Choosing the Right Aluminum Alloy
By Adam Kemici | Ziqual
Aluminum is the go-to material when you want light weight, decent strength, and corrosion resistance—but picking the right aluminum alloy isn’t as straightforward as it sounds. The options are wide, and the differences between them can matter a lot depending on how you're machining, welding, or using the part.
At Ziqual, we see aluminum parts come through every week—from consumer enclosures to aerospace components—and I’ve had plenty of conversations with customers who ask, “Should I just go with 6061?” Sometimes that’s the right answer. Sometimes it’s not.
Let’s walk through the key factors and common alloys to help you make a decision that fits both your performance needs and your budget.
Why Aluminum?
Compared to steel, aluminum is much lighter—about one-third the weight. It resists corrosion naturally (thanks to that thin oxide layer), conducts heat and electricity well, and is generally easy to machine. It’s also recyclable and widely available.
But not all aluminum behaves the same. And some alloys that sound great on paper can be a pain to weld or machine in real life.
Start With These Questions
Before choosing an alloy, ask:
- Is weight a critical factor?
- Does the part need to be welded or anodized?
- Will it see stress or repeated loading?
- How important is surface finish or appearance?
- Are we prototyping or going to production?
These questions can narrow things down fast.
Aluminum Alloy Categories—What to Know
There are two broad groups:
🔸 Wrought Alloys (4-digit series like 6061, 7075, etc.)
Shaped by rolling, extrusion, or forging. Most parts you machine or bend come from wrought alloys.
🔸 Cast Alloys (like A356)
Poured into molds. Used when you need complex shapes, less machining.
Note: This article focuses on wrought aluminum, which is what we see most often in CNC parts.
Common Aluminum Alloys — Pros, Cons, and Real-World Use
🔹 6061 Aluminum (T6 temper is most common)
If you’re looking for a good all-around alloy, this is it. It’s strong, corrosion-resistant, weldable, and machines fairly well. It anodizes okay (not great).
Use Cases: Structural parts, brackets, enclosures, fixtures
Caveat: It’s not the strongest, and the finish after anodizing can be a little dull or grayish.
🔹 7075 Aluminum
This is your high-performance alloy. Much stronger than 6061—almost like mild steel in terms of strength—but it’s not easy to weld, and corrosion resistance is lower.
Use Cases: Aerospace, high-load parts, mountain bike components, firearms
Caveat: More expensive, less forgiving, and not great for welding.
🔹 5052 Aluminum
Excellent corrosion resistance and very good formability. Common in sheet metal parts and marine applications.
Use Cases: Boat panels, electrical enclosures, tanks
Caveat: Doesn’t machine as nicely as 6061, and can be gummy without sharp tools.
🔹 2024 Aluminum
Used heavily in aerospace—very high strength-to-weight ratio. But it's more prone to corrosion than other alloys and doesn’t weld well.
Use Cases: Aircraft skins, fuselage parts, race car panels
Caveat: Needs protective coating or anodizing to survive long-term.
🔹 MIC 6 / Cast Tooling Plate
This one’s a bit different—it’s a cast, stress-relieved plate that’s incredibly flat and dimensionally stable.
Use Cases: CNC fixtures, tooling plates, inspection surfaces
Caveat: Not meant for structural parts. It’s about flatness and precision, not strength.
🛠️ Shop Story: When Not to Use 7075
A startup once came to us with an aluminum camera gimbal housing. Their engineer had spec’d 7075 for “maximum strength.” It sounded good, but when we ran it through CAM, we saw it would require extra tool changes, slower feeds, and special fixturing—just to make something that didn’t actually need 7075.
We switched it to 6061, saved them 40% on machining time, and the part was still more than strong enough. Right material, right place.
What to Watch Out For
- Welding: Only some aluminum alloys weld easily (like 6061 and 5052). Alloys like 7075 and 2024 will crack unless you know what you’re doing.
- Machinability: 6061 is forgiving. 5052 can be gummy. 7075 is hard but cuts cleanly.
- Corrosion Resistance: 5052 > 6061 > 7075 > 2024.
- Anodizing: Alloys anodize differently. 6061 gives a decent result. 7075 can come out blotchy unless you prep it well.
Tips for Picking the Right Aluminum Alloy
✅ Start with 6061 unless there’s a reason not to. It’s the most versatile for a reason.
✅ Go stronger with 7075 only if absolutely needed.
✅ Use 5052 for sheet metal or marine.
✅ Choose MIC 6 for precision flat parts.
✅ Talk to your machinist. Some alloys look great on paper but are expensive to work with.
Final Thoughts
Choosing the right aluminum alloy isn’t about memorizing datasheets—it’s about understanding your part’s role in the bigger picture. What does it need to do? What will it experience? And how will it be made?
At Ziqual, we’ve seen parts fail because someone picked the wrong alloy, or blow past their budget using one that was overkill. The sweet spot is where performance, cost, and manufacturability meet.
If you’re designing something and aren’t sure which alloy to use, reach out. We’ll help you think it through—no pressure.