In Situ Precision Alignment


Misalignment is major causes of vibration in rotating equipment, vibration that means increased maintenance and reduced machine life. With proper alignment, reductions in maintenance and operating costs can easily reach into six figures per year.

When shafts are misaligned, forces are generated that can produce stresses on the rotating and stationary components. Even when couplings do not fail from the stresses produced by gross misalignment, bearings and seals will most certainly fail under these conditions. In extreme cases of misalignment, even the shafts may fracture and break. Maintenance personnel too often rely on manufacturer’s claims that their “self-aligning” bearings and “flexible couplings” compensate for shaft misalignment.

There are two components of alignment: offset and angular (see Fig. 1 and Fig. 2).

Offset alignment, or parallel alignment is the distance between the shaft centers of rotation measured at the plane of power transmission. It is typically measured at the coupling center.

Angular alignment is the difference in the slope of one shaft compared to the slope of the mating shaft.

There are also two planes of potential misalignment: horizontal and vertical. Each plane has both offset and angular components. Thus, there are four alignment parameters: horizontal angularity (HA), horizontal offset (HO), vertical angularity (VA), and vertical offset (VO).

Alignment methods

Of the many methods available to measure shaft alignment, the two most popular are dial indicator alignment and laser alignment.

Laser alignment offers the potential for much greater accuracy than dial indicators, as well as considerable time savings.

Condition Monitoring Ltd. uses the CSI ULTRASPEC 8117 dual laser alignment.

Why Align Machinery to Tight Tolerances?

Aligning machinery to acceptable tolerances:

  • Reduces energy costs
  • Increases bearing life
  • Increases seal life
  • Increases coupling life

How does Alignment to Specific Tolerances Save Energy?

  • An aligned machine needs less power to perform its work.
  • A plants that moves from hit-or-miss alignment to precision alignment can typically reduce their energy cost from 5% to 12%.

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