm, 10mm, 12mm. Custom radii require special tools or 3D contouring.
4. Avoid Deep Features
- Pockets: keep depth < 4× tool diameter
- Holes: keep depth < 8× diameter (use standard drill lengths)
- Slots: keep depth < 3× width
5. Choose Cost-Effective Materials
- Aluminum 6061 over 7075 when strength allows
- 303 SS over 316 SS when corrosion requirements permit
- ABS over PEEK for non-critical plastic prototypes
6. Increase Quantity
Going from 1 to 10 parts can cut per-part cost by 60-70%. If you'll eventually need more, order them together.
7. Send Complete Information
Include tolerances, finishes, critical dimensions, and material specs upfront. RFQs with missing information require back-and-forth and often get padded quotes for safety.
3. Cost Estimation Formula
While exact pricing requires a quote, you can estimate:
`
Part Cost = (Material Cost × Waste Factor)
+ (Machine Hourly Rate × Machining Hours)
+ (Setup Cost ÷ Quantity)
+ Finishing Cost
+ Shipping
Where:
- Material Cost = Stock price × (1.5 to 3× for waste)
- Machine Rate = -120/hr depending on machine
- Machining Hours = Based on part complexity
- Setup Cost = -200 per setup
`
4. Real-World Cost Examples
Example A: Simple Aluminum Bracket
- Material: 6061-T6 aluminum
- Size: 100×50×20mm
- Tolerances: ±0.125mm
- Finish: As-machined
| Qty | Per-Part |
|---|---|
| 1 | |
| 10 | |
| 100 |
Example B: Complex Stainless Housing
- Material: 304 stainless steel
- Size: 200×150×80mm
- Tolerances: ±0.025mm critical features
- Finish: Bead blast + passivate
| Qty | Per-Part |
|---|---|
| 1 | |
| 10 | |
| 100 |
Example C: Titanium Aerospace Bracket
- Material: Ti-6Al-4V
- Size: 80×60×30mm
- Tolerances: ±0.01mm
- Finish: As-machined
| Qty | Per-Part |
|---|---|
| 1 | |
| 10 | |
| 100 |
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Published: July 2026 | Leland CNC — Precision Manufacturing Since 2009