I run a small job shop with a manual lathe, a Bridgeport, and a Tormach CNC. Choosing the right aluminum alloy makes or breaks a part. To settle some shop debates I machined the same simple fixture out of five common alloys using identical tooling and feeds. Here’s how they actually behaved.
Comparison Table
| Alloy | Machinability | Tensile Strength | Best For |
|---|---|---|---|
| 6061-T6 Aluminum | Good | 45 ksi | General purpose |
| 7075-T6 Aluminum | Excellent | 83 ksi | Aerospace parts |
| 2024-T3 Aluminum | Excellent | 70 ksi | Aircraft skin |
| 5052-H32 Aluminum | Fair | 33 ksi | Sheet metal forming |
| Mic-6 Cast Aluminum | Excellent | 25 ksi | Fixtures and tooling plates |
6061-T6 Aluminum
The default for a reason. Decent strength, anodizes well, and chips nicely if your feeds and speeds are right. Surface finish on the lathe is acceptable but can be gummy without proper coolant.
7075-T6 Aluminum
My favorite to machine. It chips clean and shorter than 6061, takes a beautiful finish off carbide, and holds tighter tolerance after heat treat. Costs more and corrodes faster, so anodize for outdoor parts.
2024-T3 Aluminum
Old aerospace standby. Cuts almost as nicely as 7075 and has slightly more fatigue resistance. Doesn’t anodize cleanly so it’s almost always alclad or painted.
5052-H32 Aluminum
Soft and gummy compared to the others, but unmatched for sheet bending. I use it when a part starts as a CNC operation and ends in a press brake. Sharp tools and high RPM help with finish.
Mic-6 Cast Aluminum
Stress-relieved cast plate that stays flat after cuts. The killer feature is dimensional stability; I use it for jig and fixture plates that need to stay accurate over years. Cuts like butter.
What Matters Most
Match alloy to function, not preference. Strength alloys like 7075 chew tool life faster but pay back in part performance. Soft alloys like 5052 form well but won’t hold thread tolerances. Heat treatment temper matters too: a T6 versus T0 of the same alloy machines completely differently.
My Setup
I keep 6061 for the bulk of customer parts, 7075 for performance or fatigue-loaded jobs, and Mic-6 for tooling plates. Coolant flood for everything because dry-cut aluminum builds up on the cutting edge fast.
Common Mistakes
People run aluminum like steel and complain about gummy finishes. Aluminum likes high SFM and sharp tools. Another mistake is choosing 7075 for outdoor parts and discovering it corrodes within months. Anodize it or pick 6061.
Final Recommendation
If your shop only stocks one alloy, make it 6061-T6. If you can stock two, add 7075-T6 for high-stress parts. For toolmakers and fixture builders, Mic-6 is a quiet game-changer that I wish I’d discovered years earlier.
Frequently asked questions
What is the easiest aluminum to machine?+
6061-T6 is the standard easy machining alloy. 2024 and 7075 cut even better but cost more and don't anodize as cleanly.
Can I weld machinable aluminum?+
Yes for 6061 and 5052. Avoid welding 2024 and 7075 because they crack and lose strength in the heat-affected zone.