Picture a fan or pump that has been getting louder for months. Bearings keep being replaced, a coupling has been changed twice and a seal never seems to last. Each repair clears the symptom for a while, then the same failure returns. When that pattern repeats, the repair is often not the problem. The cause can be how the machine turns or how it is lined up.
Why repeat failures often point to imbalance or misalignment
Two common causes of vibration in rotating machinery are imbalance and misalignment. Imbalance means mass is unevenly distributed around a rotating part, so it pulls on its bearings with every turn. Misalignment means the driving and driven shafts do not sit on the same centreline, which loads bearings, seals and couplings. From the outside both can look alike: heat, noise, loosening fixings and short bearing life.
This is why replacing parts without finding the cause can leave a site repeating the same job.
How to tell which one you are dealing with
Vibration analysis is the usual starting point. Measuring vibration at several points on the machine and at different frequencies helps separate imbalance from misalignment, and from other causes such as looseness or worn bearings. Imbalance tends to show at the machine’s running speed, while misalignment often shows at multiples of it and along the shaft. Readings taken before and after any correction also show whether the work made a difference.
What dynamic balancing involves
Dynamic balancing measures how a rotor behaves while it is turning, then corrects the uneven mass by adding or removing weight at set positions. It is commonly applied to fans, impellers, rotors and similar parts. A component that has been repaired, refurbished, worn or fouled with build-up may no longer turn true, so balance is worth checking after major work as well as when vibration appears.
What laser alignment involves
Laser shaft alignment uses laser measurement to show how far two shafts are offset or angled relative to each other, then guides adjustment until they sit within tolerance. It replaces judging alignment by eye or with a straight edge. Good alignment also depends on the basics: a stable base, no soft foot (a machine foot that does not sit flat) and an allowance for how pipework and temperature change position once the machine is running.
A sensible order of work
- Measure first, so you know what you are correcting.
- Check the basics: base condition, coupling, fixings and soft foot.
- Balance any rotating parts that show imbalance.
- Align the shafts and recheck.
- Measure again and keep the readings for comparison.
Talk to EES Electro-Mechanical
Greater Manchester and the North West
EES Electro-Mechanical provides vibration analysis, dynamic balancing and laser alignment for motors, pumps, fans and gearboxes, alongside motor rewinds, pump repair and gearbox refurbishment, for sites across Greater Manchester and the North West. If you are seeing repeat failures, talk to the team about where to start, whether that is a vibration survey, a balance check or an alignment. You can see the full range of EES Electro-Mechanical services, call 0161 655 4421 or contact the team.
EES Electro-Mechanical is part of EES Group Holdings.