July 23, 2015
Using the AlignHot App (Hot Check) to Determine Thermal Growth Targets
By Brad Case
A previous blog of mine discussed the benefit of taking a set of hot alignment readings to verify if the offset targets used for a cold alignment, to compensate for thermal growth (dynamic movement), were correct. http://thealignmentblog.com/blog/2015/04/15/benefit-hot-alignment-check/
So what if the actual hot alignment readings you get show a large difference from the anticipated hot position? In other words, the cold alignment targets used were incorrect and now that the machine is up to operating temperature it is misaligned.
Well, we have an App for that and it’s free! The VibrAlign HotAlign App (also called Hot Check) allows the user to easily determine the vertical AND horizontal targets needed to compensate for dynamic movement when aligning the machine at ambient temperature. (The Fixturlaser NXA Pro/Ultimate comes with the Hot Check App/Program).
First, save the “Cold” and “Hot” alignment results in your laser shaft alignment system. NOTE: The HOT alignment measurements need to be taken fairly quickly before the machines cool down, otherwise you are not measuring the true Hot machine position.
Open the AlignHot APP on your smart device..
When the App opens select English or Metric measuring units then press the Blue Thermometer button
at the bottom of the screen and enter the vertical and horizontal coupling values from your saved COLD shaft alignment results into the App. making sure to enter the correct signs for each coupling value.
Then press the RED Hot Thermometer button and enter the vertical and horizontal coupling values from your saved HOT shaft alignment results into the App. making sure to enter the correct signs for each coupling value.
As Thermal Growth (Dynamic Movement) is movement of rotating machinery from the Cold position to the Hot position then the Targets are calculated by subtracting the Hot position from the Cold position.
Press the COLD – HOT Thermometer Button and the APP does this calculation for you.
These Target Coupling Values are entered into the Fixturlaser Laser Alignment System for the Cold Alignment. Once entered into the alignment system the system bases all results and correction information off of the inputted targets as is indicated by the RED thermometer in the upper right hand corner of the screen.
For those performing precision shaft alignments you now have 3 options at your disposal to determine cold alignment targets for machines with thermal growth or dynamic movement.
Good – The free VibrAlign Therm Align App. (thermal growth calculator) http://acoem.us/tools/mobile-apps/
Better – The free VibrAlign AlignHot App. http://acoem.us/tools/mobile-apps/
Best – The optional OL2R (OffLine to Running) Program and brackets for the Fixturlaser NXA Pro/Ultimate (allows hot measurements to be taken while the machine is running. http://acoem.us/tools/shaft-alignment/ol2r-fixtures-software/
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