Aluminium Turned Parts
6061-T6 / 7075-T6 · anodizing and hard anodizing · Ø1–20 mm · ±0.005 mm
CHX Metal turns aluminium parts in 6061-T6 and 7075-T6 on 70 Tsugami Swiss-type lathes, bar Ø1–20 mm, held to ±0.005 mm, with anodizing and hard anodizing in 3–7 days. Monthly capacity is 5 million pieces; quoting takes 24 hours.
Aluminium is the easiest material to cut and the hardest to hold a tolerance on, because it moves. A part that measures perfect on the machine can be out of tolerance an hour later once it reaches room temperature and the internal stress redistributes. Everything below follows from that one fact.
Grade selection
| Specification | Capability |
|---|---|
| 6061-T6 | General purpose, good machinability and corrosion resistance, welds and anodizes well |
| 7075-T6 | High strength, poorer corrosion resistance, needs a proper anodize or chromate to survive outdoors |
| 6082-T6 | European equivalent of 6061 with slightly higher strength; common for EU drawings |
| 2011 / 2017 | Free-machining grades for high-volume small parts where finish is less critical |
| 2024-T4 | Aerospace-grade strength with poor corrosion resistance; requires protection |
The most common mistake is specifying 7075 because it sounds stronger. If the part is exposed to moisture and gets a clear anodize, 7075 will show corrosion at the edges inside a season. 6061 with the same finish will not.
Why aluminium parts move after machining
Extruded and rolled bar carries residual stress. Machining removes material from one side of that stress field and the part relaxes — a bore goes oval, a flange goes out of flat, a thin wall springs. The effect grows with the amount of material removed and with wall thinness.
Three controls address it: rough machine and let the part rest, finish in a second setup; use stress-relieved stock for thin parts; and keep the finishing cut light with a sharp tool so the surface is cut rather than smeared. A supplier without these steps will pass the first article and fail the production run.
Temperature is part of the tolerance
Aluminium expands about 23 µm per metre per °C — twenty-three times more than steel. On a 100 mm feature, a 5 °C difference between machine and inspection room is 11 µm, which is more than the whole ±0.005 mm band. A ±0.005 mm call on aluminium therefore has to name the measurement temperature, or it is not a specification.
We gauge at 20 °C and record it. If your drawing does not state a temperature, the DFM note will ask for one.
Anodizing: thickness budget and colour
- Type II sulphuric anodize grows about 50% into and 50% out of the surface, so a 15 µm coating moves a dimension by roughly 7 µm per side.
- Type III hard anodize is thicker and harder — excellent for wear surfaces, but it darkens colour and reduces fatigue life.
- Colour consistency varies with alloy and batch; 6061 anodizes more predictably than 7075.
- Masking threads and bores is a separate operation and should be called out on the drawing, not discovered at inspection.
Typical aluminium turned parts
Optical and photonics housings, heat-sink bases, connector shells, camera mounts, drone and robotics structural pins, sensor bodies, audio knobs, liquid-cooling connectors and manifolds. Bar Ø1–20 mm on the Swiss cell; up to Ø300 mm chuck work on the CNC lathes.
Related capabilities
CNC turned parts manufacturer · Precision aluminium CNC · Aluminium housing CNC · Surface treatment · Brass turned parts · Stainless steel turned parts · CNC machining China
Request a quote
Send drawing (STEP / PDF / DXF) with material, tolerance and annual volume to mc@chxmetal.com. DFM feedback and a price within 24 hours, NDA on request.
Get a CNC quote · Contact CHX Metal · Supplier profile & certificates
Frequently asked questions
Should I use 6061 or 7075 for turned parts?
6061-T6 unless you need the extra strength of 7075. 7075 machines well but corrodes more readily and its anodized colour is less consistent, so it needs a deliberate finish decision.
Why do my aluminium parts measure out of tolerance after shipping?
Residual stress release and thermal expansion. Thin walls relax after machining and aluminium moves about 23 µm per metre per °C, so a part measured warm reads differently from one measured at 20 °C.
How much does anodizing change the dimension?
A 15 µm Type II coating grows roughly 7 µm per side because half the coating grows into the surface. Pre-plate dimensions must be set accordingly, and threads or bores that must stay clear need masking.
Can you hold ±0.005 mm on aluminium?
Yes, with the measurement temperature stated. We gauge at 20 °C and record it; without a stated temperature the tolerance band is smaller than the thermal drift on a 100 mm feature.
What is the MOQ and lead time?
One piece, no MOQ gate. Prototypes in 3 to 7 days, production in 7 to 15 days, anodizing adds 3 to 7 days.