Cobot Elbow Linkage 5-Axis Single-Setup Machined 0.01mm Coaxial Bores Set
Cobot Elbow Linkage
,5-Axis Machined Arc Linkage
,0.01mm Coaxial Bore Linkage
The swept-arc elbow linkage is the load-transfer member between the shoulder housing and the wrist of a collaborative robot. It is produced as one continuous curved body with a mounting flange at each end, so the arc profile, the twin coaxial bores and the flange bolt circles all have to be generated in a single five-axis clamping on 6061-T6 aluminium plate. Roughing removes the bulk of the blank, finishing generates the curved skin, the locating spigots and the tapped holes, and the finished part is verified on a CMM against the drawing before it leaves the shop.
Every batch is traceable: material certificate to heat number, machining program revision, anodizing batch and inspection record are filed against the delivery note so a replacement part can be reproduced years later without a new sample round.
Manufacturing Process
- 1Blank preparation. 6061 or 7075 aluminium plate is sawn to an oversize block with 2-3 mm allowance on every face, stress-relieved where required, and stamped with a heat-number trace code.
- 2Five-axis machining, the core operation. The part is a large-radius curved body with a hollow section and two coaxial bores that must stay concentric in both directions. Because the flange faces at the two ends are not parallel to any single machine axis, the geometry can only be cut reliably with a five-axis machining centre holding the workpiece in one clamping and milling with linked rotary and linear motion. Rough milling peels off the bulk of the allowance with a large-diameter cutter; the semi-finish pass equalises stock on the curved wall; the finish pass generates the arc contour, the mounting register and the bolt holes. Holding the part once removes the re-datum errors that would otherwise come from flipping the workpiece between three-axis operations.
- 3Deburring and cleaning. Sharp edges are broken by hand and with a nylon abrasive brush, bores are cross-brushed, and the part is ultrasonically degreased in a two-stage bath before drying.
- 4Surface treatment (optional). Sandblasting for a uniform matte grain, Type II colour anodizing, or hard Type III anodizing at 25-40 microns for wear resistance on sliding and clamping faces; polishing is available where a decorative finish is required.
- 5Full dimensional inspection. Form and position tolerances, bore concentricity and flange flatness are verified on a coordinate measuring machine; the inspection report, material certificate and finish-thickness readings ship with the parts.
Process Difficulty Control
The hard part of this component is the continuous curved thin wall: material is only 3-5 mm thick along the outside of the arc, so radial cutting force pushes the wall away from the cutter and generates chatter, which shows up later as poor roundness and a noisy surface. We control it with a dedicated support fixture that backs the wall with a contoured nest, a stepped tool path that keeps radial engagement constant, low-radial-engagement trochoidal roughing, and cutting parameters validated on the first article. Spring-back is compensated directly in the CAM model after the first CMM result.
Applications
- Collaborative robots (cobots) - the primary use, as the elbow joint link in 3C assembly, screw fastening and connector insertion cells
- Industrial robot arms - lightweight six-axis manipulators for pick-and-place, sorting and machine tending workstations
- Automated inspection equipment - swing arms that carry a camera module and tilt it to the required viewing angle
- Medical automation - light-load transfer linkages in laboratory and clinical handling equipment
- Intelligent logistics and warehousing robots - light-load picking manipulators and shuttle arms
- Laboratory automation and teaching platforms - research robot arms and educational motion rigs
Key Features
Single-Setup Arc Machining
A 180 degree swept body is finished in one five-axis clamping, so the arc profile and both flange faces share the same datum.
Twin Coaxial Bores
Both bearing bores are bored in the same cycle and held to +/-0.01 mm for straight shaft and bearing alignment.
Thin-Wall Stability
Contoured nest fixture plus trochoidal roughing keeps the 3-5 mm curved wall free of chatter and spring-back.
Wear-Resistant Finish
Type III hard anodizing at 25-40 microns raises surface hardness on clamping and sliding faces.
Specifications
| Material | 6061-T6 aluminium (7075-T6 on request), plate or sawn block |
|---|---|
| Machining | Five-axis CNC milling, single clamping, linked rotary and linear motion |
| Dimensional tolerance | +/-0.01 mm on bores, spigots and flange positions |
| Surface roughness | Ra 1.6 um as machined, Ra 0.8 um on request |
| Finish options | Sandblasting, Type II colour anodizing, Type III hard anodizing, polishing |
| Inspection | CMM report, material certificate, finish thickness record |
| Typical lead time | 5-9 days for samples, 15-25 days for series production |
| Packing | Individual bubble wrap with foam corner protection in export carton |
Customisation Service
Send a STEP, IGES or DWG file with the tolerance callouts, the required finish and the annual quantity. We return a machining feasibility review within two working days, covering datum strategy, thin-wall risk, suggested material grade and an item price for sampling and for series production. Design changes to the arc radius, bore layout, flange pattern and tapped hole positions are all supported; we can also propose a lightening pocket layout to reduce arm inertia without cutting stiffness.
Ready to quote your elbow linkage? Send drawings and quantity - sample parts can be shipped within one week of drawing approval.
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