Test & measurement


Solving the problem of alignment with high vibration


In this article, Nexxis provides some tips on using laser alignment tools to achieve more accurate readings in situations with high vibration


O


ne of the most common issues when doing alignments in an environment where other machines are operating


nearby is that there may be high vibration from the adjacent equipment. In such cases (which happens often), it becomes nearly impossible to ascertain repeatability. Let us say a dial indicator was being used to


take measurements of a machine that was moving several thousandths as a result of the vibration. In all likelihood, the indicator needle would oscillate between around 35 and 42 so the technician would have to make an educated guess as to the measurement and would probably settle for 38 or 39 as the average midpoint. However, a laser alignment tool can be


used to achieve more accurate readings in situations of high vibration. Here are some tips as to how to go about using one of these devices in such situations:


1 2


Instead of using the fully automatic measurement mode, a much better option is to switch the device to one of


the manual measure modes.


When the device is in a manual mode such as Multipoint, it is possible to adjust the sampling time


for each reading. These settings allow you to take a little more time taking each point which in turn, enables more data to be collected at each measurement position. Unlike the guesswork when using a dial indicator, a laser alignment tool enables far more accurate averaging.


3 24


Even though the minimum number of positions over 700 is five, you should take at least eight positions


around the 3,600 of rotation. The more points


and the more rotation that you have, the more accurate your results will be.


4


If the repeatability is not satisfactory, you should check your standard deviation values. These should be very


low, so if they are too high, then it is likely that the averaging has not been set high enough to account for the vibration issues from surrounding machinery.


5


More haste, less speed. If you rush through readings, you may end up with inaccurate results which will take even


longer to correct. If you cannot get repeatable numbers, rather take longer over the readings and make sure they are accurate.


6


In situations of high vibration, the ‘Live Move’ setting may also be problematic. A solution is to ensure


that the averaging value for the Move function is the same as the one with which successful readings were taken. In this situation, it may


take longer for the results screen to update but be patient because by doing this, you will steady the ‘Move’ and accuracy will be significantly improved.


7


A quality laser alignment tool is an invaluable asset for keeping moving machinery operating optimally, but


technicians always need to be cognisant of vibration from other equipment nearby and compensate if necessary.


8


Running a repeatability test at the beginning of the alignment only takes a few minutes, but it can save hours and


avoid frustration in the long run. You should always get advice from an


industry expert before making any final decisions on a laser alignment tool to make sure you get the most appropriate model for your needs. A wide range of leading brands of laser alignment devices are available for purchase or hire in Australia from Nexxis, and they back-up every hire contract or equipment sale with specialised, practical advice from qualified technical experts.


Nexxis nexxis.com.au November 2018 Instrumentation Monthly


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