Bearing analysis using SPM Spectrum™
The purpose of 'SPM Spectrum' is to verify the source of high shock pulse readings. Shocks generated by damaged bearings will typically have an occurrence pattern matching the ball pass frequency over the rotating race. Shocks from e. g. damaged gears have different patterns, while random shocks from disturbance sources have none.
Signal and measurement
The resonance frequency of the SPM shock pulse transducer, calibrated to 32 kHz, constitutes the ideal carrier wave for transients caused by shocks. The output of this transducer is the same type of demodulated signal produced by 'enveloping', with this important difference: both frequency and amplitude response of the SPM transducer are precisely tuned, so there is no need to find uncertain and shifting machine resonances to get a signal.
Input data
All pattern recognition requires precise data on the bearing and an exact measurement of the rpm. Finding a line or line pattern in a spectrum is a purely mathematical procedure where the rpm is one factor and the specified bearing frequency is the other. The rpm should always be measured, not preset. The factors defining the bearing frequencies are obtained by stating the ISO bearing number, linking to the bearing catalogue in Condmaster®Nova.
Evaluation
The frequency patterns of bearings are preset in Condmaster®Nova. Linking the symptom group 'Bearing' to the measuring point will allow the user to highlight a bearing pattern by clicking on its name. Other symptoms can be added when appropriate, e. g. for gear mesh patterns. Finding a clear match of a bearing symptom in the spectrum is proof that the measured signal originates from the bearing.