01
You re-chuck the part four times
Every extra setup adds a datum shift. Bolt patterns that should sit 0.01 mm apart land 0.05 mm out, and the actuator flange will not seat without reaming holes on site.
Robotics & Automation
5 Axis CNC Machined AI Robot Complex Joint Parts
Joint housings, wrist links and brackets cut from aluminum and titanium in one setup. We hold ±0.005 mm across five faces so actuators, bearings and encoders drop in without hand fitting.
16 five-axis centers±0.005 mmOne-setup 5-face workNo minimum order12-hour quote100% inspection
16Simultaneous 5-axis centers
±0.005 mmAchievable tolerance
4,000 mmMaximum part size
ISO 9001:2015Quality system in place
Where joints go wrong
Four problems that show up on the assembly bench
Most of these trace back to how the part was set up, not to the drawing.
02
Bearing bores come in oval
Thin walls relax when the clamps come off. A bore that measured round on the machine reads 0.02 mm out of round after anodizing, so the bearing either rattles or will not slide in.
03
Encoder feedback will not settle
Housing faces that are not square to the axis tilt the encoder disc. The arm hunts at low speed, and tuning the loop cannot fix a geometry error. Flatness and perpendicularity have to be cut in.
04
Weight creeps up on the arm
Oversized bosses and thick flanges add mass at the wrist, so the motor works harder and cycle time slips. Designers need wall sections near 1.5 mm kept stable, not solid blocks.
How we machine them
One setup, five faces, one datum
The joint is only as good as the surfaces that reference each other.
Setup strategy
Five faces cut without re-chucking
A robot joint has features on every side: a motor mount, a bearing bore, a cross-roller seat, cable passages, mounting ears. On a three-axis machine that means four or five setups and a fresh datum each time. On our simultaneous five-axis centers the part stays in one fixture, so the bore and the bolt circle keep their relationship through the whole cycle.
We plan the setup from the datum scheme, not from what is easy to clamp. If your drawing calls out the bearing bore as datum A and the flange face as datum B, those two surfaces come off the same spindle in the same operation. Everything else is measured against them.
- 1One fixtureTrunnion or dovetail hold, no re-chucking between faces.
- 2Datum-to-datumBore and flange cut in the same operation.
- 3Access for long toolsUndercuts and deep pockets reached at an angle.
Geometry control
Holding round bores in thin walls
Joint housings are thin by design. Weight at the wrist costs torque, so walls run 1.5 mm to 3 mm and the bore sits close to the outside skin. Clamp pressure deforms that wall while cutting, and the part springs back after the vise opens.
We rough with extra stock, let the part cool, then finish with light radial passes and low clamping force. Bores are checked for roundness and taper, not just diameter. When anodizing or hardcoat comes after machining, we mask and re-check the critical bore, because a coating can move a tight fit by more than the tolerance you allowed.
- 1Rough then relaxStress relieved before the finish pass.
- 2Roundness checkedNot only the diameter reading.
- 3Coating awareMasking and re-check after hardcoat.
Selection guide
Which parts belong on a five-axis machine
Not every joint component needs five axes. This is how we split the work.
| Part type | Best process | Why |
|---|---|---|
| Joint housing, 3+ faces | 5-axis, one setup | Datum stack stays closed |
| Wrist link, long and slim | 5-axis with tailstock | Deflection controlled along length |
| Cross-roller bearing seat | 5-axis, finish in place | Roundness and squareness together |
| Simple end cap, one face | 3-axis mill | Five axes add cost, not accuracy |
| Turned shaft with cross holes | Mill-turn center | Turning and milling in one cycle |
| Prototype bracket, 1-5 pcs | 5-axis, no tooling | Design changes absorbed in CAM |
What we run
Machining and finishing under one roof
Six capabilities that cover a robot joint from raw stock to coated part.
01
5 Axis CNC Machining
Simultaneous five-axis milling for joint housings, wrists and brackets. 16 centers, up to 4,000 mm of travel.
02
4 Axis and 3 Axis Milling
For single-face plates and covers where five axes would only add cycle time.
03
CNC Milling and Turning
Mill-turn centers handle turned shafts with cross holes and flats in one cycle.
04
Rapid Prototyping
One-off joints for fit checks and kinematics tests before the design freezes.
05
Surface Finishing
Anodizing, hardcoat, electroless nickel, bead blasting and laser marking.
06
Inspection and Reporting
100% inspection before shipment, with dimensional reports on request.
