MIS-ALIGNMENTS:
Shaft misalignment occurs when the centerlines of rotation of two (or more)
machinery shafts are not in line with each other -In more precise terms, shaft
misalignment is the deviation of relative shaft position from a collinear axis
of rotation measured at the points of power transmission when equipment is
running at normal operating conditions.
TYPE OF MIS-ALIGNMENTS:
- ·Offset or Parallel misalignment - Occurs when the two shaft center lines are parallel, but not in the same line. They are offset horizontally or vertically (or both), displaced to the left or right, or positioned at different elevations.
- Horizontal offset misalignment
- Vertical offset misalignment
- Angular misalignment- The axis of Driven and Driver shaft are at an angle to each other.
- Vertical angular misalignment
- Horizontal misalignment
- Combination misalignment- Occurs when the motor shaft suffers from angular misalignment in addition to parallel misalignment.
ANGULAR MISALIGNMENT:
SYMPTOMS OF MISALIGNMENT:
- Premature bearing, seal, shaft, or coupling failures.
- Excessive radial and axial vibration.
- High casing temperatures at or near the bearings or high discharge oil temperatures.
- Excessive amount of oil leakage at the bearing seals.
- Loose foundation bolts.
- Loose or broken coupling bolts.
- Excessive amount of grease on the inside of coupling guard
- Similar pieces of equipment are vibrating less or seem to have a longer operating life.
- Unusually high number of coupling failures or they wear quickly.
- The shafts are breaking (or cracking) at or close to the inboard bearings or coupling hubs.
- Excessive amounts of grease (or oil) on the inside of the coupling guard.
TIR -
Total Indicator Reading: Total range of a dial indicator reading when
gauging misalignment.
Shaft Run out
is the wobble motion produced by a shaft that is not perfectly true and straight.
Shaft run out is often abbreviated T.I.R. (Total Indicated Run out).
PREREQUISITE OF ALIGNMENT:
- Dial gauge mounting clamp.
- Single dial gauge mounting clamp.
- Double dial gauge mounting clamp.
- Spanner set.
- Dental or plane mirror.
- Filler gauge.
- Pre cut shims.
- Measuring tape.
- Jacking bolts.
- Scale.
- Micrometer.