Vibrations and Absorption

If a machine is showing high vibration damping may quieten it down but the problem is still there. If your proposing damping around the outer race it would make matters worse as the both inner and outer race would be vibrating.

This is not a permanent solution. It is a good practice to replace the over vibrated bearings as per the PPM schedule. If the failure of bearing is frequent you need to carry out the root cause analysis to find out the reason for its frequent failure.

The whole idea of a Preventative Maintenance is to prevent unplanned downtime and Vibration analysis is one tool in the process. Why would anyone in their right mind like to camouflage a red flag (high vibrations) by adding dampeners and sound absorbers.

It is a different story, if this is a study to gauge the effectiveness of such devices. There are industrial coatings to dampen sound but vibrations?? I am not aware of. Would you be doing this in a lab or real operational machines?

"why cant we provide an extra coating for the respective machine for absorption of over vibration.If so means which material is suitable for absorption of over vibrations"

Extra coating (like paint etc.) will not help to reduce shaft vibration and so to save the bearings.

Vibration of different parts of the system also generate noise. Accaustic insulation (consisting materials such as mineral wool etc.) on the outer surface of the vibrating parts like equipments and piping is used for noice attunuation. This is nothing but dampening the vibration amplitude to reduce noice. Accaustic insulation should not be used for dampening the bearing vibration.

We need a little more info on these machines. When I analyze, I ask 6 basic questions to help break down the machine vibration symptoms.

1) what is the predominate frequency? In the machine, which vibration frequency has the highest amplitude? 80% of the time, this is your problem.

2) what other significant frequencies are present? are these harmonics,sidebands,mounds/lumps, raised noise floor or none of the above? what shape of motion makes these patterns? No harmonic pattern is smooth or sinusoidal motion. this includes 1x,1x & 2x only, 1x & 3x only and 1x 2x 3x only. Odd harmonics only is square or triangluar motion. Odd and even harmonics is impactive or pulse type motion. Mounds/Lumps, random shape is usually due to flow turbulence, cavitation or looseness. Volcano shaped is usually a natural frequency amplification region. Raised noise floor. The most common source is large random events,such as severe looseness or process events.

3) can i isolate to one shaft of bearing?

4) is the horizontal amplitude or vertical amplitude 4x bigger than the other?

5) is the axial amplitude >50% of the highest radial amplitude? If the axial amplitude is more that half of the largest radial amplitude, the machine has an axial problem. if the axial amplitude is less than half of the largest radial amplitude, the machine has a raidal problem.

6) do i need phase?

if the answer to question #1 is 1x rpm then #6 is always yes.

if the answer to #1 is 2x rpm or 3x rpm the answer may or may not be yes.

if more than one problem is still possible after the answers to questions 1-5 than the answer is yes. if only one problem is possible the answer is no.

as you can see theres alot more information you can tell us, but i hope this helps.

GA.