Using an Internal Trigger Source to Collect Data
dataPAC User’s Guide
159
The bump test helps you predict the natural frequencies of the machine. However, it is not a
quantitative test. It is just a quick and easy way to identify if natural frequencies are causing
the vibration problem.
If the machine’s vibration is the same as a natural frequency, the vibration level will be
enhanced by that harmonic vibration at the same frequency. This can cause problems
because the amount of natural vibration is added to the original vibration, so it becomes
amplified. Performing a bump test excites those natural frequencies, allowing you to
observe them, and find ways to reduce the harmonic effect. Often simply changing the
machine’s running speed will cause the harmonic effects to lessen.
To perform a bump test, follow these steps.
1.
Set up an internally triggered spectrum measurement on the dataPAC 1500.
2.
Press the <STORE> key so that the Set Trigger Level dialog box appears.
3.
Using a rubber mallet or a heavier hammer and a piece of wood (to protect the
machine), strike the machine.
4.
Watch the trigger levels and use the arrow keys to set the trigger level scale
accordingly.
5.
Choose OK when the trigger level is correct for the amount of vibration you observe
when striking the machine.
6.
Strike the machine again, which causes the vibration levels to go over the trigger level,
and the dataPAC starts collecting data.
7.
You can store and analyze the measurement in the dataPAC.
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com
