When a motor and the machine it drives are not properly aligned, the coupling, bearings, and seals absorb extra stress. Misalignment is a leading source of vibration and early failure in rotating equipment.
Types of Misalignment
- Angular misalignment: the shaft centerlines meet at an angle.
- Parallel (offset) misalignment: the centerlines are parallel but displaced.
- Combined misalignment: a mix of both, the most common real-world condition.
Alignment Methods
Straightedge and feeler gauges are only suitable for rough checks. Dial indicators improve accuracy, and laser alignment systems are now the standard for precision work, giving fast measurements and live corrections for vertical and horizontal moves. Always check for soft foot and pipe strain first, because these can ruin an otherwise good alignment.
Account for Thermal Growth
Machines change dimensions as they heat up. For equipment with significant temperature change, the manufacturer may specify offset targets so that the shafts align at operating temperature rather than when cold.
Balancing and Vibration
Imbalance is another frequent cause of vibration. Rotors such as fans, impellers, and couplings can be balanced in place with portable instruments. After alignment and balancing, record baseline vibration readings so that future changes are easy to spot.
Precision alignment reduces bearing and seal wear, lowers energy consumption, and extends equipment life. It is one of the highest-return, lowest-cost reliability practices available to maintenance teams.