A continuously rotating end-of-arm tool needs a rotary path for every utility that crosses the rotating boundary. A fluid rotary union can carry suitable air or vacuum passages, while a compatible electrical slip ring carries power and signals. Choose the combined interface from the tool’s utility list rather than assuming that one rotary connector covers everything.
End-of-arm tooling, or EOAT, includes the gripper and its attached equipment. A wrist that turns repeatedly in one direction makes an ordinary hose-and-cable loop a different design problem from a wrist with bounded rotation.
Count independent passages before counting ports
DSTI’s robotics application page describes multi-passage vacuum/pneumatic interfaces and integrated electrical transfer. That establishes an available architecture, not the suitability of a particular assembly for your robot.
Prepare a routing schedule with a row for each independent pressure or vacuum function. Two fittings on a tool do not necessarily require two passages if they share a circuit, while two functions that must remain isolated cannot be combined merely to save space. Put the intended isolation requirement in the drawing.
| Utility crossing the wrist | Selection information |
|---|---|
| Compressed-air feed | Media, working conditions, required flow and passage connections |
| Vacuum feed | Vacuum conditions, evacuation requirement and permitted leakage |
| Separate release/blow-off feed | Whether it must be independent of the vacuum route |
| Tool electrical power | Voltage, current per circuit and startup load |
| Data or sensor signals | Actual protocol, circuit arrangement and connection details |
If vacuum is generated on the moving tool, the rotating interface may carry compressed air instead of a dedicated vacuum line. If the generator stays stationary, the vacuum path itself crosses the wrist. This is an architectural distinction to resolve before passage selection, not a claim that either arrangement is universally better.
A single air passage is not a complete multi-utility wrist
The DSTI SPS series page describes a single-passage air/gas unit for pressure or vacuum that can integrate with through-bore electrical slip rings. It is a useful counterexample: integration with an electrical device does not create additional independent fluid passages.
Do not select from a headline maximum pressure and maximum speed alone. Confirm the exact model, medium, pressure/vacuum conditions and duty together. Treat flow performance and leakage requirements as separate questions; a connection that fits mechanically may still fail to meet the tool’s evacuation needs.
The same series page identifies air/gas as its medium. It does not qualify that product for hydraulic oil, chemicals or food contact. DSTI’s media-compatibility FAQ limits recommendations to listed media and advises discussing separation when combining air/gas with another fluid. Retain that model boundary even if another product from the supplier supports the additional medium.
Specify data by protocol, not by a wire count
A continuity path for a digital input is a different requirement from a network connection. Give the electrical-interface supplier the protocol, connector arrangement, circuit current and rotational duty. “Has a slip ring” is insufficient evidence that a particular Ethernet or fieldbus path is supported.
On a hypothetical rotating vacuum tool, separately label the pressure supply, vacuum measurement, release command and tool power. Then draw the fixed side and rotating side of each. The drawing makes omissions visible without claiming any measured cycle time, gripping force or service life.
Send one combined interface schedule to the suppliers
Before ordering, reconcile the fluid and electrical selections against the same envelope and mounting drawing. Include the tool’s mass and loads, restraint approach, utility conditions, connector access and maintenance needs. Ask which conditions are model limits and which require custom engineering.
The practical outcome is a complete route across the wrist, with no utility left to an unspecified cable or hose. For choosing the gripping principle, see the parallel-jaw, vacuum, soft and dexterous gripper comparison. That choice sets the utilities the rotating interface must carry.
DSTI living pages checked October 14, 2026; first publication dates are not stated. The architecture example was not built or tested, and no whole-cell reliability claim is made.