01
Sharp edges shed the finish
Burrs and knife edges hold less coating than a flat face. The part looks fine at the bench, then the oxide wears through in the first week of field use. Deburring before finishing decides whether the black holds.
Aluminum Machining + Black Oxide
Aluminum Alloy CNC Processing with Black Oxidation
We machine aluminum parts to ±0.005 mm, then apply black oxide for corrosion resistance and a matte black surface. From one prototype to 10,000+ parts, with 100% inspection before shipment.
±0.005 mm tolerance6061 / 7075 / 5052Black oxide finishNo MOQ12-hour quote
127High-precision CNC machines
±0.005 mmAchievable tolerance
15 yearsAluminum machining experience
99.99%Qualification rate
Common Problems
Where aluminum parts fail before they ship
Most issues show up after machining, not during. Here are four we see often.
02
Color comes out blotchy
Alloy selection and surface prep drive color consistency. A batch mixed from 6061 and 6082, or parts with uneven as-machined texture, read as different shades under the same line light. Buyers notice that on an assembled panel.
03
Threads and bores change size
Any coating adds thickness. Tight-tolerance bores, press-fit holes and fine threads can close up after finishing, and the part no longer gauges. The fix belongs in the drawing review, not on the shop floor.
04
Tolerance drifts on long parts
Thin walls and long aluminum sections move with heat and clamping force. A 500 mm bracket can walk past ±0.005 mm between the first cut and the last, and the mating plate will not sit flat. Rigid fixturing and in-process checks catch it.
Our Approach
Machining and finishing under one roof
Keep the cut and the coating in the same process so dimensions and color stay predictable.
Machining
Aluminum alloy CNC processing built around the part, not the machine
We run 127 high-precision CNC machines, including 16 simultaneous 5-axis centers, 12 four-axis mills and 27 three-axis machines. That range lets us pick the setup that holds the feature instead of forcing every part onto one spindle.
For aluminum we routinely cut 6061, 6061-T6, 2024, 5052, 5083, 6063, 6082, 7075 and ADC12. Maximum processing size reaches 4,000 mm, with a Ø400 mm rotary table for parts that need multi-face work in one setup.
- 1Tight tolerance±0.005 mm on critical features, verified before the part leaves the machine.
- 2Finish controlAs-machined Ra 1.6–3.2 μm, high finish Ra 0.8–1.6 μm, fine finish Ra 0.2–0.8 μm.
- 3Setup choice5-axis, 4-axis or mill-turn, matched to the geometry and the quantity.
Finishing
Black oxide applied after a clean, uniform machined surface
Black oxide is a conversion coating, not a paint. It reacts with the aluminum surface to form a matte black layer that resists handling marks and light corrosion. It does not build a thick film, so a well-prepared part keeps its dimensions.
The result depends on what happens before the tank. We deburr, tumble or bead blast first, then run the oxide. Where the drawing allows, we mask threads and bores so gauges still pass. Laser marking comes after, with a minimum character height of 1.5 mm.
- 1Uniform colorConsistent prep gives a consistent matte black across the batch.
- 2Dimension safeThreads and bores stay in tolerance when masking is planned at drawing review.
- 3Pairs with other workAnodizing, plating, powder coating, blasting and polishing are all in-house.
Selection Guide
When black oxide fits, and when it does not
Use the part function to pick the finish, not the color alone.
| Part condition | Black oxide | Better alternative |
|---|---|---|
| Indoor housing, matte black look | Good fit | Anodizing if color matching matters |
| Heavy abrasion on edges | Wears through | Hardcoat anodizing |
| Tight bores and fine threads | Needs masking | Mask or skip the coating |
| Salt spray or marine exposure | Limited protection | Anodizing plus sealing |
| Electrical contact surfaces | Insulating effect | Conductive anodizing or bare |
| Cosmetic panel, color critical | Shade varies by alloy | Colour anodizing on one alloy lot |
Services
What we can take on
One shop for the cut, the finish and the inspection.
01
5-Axis CNC Machining
16 simultaneous 5-axis centers for complex aluminum geometry in fewer setups.
02
3 & 4-Axis CNC Machining
27 three-axis and 12 four-axis machines for prismatic parts and higher volumes.
03
CNC Milling & Turning
16 mill-turn centers handle shafts, housings and parts with both features.
04
Rapid Prototyping
Prototype aluminum parts before tooling, with DFM feedback inside 12 hours.
05
Part Surface Finishing
Black oxide, anodizing, plating, powder coating, blasting and laser marking.
06
Sheet Metal Fabrication
Enclosures and chassis in aluminum, finished to match machined components.