Scope
Materials, tolerance and finishing options
Numbers below are what our process holds in normal production.
| Item | Range | Notes |
|---|---|---|
| Tolerance | ±0.005 mm | ±0.0002 in on critical fits |
| Surface finish | Ra 0.2–0.8 μm | Ra 0.8–1.6 μm standard |
| Aluminum | 6061, 7075, 2024, 6082 | Lightweight joint bodies |
| Titanium | TC4 (Ti-6Al-4V), TA2 | High-load wrist links |
| Stainless | 303, 304, 316L, 17-4PH | Pin seats and inserts |
| Max part size | 4,000 mm | Across the long axis |
| Anodizing | Clear, color, hardcoat | Hardcoat adds 20–30 μm |
| Laser marking | 1.5 mm min height | Part numbers and traceability |
Why GreatLight
Fifteen years of hard-metal production
Founded in 2011, three wholly-owned plants, 150 technicians.
15Y
Machining since 2011
Fifteen years of production work in Dongguan, next to Shenzhen, plus a factory in Singapore.
127
CNC machines on the floor
16 five-axis, 12 four-axis, 27 three-axis, 16 mill-turn centers and the support equipment around them.
±0.005
Tolerance held in production
Not a lab number. It is what the process repeats on joint bores and flange faces.
99.99%
Qualification rate
Raw material check, in-process monitoring, final inspection before anything ships.
12H
Quote and DFM analysis
We return a quotation with a free DFM review within 12 hours. Production can start in 24 hours.
4
Quality certifications
ISO 9001:2015, IATF 16949:2016, ISO 13485:2016 and ISO 27001:2022.
7,600 m²Manufacturing space
3Wholly-owned plants
150Technicians
<2%Historical late-delivery rate
Applications
What robot builders ask us to hold
Actuator joint housings
Bore and bolt circle cut in the same operation so the motor flange seats without shimming.
- ±0.005 mm
- One setup
- Ra 0.8–1.6 μm
Wrist links and brackets
Thin-wall sections held stable through roughing, finishing and anodizing.
- 6061-T6
- 7075
- 1.5 mm walls
Prototype joints
One-off and small-batch joints for kinematic testing before tooling is cut.
- No MOQ
- 3–5 days
- 100% inspection
Fixture and datum design
We plan the fixture from your GD&T before the first tool touches the stock.
- Datum planning
- Trunnion work
- In-process checks
FAQs
Questions engineers ask before sending a joint drawing
What makes a robot joint part a good fit for 5 axis cnc machined work?
If the part has features that reference each other on three or more faces, five axes pay for themselves. A joint housing with a motor mount, a bearing bore and cable exits is the classic case.
If your part is a flat cover with holes on one face, a three-axis machine does it cheaper and just as accurately. We will tell you which one your drawing needs.
How do you hold ±0.005 mm on a thin-wall joint housing?
Rough machining leaves stock, the part cools, then finishing takes light radial passes with low clamp force. Bores are measured for roundness and taper, not only diameter.
When hardcoat or anodizing follows, critical fits are masked and re-checked, because coating thickness can eat a tight tolerance.
Which aluminum grade should I choose for a robot arm joint?
6061-T6 covers most housings and brackets. It machines cleanly, anodizes well and keeps cost down.
7075 gives higher strength for wrist links that carry bending load, but it costs more and is harder to weld. 2024 sits between the two and is common in aerospace-style joints.
Can you machine titanium or stainless joint components?
Yes. TC4 (Ti-6Al-4V) and TA2 are used for high-load links, and 17-4PH, 316L and 303 for pin seats, inserts and bushings.
Titanium needs slower cutting speeds and more tool changes. Expect a longer cycle than the same part in aluminum, and plan for it in the schedule.
Do you have a minimum order quantity?
No. We run from a single prototype to 10,000+ part runs. Prototype joints are common before the kinematic design is frozen.
The first article and the production run use the same CAM and fixtures where possible, so what you test is what you get in volume.
How fast can I get a quote and parts?
Quotation and a free DFM analysis come back within 12 hours of a complete drawing and model. Production can start within 24 hours after approval.
Parts normally ship in 3–5 days depending on quantity, finishing and material availability.
What inspection data comes with the parts?
Every part is inspected before shipment: raw material check, in-process monitoring and final inspection. Dimensional reports are available on request.
We work to ISO 9001:2015, with IATF 16949:2016, ISO 13485:2016 and ISO 27001:2022 also held.
Is my design kept confidential?
Uploads are secure and confidential. We can sign an NDA before you send drawings, and the NDA page is on the site.
Files are not shared outside the project team, and customer models are not used as samples or marketing material.
Send your joint drawing, get a real number
Upload the STEP file and drawing. An engineer reviews the datums, the wall sections and the finishing before we quote.
12-hour quote100% inspectionNo minimum orderNDA on request
