Bearing Defect Frequencies and Running Speed

Hello,

Most vibration analysis software have bearing defect frequency markers build into them, where you select the bearing and the fault frequencies are automatically matched. 

I also see that many software have these defect frequencies in Hz and Not Orders. (Eg: SKF NU 216 Bearing have 2.75 Hz as FTF, 22.9 Hz as FTF Also). And it appears to be a constant.

So is bearing defects not related to running speeds? (Eg. NU 216 Bearing can be running at different speeds in different machines). Shouldn't the bearing frequency markers be set according to running speed and in Orders of 1X rather than set frequencies ?

Thank you in advance. Would appreciate your feedback on this.

 

Nitheesh

Original Post
Nitheesh posted:

Hello,

Most vibration analysis software have bearing defect frequency markers build into them, where you select the bearing and the fault frequencies are automatically matched. 

I also see that many software have these defect frequencies in Hz and Not Orders. (Eg: SKF NU 216 Bearing have 2.75 Hz as FTF, 22.9 Hz as FTF Also). And it appears to be a constant.

So is bearing defects not related to running speeds? (Eg. NU 216 Bearing can be running at different speeds in different machines). Shouldn't the bearing frequency markers be set according to running speed and in Orders of 1X rather than set frequencies ?

Thank you in advance. Would appreciate your feedback on this.

 

Nitheesh

Certainly bearing fault frequencies are related to running speed and on most software or bearing databases you have the ability to input rotor speed as well as whether the inner race is rotating or held.  When you input rotor speed, the result for the frequencies is often in Hz.  But if you do not enter rotor speed, then the output is in orders and you must do the conversion.

John from PA posted:
Nitheesh posted:

Hello,

Most vibration analysis software have bearing defect frequency markers build into them, where you select the bearing and the fault frequencies are automatically matched. 

I also see that many software have these defect frequencies in Hz and Not Orders. (Eg: SKF NU 216 Bearing have 2.75 Hz as FTF, 22.9 Hz as FTF Also). And it appears to be a constant.

So is bearing defects not related to running speeds? (Eg. NU 216 Bearing can be running at different speeds in different machines). Shouldn't the bearing frequency markers be set according to running speed and in Orders of 1X rather than set frequencies ?

Thank you in advance. Would appreciate your feedback on this.

 

Nitheesh

Certainly bearing fault frequencies are related to running speed and on most software or bearing databases you have the ability to input rotor speed as well as whether the inner race is rotating or held.  When you input rotor speed, the result for the frequencies is often in Hz.  But if you do not enter rotor speed, then the output is in orders and you must do the conversion.

Thank you so much for the information.

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