Laser shaft alignment systems measure the relative position of two coupled shafts using laser beams and precision detectors. Modern systems like the Easy-Laser XT series achieve measurement resolution of 0.001mm, allowing accurate positioning of rotating machinery to within thousandths of a millimetre.
Misalignment causes over 50% of rotating machine failures. Correctly aligned shafts reduce vibration, lower noise levels, decrease energy consumption, and extend bearing and seal life. These improvements typically justify alignment system costs within 3 to 6 months.
Pre-Alignment Preparation
Proper preparation accounts for much of the success of any alignment job. Rushing through preparation often leads to repeated measurements and wasted time.
- Ensure the machine is isolated and locked out according to site safety procedures
- Clean the baseplate and machine feet, removing rust, paint, debris and old shims
- Check that anchor bolt holes allow adequate movement for alignment adjustments
- Verify the coupling is in good condition and that coupling bolts are accessible
- Place fresh shims under each foot to provide adjustment range in both directions
Starting Shims
For new installations or complete realignments, place 2mm or 3mm shims under each machine foot before starting. This provides room to raise or lower the machine as needed. These starting shims are replaced with the correct thickness once alignment measurements are complete.
Soft Foot Check
Most laser alignment systems include a soft foot measurement program. This check should be completed before taking alignment readings, as soft foot affects both the accuracy and repeatability of measurements.
The soft foot check measures vertical movement at each machine foot as anchor bolts are loosened individually. Any foot showing more than 0.05mm of movement requires correction with shims before proceeding.
Important
Skipping the soft foot check is a common cause of alignment problems. Internal stress from soft foot distorts the machine frame, causing alignment readings to change each time bolts are loosened and retightened.
Mounting the Measuring Units
Laser alignment systems use two measuring units mounted on either side of the coupling. Each unit contains a laser emitter and a detector. The units communicate wirelessly with a display device that calculates alignment values.
Stationary Unit
Mount on the fixed machine (typically the driven equipment such as a pump or compressor).
Movable Unit
Mount on the machine that will be adjusted (typically the motor or driver).
- Select brackets suitable for the coupling type (chain brackets, magnetic brackets, or shaft clamps)
- Attach brackets securely to the shafts or coupling hubs at the same rotational position
- Mount the measuring units on the brackets and adjust so the laser beams strike each detector
- Enter the machine dimensions into the display unit (distances between feet and coupling)
Taking Measurements
The measurement process involves rotating the shafts while the laser system records data points. Modern systems can measure continuously during rotation, collecting hundreds of data points for high accuracy.
Measurement Methods
Easy-Laser systems offer up to five different measurement methods to suit various conditions:
Continuous Sweep
Rotate the shafts while the system continuously records hundreds of data points. The quickest and most accurate method for coupled machines where both shafts rotate together.
EasyTurn (Manual Rotation)
Record points manually during shaft rotation with a minimum of 20 degrees between points. Useful when continuous rotation is difficult or when more control is needed.
9-12-3 Clock Method
Take readings at fixed clock positions (9 o’clock, 12 o’clock, and 3 o’clock). A traditional approach useful when shaft rotation is limited.
Uncoupled Sweep
For machines where shafts cannot be rotated together. Each shaft is rotated independently while the laser passes over the stationary detector on the other unit.
Measurement Quality
Most laser systems display a quality indicator for each measurement. Poor quality readings may indicate loose brackets, shaft axial movement, or coupling backlash. Address the underlying cause before accepting results.
Making Corrections
Once measurement is complete, the display unit shows the correction values needed at each machine foot. Vertical corrections are made by adding or removing shims. Horizontal corrections are made by moving the machine sideways using adjustment bolts or pry bars.
- Correct vertical offset first — Add or remove shims at each foot according to the displayed values. Positive values indicate shims needed; negative values indicate shims to remove.
- Tighten anchor bolts and remeasure — Tighten all bolts to their specified torque before taking verification measurements.
- Correct horizontal offset — Loosen anchor bolts slightly and move the machine sideways as indicated. Easy-Laser systems provide 360° live adjustment mode, showing machine movement in real time as you make corrections.
- Final verification — Take a final set of readings with all bolts tightened. Confirm values are within tolerance before completing the job.
Do Not Force
Never force shims under machine feet. If a shim will not slide in, the gap is smaller than expected. Remeasure if necessary.
Limit Shim Count
Keep shim stacks to 3 or 4 pieces where possible. Excessive shims compress under load and may create soft foot.
Alignment Tolerances
Acceptable alignment tolerances depend on the operating speed of the machinery. Higher speeds require tighter tolerances. Most laser alignment systems include built-in tolerance tables based on shaft RPM.
| Shaft Speed | Offset (mm) | Angularity (mm/100mm) |
|---|---|---|
| Up to 1000 RPM | 0.10 | 0.10 |
| 1000 to 2000 RPM | 0.08 | 0.08 |
| 2000 to 3000 RPM | 0.06 | 0.06 |
| 3000 to 4000 RPM | 0.05 | 0.05 |
| Above 4000 RPM | 0.03 | 0.03 |
Values shown are typical industry guidelines. Always refer to equipment manufacturer specifications where available.
Documentation
Easy-Laser systems save measurement data automatically and can generate reports in PDF and Excel formats. Keeping records of both the initial condition (as found) and the final alignment (as left) provides valuable reference for future maintenance and troubleshooting.
As Found
Record the initial alignment condition before making any corrections. This documents the starting point and helps identify recurring issues.
As Left
Record the final alignment values after all corrections are complete. This becomes the baseline for future checks and demonstrates the work completed.
Machine Templates
Easy-Laser systems allow you to save machine templates with all distance values and settings. This speeds up repeat work on the same equipment and ensures consistent measurement setup across different operators.