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Shaft Alignment - Fundamentals
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Shaft alignment is process of positioning (or) aligning of shaft center lines of the driven and driver components (i.e., gearboxes, pumps, rolls etc.,) within a tolerated margin. Alignment is accomplished by giving shimming or moving machine components or sometimes both. The aim of shaft alignment is to maintain a common axis of rotation at operating equilibrium for two coupled shafts.
In case of high speed equipment if the shaft alignment is not perfect we cant get maximum reliability and life through that equipment. Alignment is important in the case of direct coupled shafts and also the shafts of machines that are separated by distance even though we use flexible coupling. Shaft alignment is very important why because due to misalignment a lot of stress on shafts, vibration and noise produces. This causes excessive wear, bearing problems like heating and bearing failure, and results in the need for frequent repairs. By proper alignment we can reduce noise, vibration and also power consumption and this helps to achieve the design life of bearing, seal, shaft and coupling.
Alignment procedure is done by assuming a machine component is stationary, level and supported properly its base plate and foundation. Both angular and offset alignment must be performed in the vertical and horizontal planes, which is obtained by moving horizontally or by raising or lowering to align with the rotational center line of the stationary shaft. The movable components are designed as Machines To Be Moved (MTBM) or Machines To Be Shimmed (MTBS). MTBM generally refers to correction in horizontal planes and MTBS refers to corrections in vertical planes.