Foil air bearing design and installation guide
Foil Thrust Air Bearing
Mounting and Prep
​Clean base plate, housing, bearing, runner (thrust disc), and fasteners with isopropyl alcohol only. Do not lubricate. Align the four pin-slots on the bearing with precision dowel pins in the base plate; apply a light press-fit to seat the bearing.
Axial Clearance
The shaft must pass freely through the bearing’s inner diameter (ID) without friction or binding. Set the axial clearance — the gap between the top foil and the runner surface — to 7.5 – 12.5 µm (0.00030 – 0.00050 in). Use calibrated shims or feeler gauges at several positions (e.g., 0°, 90°, 180°, 270°) to ensure uniform clearance around the runner. After shimming, verify free rotation by hand before performing break-in at low speed.
Design & Installation Guides
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-Foil AIR BEARINGS
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Orientation & Thrust Reversal
To avoid thrust reversal, use two thrust bearings—one CW + one CCW— on opposite sides of the runner when possible. Label and verify arrow direction (CW/CCW).
Base Plate
​The base plate is a mounting fixture provided by the customer. Its function is to fix/locate the bearing within the bearing housing (alignment and retention). It does not belong to the shaft/rotor design and carries no rotational features. Dimensions, hole patterns, and dowel locations are application-specific and should match your housing and datum scheme.
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Notes on Operation
​Foil bearings are self-acting; under rotation they generate their own gas film and typically do not require external pressurization. (Retain optional purge air only if your design needs debris control or cooling.)
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Axial Clearance Check
Place calibrated shims between runner and top foil; adjust hub/runner position to 7.5–12.5 µm, verifying at 0°, 90°, 180°, 270°. Tighten hub screws in a star pattern.
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Orientation Check
If using dual bearings, install CW on one side and CCW on the other side of the runner; confirm arrows before closing.
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Break-in Procedure Check
Rotate by hand to confirm no rub. Power up and ramp: 10% → 30% → 60% → 100% speed, holding 1–2 minutes at each step to establish the film. Listen for contact; if detected, stop and re-verify clearance/alignment.
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Final QA Check
Recheck axial float at operating temp if applicable; document measured clearances.
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CW and CCW directions shown below.
Foil Thrust Air Bearing Flow Dynamics
Figure 1: Foil bearings are self-acting; the hydrodynamic gas film forms with speed—no external pressurization is required for operation.
Foil Journal Air Bearing
Mounting & Prep
​Use lint-free wipes + isopropyl alcohol (no oil). Seat the bearing in the housing using dowel pins/screws with a light press, or an ISO H7/g6transition fit. Slide the shaft/rotor through carefully to avoid touching the foil edges.​
Radial Clearance
​​Target 7.5–12.5 µm radial clearance between the top foil and rotor. Verify with calibrated feeler gauges at 0°, 90°, 180°, 270°; adjust concentricity as needed.​
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Base Plate
​The base plate is a mounting fixture provided by the customer. Its function is to fix/locate the bearing within the bearing housing (alignment and retention). It does not belong to the shaft/rotor design and carries no rotational features. Dimensions, hole patterns, and dowel locations are application-specific and should match your housing and datum scheme.
Fasten
Tighten housing screws in a cross pattern; confirm free rotation by hand.
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Orientation
​Match the bearing’s CW/CCW marking to your rotation direction.​
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​Break-in Procedure Check
​​Ramp speeds in stages (10% → 30% → 60% → 100%), holding ~1–2 minutes at each step. Stop if any rub is detected, re-verify clearance and alignment.
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Final QA Check
Measure current draw or temperature rise at rated speed to baseline performance.
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CW and CCW orientation shown below.
Foil Journal Air Bearing Flow Dynamics
