Adapted from SKF reference material on laser shaft alignment.
Why shaft alignment matters
Misaligned shafts are one of the biggest drivers of rotating-equipment failures – SKF attributes up to half of all costs related to rotating machinery breakdowns to shaft misalignment. Aligning shafts accurately prevents many of these failures and cuts the unplanned downtime and lost production that come with them. With maintenance budgets under constant pressure, precise alignment is one of the most cost-effective reliability improvements a plant can make.
What is shaft misalignment?
Two coupled machines have to be aligned in both the horizontal and the vertical plane. In each plane, misalignment shows up in two forms, and in practice almost every machine has some combination of the two:
- Parallel misalignment (offset): the shaft centerlines are parallel but displaced from each other.
- Angular misalignment: the shaft centerlines meet at an angle.
- Correct alignment: the centerlines of both shafts form one straight line while the machines are running.
What misalignment costs you
- Higher friction, and with it higher energy consumption
- Early bearing and seal failures
- Early shaft and coupling failures
- Excessive seal lubricant leakage
- Broken coupling and foundation bolts
- More vibration and noise
Shaft alignment methods compared
| Method | Accuracy | Speed | Ease of use |
|---|---|---|---|
| Straight edge | Poor | Good | Good |
| Dial indicators | Good | Poor | Poor |
| Laser shaft alignment | Good | Good | Good |
A straight edge is fast but too coarse for anything beyond a rough check. Dial indicators can be accurate, but they are slow and depend heavily on the technician’s skill (see our Reverse Dial Alignment guide). Laser alignment systems are quicker and simpler to use, are at least as accurate, and give repeatable results without specialist training.
Choosing a laser alignment system
Before buying, list the machines you actually need to align and what each job requires. A top-end system that handles every possible application can be an expensive mistake if technicians find it hard to use day to day. Most alignment work is a horizontally mounted electric motor driving a pump or fan through a single coupling – for that, the priority is a system that sets up quickly and is easy to operate.
Compare the SKF range feature by feature in the SKF Shaft Alignment Tool Comparison / Selection Table, or go straight to the models:
- SKF TKSA 11 – entry-level, uses your phone or tablet
- SKF TKSA 31 – touchscreen display unit with machine library
- SKF TKSA 41 – wireless, free measurement positions
- SKF TKSA 51 – app-based, vertical alignment and target values
- SKF TKSA 71 and TKSA 71/PRO – spacer shafts, machine trains and dial gauge mode
Don’t forget the shims
Correcting alignment usually means moving the motor both sideways and up or down, and height corrections are made with shims. Precision machinery shims are available as single packs or in cased kits – see our Shims English/Metric collection.