Shaft alignment, often called “coupling alignment”, is a process to make two or more rotating shafts co-linear, or in the same straight line, both vertically and horizontally. Shaft alignment can be done utilizing several methods and tools, such as straightedges, calipers, dial indicators, optics, or laser systems. Of these, laser shaft alignment is the fastest and most accurate.
Laser shaft alignment systems offer numerous advantages:
- Laser beams are not affected by gravity or bracket sag.
- Laser tools are rotated to various positions around the rotational centers of shafts. This process allows the laser to measure just the rotational centers, and is not affected by shaft or coupling eccentricity, or runout.
- Most laser shaft alignment systems have on board software to calculate extremely accurate values for shimming and horizontal corrections.
- Some laser shaft alignment systems use “live” measuring modes to monitor the actual shaft rotational centers during the movement process taking into account both intended and unintended movements, allowing the aligner to monitor total movement, and know when to stop. Some of the systems that are unable to monitor the actual “live” position of the shafts relative to one another will at least provide approximate positional estimates based on the static measurement outcome plus any aligner made adjustments, not taking into account unintended movements.
- Many also allow storing the corrected alignment values digitally, for later integration into maintenance record keeping.
- Some laser shaft alignment systems also have programs to measure and correct soft foot, bolt bound or base bound conditions, and other shaft alignment problems.
- A few systems also have capabilities to:
- Measure more than two coupled machines during the same measurement process, allowing the aligner to align machine trains.
- Measure vertically as well as horizontally oriented machines.
- Utilize the laser technology to achieve basic geometry measurements, such as flatness, straightness, and parallelism.
- Measure and compensate for dynamic changes in machinery position, such as those caused by thermal growth of machines.
- Accurately measure more complex alignment functions such as cardan shaft, or universal joint parallel alignment.
Laser shaft alignment systems can also measure long-span alignments in situations where spacer shafts are used, such as in cooling towers and paper machine applications.
These laser shaft alignment tools are considered “state of the art” in most industrial and maintenance applications.