Aluminium CNC machining
Aluminium cuts easily. The difficulty in an aluminium part is not cutting it but holding it to size — thin walls deflect, released stress bends the part, long chips scratch the surface. A light bracket and a precision housing are made from the same material but not in the same way.
Where the difficulty actually sits
- Deflection and chatterOn a thin wall the cutting force pushes the wall away; when the tool passes, the wall springs back and the size is wrong. Once chatter starts it leaves marks on the surface. The answer is not simply slowing down but rebuilding the depth of cut and the workholding.
- Residual stress and distortionPlate and block stock carry internal stress from rolling and heat treatment. As material is removed that stress is released and the part bends on its own. Where a large volume is removed, stress relief between roughing and finishing may be needed.
- Chip evacuationAluminium produces long, stringy chips. Chips gathering in a pocket wrap around the tool, scratch the surface and keep heat in the part. High-pressure coolant and the right cutting direction solve it.
- Burrs and finishA soft material burrs readily. Deburring is part of the process; if the drawing does not state the edge condition, we ask before production.
6061 or 7075?
Both are common, but for different jobs. The choice sits between the strength you need and what it costs in money and machining time.
| 6061-T6 | 7075-T6 | |
|---|---|---|
| Main alloying element | Magnesium and silicon | Zinc (5.6–6.1%) |
| Tensile strength | ≈ 310 MPa | 510 – 540 MPa |
| Yield strength | ≈ 270 MPa | 430 – 480 MPa |
| Density | 2.70 g/cm³ | 2.81 g/cm³ |
| Machinability | Easier; allows higher cutting speeds | Harder; needs lower feeds and careful cooling |
| Welding | Weldable | Not suited to welding |
| Corrosion resistance | Better; takes anodising well | Lower; prone to stress corrosion |
| Typical use | Housings, brackets, enclosures, general machine parts | High-strength aerospace and sporting equipment parts |
The practical conclusion: if the part does not genuinely need the strength of 7075, specify 6061. 7075 costs more and takes noticeably longer on similar geometry, and both show up in the price. Conversely, where a thin load-bearing part is beyond 6061, 7075 is the right call and saving there puts the part at risk.
What five axes give you in aluminium
Aluminium parts run on our DMG Mori DMU 50 and DMU 70 five-axis machining centres. Five axes buy two things here. First, a multi-face part is finished in one setup; every additional setup would add a positional error and a deflection risk, and that sum disappears. Second, the tool approaches the part at a better angle, which means working with a shorter tool — and a short tool deflects less and leaves a better surface.
Prismatic and series aluminium parts go to our DMG Mori DMC 635 vertical machining centre; small-diameter turned parts to our Star sliding headstock lathes. Inspection is in-house: a COORD3 ARES CMM with a Renishaw PH20 probe.
What a quote needs
- A drawing or 3D model — STEP preferred, with a 2D drawing for tolerances.
- Alloy and temper — 6061-T6, 7075-T6 or another; if unsure, tell us what load the part carries.
- Quantity and lead time — a single prototype and a repeating batch are not priced the same way.
- Surface treatment and edge condition — anodising, paint, deburring, inspection report.
We review the drawing for manufacturability and quote it. If we see a thin wall, a deep pocket or an unnecessarily tight tolerance, we say where it can be eased without affecting how the part works.
- aluminium CNC machining
- 5-axis milling
- 6061
- 7075
- thin wall
- anodising
- Ankara Ostim
Frequently asked questions
Should I choose 6061 or 7075?
If the part does not need high strength, 6061 is enough: it is cheaper, machines faster, can be welded and takes anodising better. 7075 is roughly twice as strong in tension but cannot be welded, is more exposed to corrosion and takes noticeably longer on similar geometry.
Why does an aluminium part distort?
Plate and block stock carry internal stress from rolling and heat treatment. As material is removed that stress is released and the part bends. Where a lot of material comes off, stress relief between roughing and finishing — or distributing the passes symmetrically — is needed.
Can you machine thin-walled aluminium parts?
Yes, but the fixture and the pass strategy become the real work. On a thin wall the problem is not the cutting force itself but the wall deflecting under it and springing back. On parts like these the process should be planned together from the start.
Do you handle anodising?
Anodising, plating and painting are managed as special processes; the work is followed before the part ships from us. Remember that anodising adds thickness — if there are critical dimensions, the drawing must state whether they apply before or after anodising.
Do you provide inspection reports?
Yes. Inspection is in-house on a COORD3 ARES CMM with a Renishaw PH20 probe. On request the inspection report, material certificate and declaration of conformity are sent with the part.
Send us your technical drawing and quantity; we will prepare your quote with a manufacturability review.
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