Choosing the right aluminum for CNC machining is seriously important. Pick the wrong one and you’re either wasting money or ending up with parts that don’t work. We’ve worked with a lot of clients at our company and learned quite a few lessons the hard way.
Let me just give you the bottom line first: for 90% of projects, just go with 6061.
Three Main Aluminum Alloys: 6061, 7075, 5052
There are dozens of aluminum alloys out there, but for CNC machining, these three are the ones you’ll actually use: 6061, 7075, 5052. In the projects we handle, 90% use 6061, and the remaining 10% are 7075 and 5052.
6061: The Most Versatile Choice
If you’re not sure which one to pick, just go with 6061.
6061 is the most common aluminum out there, and 90% of our orders use it. It has so many advantages:
Easy to machine: Cuts fast, minimal tool wear, short cycle times
Good corrosion resistance: Fine for most indoor and outdoor environments
Weldable: Can be welded and heat-treated afterward to restore strength
Inexpensive: Most affordable option
Anodizes well: Can do pretty much any color you want
We’ve made all kinds of 6061 parts: brackets, bike frames, electronic enclosures, automotive parts, machine components. Honestly, for most situations, 6061 is plenty.
I had a client once who wanted to use 7075 from the start, thinking more expensive must be better. I asked him what he needed it for, and he said it was just a regular enclosure. I told him, just use 6061 then, save half the money. He listened to my advice and actually came back later to thank me, saying I helped him save a lot of budget.
6061 Basic Specs:
Tensile strength: ~310 MPa
Yield strength: ~276 MPa
7075: Only If You Really Need High Strength
7075 is aerospace-grade, close to steel in strength but only a third of the weight. Tensile strength can reach 572 MPa, almost double that of 6061.
But 7075 has some issues:
Expensive: 30-50% more than 6061 for the material alone
Harder to machine: Higher hardness means slower cutting, more tool wear
Poor corrosion resistance: Must do surface treatment
Not weldable: Welding ruins it
So 7075 is only for these scenarios: aerospace components, drone frames, racing parts, military equipment. We’ve done some 7075 parts, but only when the client explicitly required high strength.
Honestly, I’ve met several clients who insisted on 7075 at first, thinking “most expensive is best.” After I analyzed it for them, they realized they didn’t need that kind of strength, and switched to 6061, saving a lot of money. So unless you really need ultra-high strength (this depends on the actual loading situation), don’t pick 7075.
5052: Choose This for Corrosive Environments
5052’s standout advantage is corrosion resistance, especially to saltwater and chemicals, better than both 6061 and 7075.
Other features:
Weldable, minimal strength loss after welding
Easy to form (sheet metal, stamping)
Good fatigue resistance
But it’s not as strong, tensile strength is only 228 MPa, and it’s soft, so machining is a bit tricky.
5052 is suitable for: marine components, fuel tanks, outdoor equipment, sheet metal parts. We did marine equipment for one client that had to use 5052, otherwise it would corrode quickly at sea.
A Simple Selection Method
Still not sure? Here’s a simple decision tree:
Will your part be exposed to saltwater, chemicals, or harsh corrosive environments?
Yes → Use 5052
No → Check next question
Does your part need to handle extremely high loads or impacts? (e.g., aerospace, racing)
Yes → Use 7075
No → Check next question
Do you need to weld it?
Yes → 5052 or 6061 (5052 welds better)
No → Just use 6061
Cost Comparison (Real Experience)
Material cost (relative):
6061: 1
5052: ~1.2
7075: 1.5-2.0
Machining cost (relative):
6061: 1
5052: 1.2-1.5 (a bit trickier to machine)
7075: 1.5-2.0 (expensive and slow)
So when we quote clients, 7075 parts are usually 50-100% more expensive than 6061. If you have budget constraints, or the strength requirements aren’t that high, there’s really no need to go with 7075.
Our Process
Honestly, a lot of clients don’t really understand the CNC machining process at first and think it’s pretty complicated. Let me walk you through it – it’s actually just a few steps.
Step 1: Receive Drawings
Clients usually send us CAD drawings or 3D models. Our team will look them over carefully, checking for technical requirements, tolerances, surface treatments, and such. Sometimes there are issues with the drawings, and we’ll communicate with the client to avoid problems later.
