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MEASURINGMEASURINGPOSITIONAL CHANGEPOSITIONAL CHANGE
MEASURINGMEASURINGPOSITIONAL CHANGEPOSITIONAL CHANGE
By LUDECA, INC.
www.ludeca.com
Positional ChangePositional ChangePositional ChangePositional 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 Do you need to know if this is happening to your machines?to your machines?
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ObjectivesObjectivesObjectivesObjectives
Your objectiveobjective is to find out if your machines move between the stopped condition and the running condition, in order to establish good alignment targetsalignment 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 needUnderstanding what you needUnderstanding what you needUnderstanding what you need
MeasurementMeasurement allows you to compare data at two different points in time with no knowledge of the intervening events which may impact the data.
MonitoringMonitoring allows you to establish the trend of a change over time and observe the influences of given events.
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Determining Positional ChangeDetermining Positional ChangeDetermining Positional ChangeDetermining Positional Change
There are several ways to determine positional change. We will only discuss the following fourfour:
CalculatingCalculating the changes theoretically from the observed changes in temperature using the “TLC” method “TLC” method.
CheckingChecking 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”“Hot Alignment Check”.
MeasuringMeasuring the change with two separate rotationalrotational readings with special brackets mounted on the bearing housings, one taken hot and running, one taken cold and stopped, using the MM33 ( (Measuring Machine MovementMeasuring Machine Movement) Brackets) Brackets.
MonitoringMonitoring the change continuously with PERMALIGNPERMALIGN®®.
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The “TLC” calculation methodThe “TLC” calculation methodThe “TLC” calculation methodThe “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 alignment check”The “hot alignment check”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 MThe M3 3 BracketBracketThe MThe M3 3 BracketBracket
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The MThe M33 Brackets BracketsThe MThe M33 Brackets Brackets
The MThe M33 Brackets can be used with: Brackets can be used with:
ROTALIGNROTALIGN®®/PRO, SMARTALIGN/PRO, SMARTALIGN®®, OPTALIGN, OPTALIGN®® PLUS and PLUS and MASTERLIGNMASTERLIGN®®/BASIC /BASIC Laser Shaft Alignment Systems
The MThe M33 (Measuring Machine Movement) method: (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 MMeasuring with the M33 Brackets BracketsMeasuring with the MMeasuring with the M33 Brackets Brackets
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MM33 Brackets Brackets –– Limited Monitoring Limited Monitoring MM33 Brackets Brackets –– Limited Monitoring Limited Monitoring
Limited Continuous Monitoring with Limited Continuous Monitoring with ROTALIGNROTALIGN®®/PRO/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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PERMALIGNPERMALIGN®®PERMALIGNPERMALIGN®®
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Why monitor with PERMALIGNWhy monitor with PERMALIGN®®??Why monitor with PERMALIGNWhy monitor with PERMALIGN®®??
PERMALIGNPERMALIGN®® is the onlyonly laser-based positional change monitoring system.
Quality assuranceQuality assurance of data.
Completeness of data.
Trending of data over time.
Full documentation capability.
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PERMALIGNPERMALIGN®®’s unique features’s unique featuresPERMALIGNPERMALIGN®®’s unique features’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?What about extreme heat?What about extreme heat?What about extreme heat?
PERMALIGN® components can be air-cooled or cooled by running tap water through cooling tubes.
