bearing tester results meaning 1

[spike]

We have received some bearing tester data that was taken on our fan bearing. The readings were in the dbm 40 & dbc 21 range. dbm was defined as max shock value in decibels, and dbc as average shock value in decibels.

I do not know what "tester" was used.

I do not have a clue as to what these values mean, does anyone have an opinion? I wonder what levels would be classified as normal and what levels would indicate a problem.

 

[ischgl99]

The numbers you give appear to be from the Timken "Shock Pulse" measuring method and cannot be correlated to any particular standards. The dBm is a meaurement of the impacting occuring in the bearing, other companies such as FAG Industrial Services and CSI use envelope demodulation to measure the same thing, but the units are different and it is very difficult to compare one to the other.

The best way to determine if you have a bearing problem is to analyze the spectrum and trend the data and look for changes, then you can set your limits as to what is acceptable. For your fan, these numbers may be perfectly acceptable. Did they just give you these single readings or do you also have a spectrum that shows any faults or have you done any trending? If you have the spectrum, then you can check the individual bearing fault frequencies and look for spikes that will indicate any problems. If you have been trending and the levels have remained fairly consistant, then those levels probably are ok.

 

[Strong]

Spike,

My guess is that a Shock Pulse Meter (SPM) was used for the measurements. Here is a link to an explanation of the data:

http://www.spminstrument.com/solutions/methods/spm.asp

Walt