I had a client once where the dimension markings on the drawing weren’t quite reasonable. We helped optimize it a bit – guaranteed function while reducing machining difficulty. The client was pretty happy about that.
Step 2: Quote Confirmation
After reviewing the drawings, we give the client a quote. The quote includes material costs, machining costs, surface treatment costs, and such.
Honestly, some clients think the price is a bit high at first. I usually explain it to them: CNC machining isn’t as cheap as 3D printing, but the precision and quality are definitely better. If you’re after precision and durability, CNC is worth it.
Step 3: Programming and Fixture Design
Once the quote is confirmed, we start programming. This step is pretty critical – directly affects machining efficiency and part quality.
Our team has a master programmer with over 10 years of CNC programming experience. He designs the most appropriate machining paths and fixtures based on the part’s shape and material. Good programming can reduce machining time by 20-30% and also better guarantee quality.
Step 4: CNC Machining
After programming, the actual machining starts. This part is basically automated, but our technicians monitor the whole process to make sure everything’s fine.
Aluminum machining generates chips and heat, so we need cutting fluid. The choice of cutting fluid is also quite important – we generally use environmentally friendly ones, better for the environment and less irritating for workers.
Step 5: Quality Inspection
After machining is complete, we do quality inspection. Depending on the part’s precision requirements, we use calipers, micrometers, CMMs, and other equipment for measurement.
Our standard is: even if the client’s requirements aren’t that high, we still try our best to do it well. After all, reputation is built order by order.
Step 6: Surface Treatment (Optional)
If the client needs surface treatment, we’ll arrange it. Common ones are anodizing, sandblasting, plating, and such.
Anodizing is the most common surface treatment for aluminum – improves corrosion resistance and can add color. But I should mention: anodizing slightly changes part dimensions, increasing by about 0.01-0.02mm. If you have high dimensional accuracy requirements, this needs to be considered.
Step 7: Shipping
Finally, packaging and shipping. We use foam, bubble wrap, and such for good packaging to ensure no damage during transport.
I have a client in Europe, so every shipment goes by sea. At first I was worried about transport issues, but with good packaging there’s generally no problem. We’ve been working together for several years now.
Custom Services
Speaking of customization, we do quite a bit of this.
Every client’s needs are different – some need mass production, some just a few samples; some need complex curved surfaces, some just simple blocks. We’ve done it all.
Sample Orders
If you just want to make some samples to try, that’s totally fine. We’ve done many small batch orders, sometimes just 1-2 parts. Even though the unit price is a bit higher, it helps you verify design and material feasibility.
I had a client who made 10 samples at first, and after testing found that 6061 didn’t meet requirements, so they switched to 7075. Although they spent some extra money, it avoided rework after mass production, which actually saved money.
Mass Production
If the samples are fine and you want mass production, we can do that too. The advantage of mass production is that unit costs come down, since some fixed costs are spread across more parts.
But honestly, mass production isn’t just copying. We usually do first piece inspection to ensure everything’s good before continuing. We also do spot checks during production to avoid batch issues.
Special Requirements
Some clients have special requirements, like:
Extremely high precision (within ±0.01mm)
Special shapes (complex curved surfaces, thin wall structures)
Special surface treatments (matte, mirror finish, specific colors)
We can do all of these, but there might be extra charges. I usually tell clients this upfront to avoid disagreements later.
I once had a client who wanted extremely thin aluminum parts, the thinnest part being only 0.5mm. At first I was a bit worried, afraid it would deform during machining. Later I studied it with our master craftsman, adjusted the fixtures and machining parameters, and the final result was pretty satisfactory. The client even sent a thank you email saying our craftsmanship level is high.
So whatever your needs, just tell us. We can’t do everything, but at least we’ll assess it seriously and give you a reliable answer.
Our Recommendations
Simply put:
Most cases: 6061 (versatile, cheap, easy to machine)
Need ultra-high strength: 7075 (aerospace, racing)
Corrosive environments: 5052 (marine, chemicals)
Of course, every project is different. If you’re not sure which one to choose, you can ask our team to help analyze. We’ve worked with clients from various industries and should be able to give you a pretty reliable suggestion.
