KEVOS® MAKEOS · Maintenance
Shaft Alignment Plan (Rim and Face Corrections with Thermal Growth)
From my rim and face readings, how many shims do I add or remove at each foot so the shafts line up when the machines are hot, and is the running alignment within tolerance as it stands?
Alignment plan for a movable machine coupled to a stationary one: offset and slope at the coupling and the corrections at the front and back feet from rim and face dial readings (as the rim and face alignment tool), the vertical thermal growth of each machine from its foot-to-centreline height and support temperature rise and the cold offset to allow (as the thermal growth for hot alignment tool), the cold shim corrections that give true alignment when hot, and the running offset and angularity if nothing is changed, against your tolerances.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Dial readings (movable machine) | ||
| Rim reading at 6 o’clock (zeroed at 12) | mm | Rim dial reading at the bottom, with the dial zeroed at the top (as the rim and face tool). |
| Face reading at 6 o’clock (zeroed at 12) | mm | Face dial reading at the bottom, zeroed at the top. |
| Diameter of the face reading circle | mm | Diameter of the circle the face indicator travels on. |
| Coupling to front foot of movable machine | mm | Distance from the coupling to the front feet of the movable machine. |
| Coupling to back foot of movable machine | mm | Distance from the coupling to the back feet. |
| Thermal growth | ||
| Stationary machine: foot to shaft centreline | mm | Height from the stationary machine’s feet to its shaft centreline. |
| Stationary machine: expansion coefficient | µm/(m·K) | Expansion coefficient of the stationary machine’s supports. |
| Stationary machine: support temperature rise | K | Rise in temperature of the stationary machine’s supports from cold to running. |
| Movable machine: foot to shaft centreline | mm | Height from the movable machine’s feet to its shaft centreline. |
| Movable machine: expansion coefficient | µm/(m·K) | Expansion coefficient of the movable machine’s supports. |
| Movable machine: support temperature rise | K | Rise in temperature of the movable machine’s supports. |
| Tolerances | ||
| Offset tolerance at the coupling | mm | Largest running offset you accept at the coupling. |
| Angularity tolerance | mm/100 mm | Largest running angularity you accept. |
Method and formulas
- Offset = rim ÷ 2; slope = face ÷ face diameter; correction at a foot = offset + slope × distance, positive meaning add shims (as the rim and face alignment tool).
- Growth = α H ΔT for each machine; the movable machine rises by g₂ − g₁ more than the stationary one when hot (as the thermal growth tool).
- Cold correction = correction − (g₂ − g₁) at both feet; running offset if unchanged = offset − (g₂ − g₁); angularity = slope × 100.
- Example: add 0.12517 mm at the front feet and add 0.29183 mm at the back; the movable machine grows 0.099 mm more than the stationary one.
Limitations
- Vertical plane only; repeat for the horizontal plane with side readings (no thermal term unless the supports grow sideways).
- Rigid feet with no soft foot; check soft foot before shimming.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Plan shims for a pump or fan alignment
- Allow for thermal growth when aligning cold
- Decide whether a machine needs realigning
Who it is for
- Millwrights
- Maintenance fitters
- Reliability engineers
What you get
- Offset, slope and foot corrections from the readings
- Thermal growth and cold offset
- Cold shim corrections and running misalignment
Interpreting the result
- A machine that runs hotter must be set low when cold so it grows into line.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 2645–2650, 375–376. Topic reference; no source tables or recommended settings are reproduced.
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Open the Shaft Alignment Plan (Rim and Face Corrections with Thermal Growth) calculator