Capability
Aluminum machining and finishing scope
Numbers from our three plants in Dongguan and Singapore.
| Item | Range |
|---|---|
| Aluminum grades | 6061, 2024, 5052, 5083, 6063, 6082, 7075, ADC12 |
| Tolerance | ±0.005 mm (±0.0002 in) |
| Surface finish | Ra 0.2–3.2 μm depending on operation |
| Maximum part size | 4,000 mm |
| Machine travel | 4,000 × 400 × 150 mm; 750 × 1,150 × 550 mm; 500 × 500 × 450 mm |
| Rotary table | Ø400 mm |
| Order quantity | No minimum, from 1 prototype to 10,000+ parts |
| Quote turnaround | Quotation and free DFM analysis within 12 hours |
Why GreatLight
Reasons engineers keep sending aluminum work here
Fifteen years of aluminum, and the numbers that back it up.
15Y
Aluminum since 2011
Founded in 2011, we have machined aluminum across three wholly-owned plants covering 7,600 m².
±0.005
Tolerance held, not promised
Critical features are checked against ±0.005 mm before shipment, with reports on request.
127
Machines to match the job
5-axis, 4-axis, 3-axis and mill-turn capacity means the setup follows the part.
12H
Quote and DFM in 12 hours
Send a drawing and we return pricing plus manufacturability notes the same day.
4
Certifications on file
ISO 9001:2015, IATF 16949:2016, ISO 13485:2016 and ISO 27001:2022.
MTO
No minimum order quantity
One prototype or a 10,000-part run, both go through the same inspection route.
7,600 m²Manufacturing space
150Technicians on staff
3Wholly-owned plants
<2%Historical late-delivery rate
Applications
Where these parts end up
Automotive & EV
Engine and drivetrain aluminum parts where fit and repeatability drive the build.
- ±0.005 mm
- IATF 16949
Industrial Machinery
Control chassis and brackets that need a matte black finish and clean edges.
- Black oxide
- Deburred edges
Robotics & Automation
Lightweight aluminum links and fixtures, machined in small batches.
- No MOQ
- 3–5 day ship
Electronics
Housings and heat-sink bodies where flatness and finish both matter.
- Ra 0.8–1.6 μm
- 100% inspection
FAQs
Questions we get about aluminum and black oxide
Does black oxide change the part dimensions?
It is a conversion coating, so the film is thin compared with plating or paint. On a flat face the change is usually not measurable with standard shop gauges.
The risk sits in tight bores, press fits and fine threads, where any added thickness matters. Tell us which features are critical and we will mask them or leave stock for the coating.
Which aluminum grades take black oxide well?
The 6000 series, including 6061, 6063 and 6082, gives the most even result. The 5000 series like 5052 and 5083 also coats cleanly.
High-copper grades such as 2024 and 7075 can show more variation in shade. If color consistency across a batch is critical, keep the parts on one alloy and one lot.
Can you machine and finish aluminum in the same order?
Yes. Machining, deburring, black oxide and laser marking run as one route, which removes the back-and-forth between vendors.
It also means the finish is planned around the geometry rather than applied afterwards. Threads, bores and datum faces are handled at drawing review.
What surface finish should I specify before black oxide?
Most parts are finished as-machined at Ra 1.6–3.2 μm, which gives a uniform matte black. If you want a smoother look, ask for Ra 0.8–1.6 μm.
A finer finish than Ra 0.2–0.8 μm is rarely needed for appearance, and it adds cost. The coating follows the texture underneath, so decide the texture first.
Is black oxide enough for outdoor or marine use?
It resists handling marks and light indoor corrosion. It is not a substitute for anodizing in salt spray or constant moisture.
For outdoor hardware, hardcoat or colour anodizing holds up better. We will say so rather than sell you a finish that fails in service.
How small a batch will you run?
There is no minimum order quantity. A single prototype goes through the same inspection route as a production run.
Production can start within 24 hours of an approved order, and parts typically ship in 3–5 days. Larger runs are quoted with a schedule up front.
What files do you need for a quote?
Send a 3D model plus a 2D drawing with tolerances, material and finish callouts. STEP and PDF cover most jobs.
If you only have a model, we will quote against it and flag the features that need a tolerance call before cutting. Uploads stay confidential, and an NDA is available on request.
Can you mask threads and bores before coating?
Yes, masking is standard practice for us when the drawing identifies critical features.
We mark the mask areas during DFM review so you can confirm before the run. That prevents a finished part from failing a gauge check.
Send your aluminum part for machining and black oxide
Upload a STEP file and drawing. You get a quote, DFM notes and a finish plan within 12 hours.
12-hour quote100% inspectionNo minimum order quantityNDA on request
