3x vibration

[ksener]

In fixed bearing's horizontal velocity specktrum 3X is ~0.75 x 1X and time wave form is typical alignment problem but after balancig of fan 3X and alignment timewave form are lost. What may be the problem?

 

[DePauw]

Hello Ksener

I think looseness is the problem.
You chech it like this : put a clock-meter ( 0.01mm) on the axis and lift the ventilator with a jack, 0.05 mm is normal, 0.1 mm is still good, 0.2mm or more is bad.

Good luck
DePauw

 

[ksener]

Hi,
Looseness from which points? Can we disturb the time waveform of losseness by balancing?
Does clockmeter values depens on the bearing type and shaft diameter. I think it has to be.
In the campaign i will measure that values.
Thank you

 

[bulldawg]

ksner,

In my experience it is not unusual for harmonics to show up in cases of severe unbalance.

The unbalance was likely inducing enough energy into the fan? to exagerate any looseness in the machine ie. bearings, base, duct work, piping, motor covers, gaurds etc.

The 3X vibration is probably the location of a resonant frequency, and after balancing the forcing frequency disapeared and thus the 3X.