SHAFT
ALIGNMENT
Contents
Basic terms
What is shaft alignment
Why is shaft alignment so important
Types of alignment
Alignment methods
Alignment Tolerances chart
Causes of misalignment
Basic terms in shaft alignment
Co-linearity
Rotational centers
Misalignment
Stationary and Movable Machines
Horizontal and vertical misalignment
What is shaft alignment?
Shaft alignment is the positioning of the
rotational centers of two shafts such that
they are co-linear when the machines are
under normal operation.
Why is shaft alignment so important?
When shafts are misalign, forces are
generated in the coupling. Energy will be
lost and increased loads will be placed
on any mechanical components which
provide for rotation, seals, bearing
housing, etc
snap
Types of misalignment
Shaft alignment begin by defining two
types of misalignment:
1.Offset misalignment
2.Angular misalignment
Alignment methods
There are a wide variety of methods for
measuring alignment, the most common ones
are:
1.Mechanical method
2.Dial indicator method
a) Rim-Face method
b) Reverse Rim method
3.Laser method
Alignment Tolerances chart
RPM
3600
1800
1200
900
Angular misalinment
Mils/inch
0.001/1
Excellent
Acceptable
0.3
0.5
0.5
0.7
0.7
1
1
1.5
Offset misalignment
Mils
0.001
Excellent
Acceptable
1
2
2
4
3
6
4
8
Causes of misalignment
Increased vibration
Increased energy loss
Increased load on bearings, seals and
other mechanical components
Reduced production capacity
Reduced product quality
Vibration
Misalignment causes vibrations. Vibrations
are measured horizontally, vertically and
axially and there are some rules of thumb in
the analysis of the vibrations.
Horizontal vibrations indicate imbalance (H).
Vertical vibrations indicate a weak or loose
foundation (V).
Axial vibrations indicate misalignment (A)
Vibration
Alignment methods
Straight Edge
Reverse Rim
Rim-Face
Laser
Co-linearity
Two shafts are said to be co-linear when
their respective rotational centers form a
single line.
Rotational centers
All shafts, whether they are straight or bent,
rotate on an axis called the rotational center.
The rotational center forms a straight line.
Misalignment
Shafts are misaligned when their rotational
centerlines are not co-linear, when the
machines are operating.
Stationary and Movable Machines
When aligning any two machines, one is
designated as stationary and one as movable.
Horizontal and vertical misalignment
Horizontal Misalignment
Misalignment conditions viewed from the top and
corrected by sliding the front and back of the machine
from side to side are termed horizontal misalignment.
Vertical Misalignment
Misalignment conditions viewed from the side
(elevation) and corrected by making shim changes at
the front and back of the machine are termed vertical
misalignment.
Horizontal Misalignment
Vertical Misalignment
1.Offset misalignment
In shaft alignment, offset misalignment pertains
to the deviation of one shaft centerline from
another shaft centerline at a given point (or
plane) along the length.
2.Angular misalignment
Angular misalignment is most easily defined
as the slope relationship between two
rotational centers.
1.Mechanical Method
Straight edge/feeler gauge method:
Offset misalignment is measured using a
straight edge and set of feeler gauges.
Angular misalignment is measured by using
feeler gauges, taper gauges.
snap
Straight edges
Offset
Angular
2. Dial Indicator Methods
Rim-Face Method:
This was the standard method of alignment.
When using a rim-face method, one
measurement is taken on the rim of the
coupling to determine shaft offset. Another
measurement is taken on the face of the
coupling to determine shaft angularity.
Rim-Face Method:
Why is shaft alignment so important?
Forces generates
on coupling
Damaged seal
THANK
YOU
GHULAM MOHIUDDIN
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