Five-Axis CNC Machined Aluminum Rotary Actuator Body
Rotary actuator bodies five-axis machined from 6061-T6 billet, with a through bore held to H7 and 0.008 mm roundness, end flanges square to the bore within 0.015 mm and ports placed on faces that sit at compound angles to the axis. Each body is leak tested at 1.5 times working pressure before the ports are plugged.
- Through Bore to H7
- Ports on Compound Faces
- Flange Faces Square 0.015 mm
- Leak Tested Before Shipment
*The two numbers that decide whether this part works are bore roundness and port angle. Send both, plus the seal drawing, because a lip seal tolerates less ovality than an O-ring.
Rotary Actuator Body Overview
A rotary actuator body is a cylinder with a bore that has to stay round, two end faces that have to stay square to that bore, and ports that have to arrive at the bore at the right angle. On a three-axis machine those features are cut in three set-ups and the errors add up.
Cutting the part on a five-axis machine with a trunnion lets the bore, both flanges and the angled ports be machined from one datum. The bore is then honed to size rather than bored, which removes the tool mark that a seal would otherwise ride over.
6061-T6 Aluminium Billet
Billet is used rather than plate because the bore runs through the short grain direction, which keeps the wall from moving after honing. 6061 also hard anodizes predictably, which matters on a bore that sees a sliding seal.
7075-T6 or 6082-T6
7075-T6 is chosen when the body is also a structural pivot and the flange carries a bending moment. 6082-T6 is used in Europe where the material certificate has to match a specific standard, and it machines nearly as well.
For an air actuator running dry, the bore finish and the anodizing matter more than the alloy; for a hydraulic body at 200 bar, alloy and wall thickness decide.
Rotary Actuator Body Specifications
Five-axis data for actuator bodies, with bore, squareness and port values that determine whether the seal tracks and the circuit seals.
| Specification | Machining Data | Specification | Machining Data |
|---|---|---|---|
| Product | Rotary Actuator Body / Cylinder Barrel | Machining Process | 5-Axis CNC Milling, Boring, Honing |
| Material | 6061-T6 Aluminium Billet | Bore Diameter | Ø 25 – 120 mm, H7 Through |
| Bore Roundness | 0.008 mm | Bore Straightness | 0.01 mm over 200 mm |
| Flange Squareness | 0.015 mm to the Bore Axis | Port Position | ±0.03 mm on Compound Faces |
| Wall Thickness | 5 – 10 mm | Surface Finish | Ra 0.8 µm Bore, Ra 1.6 µm Flanges |
| Port Threads | G1/8 – G1/2 or NPT, Sealed Face Spotfaced | Pressure Test | 1.5 × Working Pressure, 10 min Hold |
| Customization | Trunnion Bosses, Sensor Slots, Mounting Feet | Lead Time | 7 – 9 Days Sample, 14 – 18 Days Batch |
| Inspection | CMM Bore Axis and Port Angles, Air Gauge Bore, Leak Test Record | Packing | Plugged Ports, VCI Wrap, Foam Crate |
Key Features of Our Actuator Bodies
One set-up for bore, flanges and ports.
Bore Honed, Not Just Bored
Honing after boring removes the helical tool mark and holds roundness to 0.008 mm, so the seal wears evenly instead of tracking a single high spot.
Ports Cut at the True Angle
Angled ports are milled with the part rotated on a trunnion, so the port axis meets the bore at the drawing angle rather than at the nearest 90°.
Flanges Square to the Bore
Both end faces are faced with the bore as the reference, holding squareness to 0.015 mm, which stops the end cap from cocking and pinching the seal.
Every Body Leak Tested
Each body is plugged and held at 1.5 times working pressure for ten minutes, and the gauge reading is recorded against the serial number.
Body whose ports have to meet the bore at an angle?
Surface Finishes for Actuator Bodies
A coated bore changes the seal fit, so the finish is agreed before the bore size is fixed.
| Finish | Main Purpose | Finish | Main Purpose |
|---|---|---|---|
| Hard Anodizing | Wear resistance in the bore of a dry-running actuator | Type II Anodizing | Corrosion protection on the external faces |
| Masked Bore | Keeps the bore at H7 after coating | PTFE Impregnation | Low friction on unlubricated air cylinders |
| Chromate Conversion | Conductive body where a ground strap lands | Laser Marking | Port lettering and stroke direction |
*Hard anodizing adds 25 to 50 µm per surface. Bores that are hard anodized are machined 40 µm under size and honed after coating, never before.
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Five-Axis Machining Process
The bore and the port faces are machined in the same five-axis set-up, so a port cannot end up half a degree off the axis it feeds.
01. Seal and Port Review
Check the seal cross-section against the bore tolerance, confirm the port threads and the angle of every port on the model before the first cut.
02. Machine the Datum End
Face the datum end and bore the pilot in one set-up, then use that bore as the reference for every later operation rather than the outside of the billet.
03. Five-Axis Bore and Ports
Rotate the part on the trunnion to bore through, then to mill each angled port face and drill the port, keeping the part clamped throughout.
04. Hone the Bore
Hone to final size with a cross-hatch pattern, air gauge the diameter at three depths and record roundness before the body goes to test.
05. Plug, Test and Pack
Deburr the ports, plug them, pressure test at 1.5 times working pressure, then wrap in VCI and crate with the test record inside.
Send the actuator section and the port schedule, and we will quote the body with the bore honed and the ports on their true angles.
Rotary Actuator Body FAQs
Because the ports sit on faces that are not perpendicular to the bore. On a three-axis machine each port needs its own fixture and the angular error accumulates; on a trunnion all of them come from one datum.
0.008 mm after honing on a body up to 200 mm long. Bored only, the same body holds about 0.02 mm, which is enough for an O-ring but marginal for a lip seal.
By 25 to 50 µm per surface. The bore is machined undersize and honed after coating, so the finished diameter is the one on the drawing.
1.5 times working pressure for ten minutes as standard; higher on request with a thicker wall. Test pressure and hold time are recorded for each serial number.
Yes, up to 40 mm long and Ø 30 mm. Longer bosses are better as separate pins pressed in, because a long boss on a thin wall distorts the bore when it is machined.
The port face is spotfaced square to the thread and the thread is cut to a pre-plate size, so a bonded washer or an O-ring port seal sits flat without a sealant buildup.
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