Transcript Measuring Positional Change

MEASURING
POSITIONAL CHANGE
By LUDECA, INC.
Positional Change
 After startup, machines grow warmer or colder, undergo thermal
gradients, and may suffer dynamic load shifts.
 This may cause their shaft centerlines to move from the position
they were in when stopped.
 Therefore, a good shaft alignment done when cold and stopped
may result in a poor alignment when the machines are running
and under load!
Do you need to know if this is happening
to your machines?
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Objectives
 Your objective is to find out if your machines move between the
stopped condition and the running condition, in order to
establish good alignment targets.
 The machines can then be misaligned to these alignment
targets when ‘cold’ and stopped to compensate for the
measured change.
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Understanding what you need
Measurement allows you to compare data at two different
points in time with no knowledge of the intervening events which
may impact the data.
Monitoring allows you to establish the trend of a change over
time and observe the influences of given events.
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Determining Positional Change
There are several ways to determine positional change.
We will only discuss the following four:
 Calculating the changes theoretically from the observed
changes in temperature using the “TLC” method.
 Checking the difference in the results from two separate
rotational readings on the shafts, both taken stopped, one
“cold”, and one right after shutdown “hot”. This is the so-called
“Hot Alignment Check”.
 Measuring the change with two separate rotational readings
with special brackets mounted on the bearing housings, one
taken hot and running, one taken cold and stopped, using the
M3 (Measuring Machine Movement) Brackets.
 Monitoring the change continuously with PERMALIGN®.
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The “TLC” calculation method
The “TLC” method only looks at the theoretical projected growth
from changes in temperature.
TLC = T × L × C, where:
T =  in Temperature, L = Length, C = Coefficient of Expansion
 Positional shifts due to dynamic load are not considered.
 Cooling influences of fans, and influences on machine shape of
thermal gradients from process flows are not considered.
 Unless specifically factored in, the expansion or contraction of
connected piping will not be considered.
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The “hot alignment check”
The ‘hot check’ results will not be the same as that of the
running machines because the machines are not running!
 Positional shifts due to dynamic load are gone.
 Too much time will elapse in locking out the machines, removing
the coupling guard, setting up the system and taking readings.
The temperature is quickly changing from what it was when the
machines were running, so they are contracting or expanding,
changing the alignment.
 Process flows and cooling fans have stopped. This means
thermal gradients have shifted, again changing the shape of the
machines and their alignment. The same may apply to
connected piping.
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The M3 Bracket
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The M3 Brackets
The M3 Brackets can be used with:
ROTALIGN®/PRO, SMARTALIGN®, OPTALIGN® PLUS and
MASTERLIGN®/BASIC Laser Shaft Alignment Systems
The M3 (Measuring Machine Movement) method:
 Mount the M3 brackets on the bearing housings of the machines.
 Take a rotational reading when machines are cold and stopped.
 Take another while they are running under load.
 Compare the results. Any difference means positional change
may have taken place.
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Measuring with the M3 Brackets
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M3 Brackets – Limited Monitoring
Limited Continuous Monitoring with
ROTALIGN®/PRO:
 If conditions are stable, ROTALIGN®/PRO allows you to
monitor positional change continuously in both planes with its
Move Function, because of its unique five-axis sensor.
 This capability eliminates the need to take rotational readings
and remove and replace the components between the hot and
cold readings, helping to control data quality.
 You can also store and annotate the data in the
Measurement Table.
 Adjustable averaging in the Move Function helps limit the
influence of vibration and heat on the readings.
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PERMALIGN®
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Why monitor with PERMALIGN®?
PERMALIGN® is the only laser-based positional change
monitoring system.
 Quality assurance of data.
 Completeness of data.
 Trending of data over time.
 Full documentation capability.
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PERMALIGN®’s unique features
 PERMALIGN®’s patented concentric reflected beam technology
is impervious to any influence on beam movement from heat
waves or particles in the path of the beam.
 Its components are thermally stable. They will not distort with
temperature changes, so the beam will not be moved.
 The laser transducer and prism are specifically designed to
withstand heat and vibration over time.
 PERMALIGN® permits you to establish precisely which machine
is moving, how much and which way.
 In the event any bracket movement occurs, you can determine
this from the data collected and trended with WINPERMA®
software and correct for it.
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What about extreme heat?
PERMALIGN® components
can be air-cooled or cooled by
running tap water through
cooling tubes.
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