When performing a Dynamic Balance procedure a few things should be considered:

1.  Inspect the structure/mounts and ensure there are no cracks or loose bolts.

2.  If driven via a belt drive make sure that the belt is in good condition and properly tensioned.
• Remember that the second harmonic of a belt frequency can be very close to the rotational speed of the drive.

3.  Inspect the rotating element for the build-up and clean as necessary.
• Remember that even slight build-up (i.e., dust) can be the cause of an unbalance.

4.  If the rotating element is a blower, count the number of blades.
• Frequently correction weights will have to be attached to the blades and therefore it may be best to use a fixed location method.

5.  If the equipment is down when you arrive, replace the reflective tape or attach new tape as may be required.
• This will ensure accurate phase data.

6.  When taking your initial phase data turn the averaging function off, if possible.
• Monitor the phase data for a brief time to ensure its stability. Doing this could identify potential problems.

7.  Keep good documentation, keep written notes on what was found:
a.  Phase and amplitude data
b.  Number of blades
c.  Correction locations
d.  When weights were attached or removed
e.  How much weight was attached or removed
f.  Sensor placement
g.  Tachometer placement.

8.  If the equipment is variable speed such as VFD drive or DC drive ensure that the speed is repeatable to within 5% or less run to run.

Filed under:
, by Gary James CRL