Technical
CNC Machining Material Selection: Aluminum vs Stainless Steel vs Brass vs Titanium — Complete Comparison
Choose the wrong material and you’ll pay for it — in cost, in lead time, or in part failure. This guide compares the 4 most common CNC machining materials on every dimension that matters.
Material selection is the single decision that most impacts your part’s cost, performance, and manufacturability. Yet many engineers default to 6061 aluminum or 304 stainless without considering whether a different grade could deliver better results at lower cost. This comparison gives you the data to make an informed choice.
1. Head-to-Head Comparison
| Property | Aluminum 6061-T6 | Stainless Steel 304 | Brass C360 | Titanium Grade 5 |
|---|---|---|---|---|
| Tensile Strength | 310 MPa | 620 MPa ⭐ | 350 MPa | 950 MPa ⭐⭐ |
| Density | 2.7 g/cm³ (Lightest ⭐) | 8.0 g/cm³ | 8.5 g/cm³ | 4.4 g/cm³ |
| Machinability | ⭐⭐⭐⭐ Excellent | ⭐⭐⭐ Moderate | ⭐⭐⭐⭐⭐ Best ⭐ | ⭐⭐ Difficult |
| Material Cost/kg | $3–$5 (Cheapest ⭐) | $4–$7 | $5–$8 | $30–$45 (Most Expensive) |
| Corrosion Resistance | ⭐⭐⭐ Good (with anodizing) | ⭐⭐⭐⭐⭐ Excellent ⭐ | ⭐⭐⭐⭐ Very Good | ⭐⭐⭐⭐⭐ Excellent ⭐ |
| Weldability | ⭐⭐⭐⭐ Good (TIG/MIG) | ⭐⭐⭐⭐⭐ Excellent | ⭐⭐ Limited | ⭐ Poor (requires shielding) |
| Thermal Conductivity | 167 W/m·K ⭐⭐ | 16 W/m·K | 115 W/m·K | 7 W/m·K |
2. Aluminum 6061-T6 — The All-Rounder
Why choose it: Aluminum 6061 is the most commonly used aluminum alloy in CNC machining for good reason. It offers an excellent strength-to-weight ratio, machines quickly (reducing labor cost), accepts anodizing beautifully, and is the most affordable option. Best applications: Aerospace housings, bicycle components, electronic enclosures, automotive parts, general-purpose structural components. Limitations: Lower strength than steel or titanium, limited corrosion resistance without anodizing, cannot be used above ~150°C.
3. Stainless Steel 304 — Corrosion Champion
Why choose it: When you need excellent corrosion resistance combined with good mechanical properties, 304 stainless is the answer. It’s the standard for food processing, medical devices, marine hardware, and chemical equipment. Best applications: Food-grade equipment, medical instruments, marine fittings, chemical processing components, architectural hardware. Machining note: 304 work-hardens during cutting — it needs sharp tools, proper feeds/speeds, and adequate coolant. Expect 40–60% longer machining time vs. aluminum for the same geometry.
4. Brass C360 — The Machinist’s Dream
Why choose it: Brass C360 (free-machining brass) is the most machinable metal in existence — it cuts like butter and produces an excellent surface finish straight off the machine. It’s naturally corrosion-resistant and has antimicrobial properties. Best applications: Precision fittings, valves, pneumatic components, electrical connectors, decorative hardware. Limitations: Lower strength than steel, more expensive than aluminum, lead content in C360 (~3%) makes it unsuitable for potable water applications in some jurisdictions (use lead-free C69300 instead).
5. Titanium Grade 5 — The Premium Performer
Why choose it: Titanium Grade 5 (Ti-6Al-4V) offers the highest strength-to-weight ratio of any metal commonly used in machining. It’s biocompatible, corrosion-resistant to nearly everything (including seawater and chlorine), and performs at temperatures up to 400°C. Best applications: Aerospace structural components, medical implants, high-performance automotive, racing, marine. The cost reality: Titanium is 10× the material cost of aluminum, machines at 25–30% of the speed, and wears out tooling quickly. Expect a finished titanium part to cost 5–15× more than the same geometry in aluminum. Only use it when the properties justify the premium.
6. Quick Decision Matrix
| If You Need… | Choose | Alternative |
|---|---|---|
| Lowest cost, standard applications | Aluminum 6061 | Aluminum 5052 |
| High strength + low weight | Aluminum 7075 | Titanium Grade 5 |
| Best corrosion resistance | Stainless 316L | Titanium Grade 5 |
| Easiest to machine (complex parts) | Brass C360 | Aluminum 6061 |
| Food/medical grade | Stainless 304/316L | Titanium Grade 5 |
| High temperature (>200°C) | Stainless Steel | Titanium or Inconel |
| Heat dissipation (heat sinks) | Aluminum 6061 | Copper (if budget allows) |
Still Unsure Which Material to Use?
Our engineers can recommend the optimal material for your specific application — balancing cost, performance, and manufacturability. Free material consultation with every quote.
