Robot Arm Linkage Set 6061-T6 Aluminum Mirrored Pair Weight Matched 0.005mm Bore Coaxial
Mirrored Arm Pair Machining
,Weight Matched Linkage Set
,Assembled Bore Coaxial 0.005mm
Why a Pair, Not Two Arms
A two-arm robot built from two separately ordered links behaves like two different machines. Mass differs, the bores sit at slightly different heights, and the controller has to correct for asymmetry on every cycle. This linkage set is therefore machined as one project: left and right arms are cut from the same plate, finished in the same programme, boring both ends in one setup, then weighed and paired before shipment. The pair arrives matched, serialised and ready to bolt on.
Each arm carries a bearing boss at both ends with a bolt hole circle, an arched web between them, machined lightening pockets inside the arch and internal ribs where the bending moment peaks. Because both bores are cut without releasing the part, coaxiality is a machined result rather than an assembly tolerance.
How the Pair Is Produced
The route treats the set as a single deliverable. Individual steps are skipped for prototypes, but the pairing and weighing steps never are.
Precision Capability
| Characteristic | Held To | Verification |
|---|---|---|
| Bore-to-bore coaxiality | 0.005 mm | CMM, both ends one setup |
| Centre distance, arm to arm | 0.01 mm | CMM, pair comparison |
| Pair weight difference | ±1 g | Calibrated scale, both arms |
| Boss face flatness | 0.01 mm | Granite plate and indicator |
| Bore perpendicularity to boss face | 0.01 mm | CMM, datum face |
| Bolt hole position | 0.02 mm | CMM, best-fit circle |
| Bore tolerances | H7 / G7 per drawing | Bore gauge, every bore |
| Bore surface finish | Ra 0.8 µm | Roughness tester, per pair |
If the drawing requires tighter than the route can repeat, we raise it during quotation and propose a change in design or process instead of accepting a tolerance the arch cannot support.
Custom Linkages
Links are cut to your assembly. Nothing here is limited to a catalogue length or a fixed end pattern.
- Arm length 80-700 mm, boss diameter 30-200 mm, bore 8-120 mm
- Material options: 6061-T6, 7075-T6, 6082-T6, 2024-T351, 304/316L stainless, titanium on request
- End configurations: single boss, double boss, clevis, yoke fork, flange, threaded collar, or mixed ends
- Features: lightening pockets, internal ribs, cable channels, encoder brackets, sensor pockets, hard stops
- Matched handed pairs, three-arm sets and assembly-level stack-up checks
- Optional balancing, stiffness spot checks or fatigue sample runs quoted per project
- Input formats: STEP, IGES, X_T, STL, DXF, 2D drawing with GD&T, or a sample for scanning and rebuild
Confidentiality
- Mutual NDA signed before drawings, models, scans or samples are exchanged
- Files held on a restricted local server, access limited to the assigned engineer and programmer
- Quotations, CMM sheets and shipping labels carry an internal project code, not your product name
- No photograph, sample or reference of your link is released without written approval
- Fixtures, programs and pairing records built for your job remain your property
- Files and backups deleted at project close on request
The Plant
Dongguan Changxinda Precision Technology Co., Ltd has machined custom metal parts since 2008. The floor runs 4-axis and 5-axis machining centres, turn-mill combination lathes, CNC lathes and milling machines, with an ISO 9001:2015 quality system and an in-house CMM room. More than 200 customers in medical equipment, robotics, automotive, aerospace, automation, laser, LED, lithium battery and precision instruments are served from this plant, and 50-60% of output is exported. Handed pairs, weight matching and serialised sets are ordinary work here, not a special request.
Delivery on Paired Sets
| Stage | Lead Time | Included |
|---|---|---|
| Quote and DFM | Within 24 hours | Tolerance chain, pairing plan, cycle estimate |
| First pair, 1-5 sets | 5-10 days | Weight record, CMM report, trial assembly |
| Repeat sets, 5-20 | 10-18 days | Serialised pairs, progress report |
| Programme supply, 20+ | Scheduled | Staged shipments against your build plan |
- Capacity around 10,000 pieces per month for this linkage family
- Repeat sets reuse the same programme and pairing records, so a spare arm still matches the pair it belongs to
- Each set allocated across two machining centres to protect your date
- Express, air and sea freight; EXW, FOB or CIF; arms packed as a labelled pair to prevent mixed shipments
- Rush capacity for line-down situations, quoted with a date we can hold
Key Features
- Left and right arms cut from one plate for identical material condition
- Mirrored tool paths from a single programme
- 0.005 mm bore-to-bore coaxiality from one-setup boring
- Pair weight matched within 1 g and recorded in the inspection sheet
- Arched web with internal ribs for stiffness at minimum mass
- Laser serials linking each arm to its pair and revision
- Trial assembly against your joint centres before dispatch
- NDA-protected handling with project-code documentation
Typical Applications
- Industrial robot upper arm to forearm links
- Collaborative robot joint-to-joint connecting arms
- Humanoid robot limb segments
- Gantry and pick-and-place arm extensions
- Semiconductor handling robot arm links
- Medical and laboratory robot linkage arms
- Exoskeleton and rehabilitation structure links
- Automation articulated arm assemblies
FAQ
Q: Do the two arms have to be ordered together?
A: For a matched pair, yes — that is the point of the set. If you need a single replacement later, we cut it from the stored programme and pair it against the recorded weight and serial of the original set.
Q: How is the 1 g weight match achieved?
A: Both arms come from the same plate and the same programme, so the starting difference is small. Final matching is done by trimming pocket allowances or adding balance holes, then verified on a calibrated scale.
Q: Will you sign an NDA before we share the arm assembly?
A: A mutual NDA is signed first, covering drawings, models, scans and samples. Pairing records are covered by the same terms.
Q: Can both bearing bores really be cut in one setup?
A: Yes. The link is held once and both ends are bored in the same cycle, so coaxiality is set by the machine axis. Re-clamping is what normally destroys this on a long link.
Q: What is the minimum order?
A: One pair. There is no tooling charge and no programming fee, so a single matched set for a prototype build is a normal order.
Q: Can you match an existing arm we already have in production?
A: Send the drawing or the part. We rebuild the model if needed, confirm material and treatment, and quote against the measured geometry rather than an assumption.
Q: What do you need to quote?
A: 2D drawing with tolerances, 3D model, quantity of pairs, material, treatment and target date. Quote and DFM comments return within 24 hours.
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