On the use of the spectrum of the power cepstrum in the diagnostics of the rolling bearings

The present work was carried out to evaluate the efficacy of the Spectrum of the Power Cepstrum (SPC) in diagnosing faults in rolling bearings. Results were then compared with those from the envelope spectrum. The envelope method is at present believed to be the most effective instrument for diagnostics, in spite of its complexity of execution. After detailed examination of the characteristic properties of the SPC, some experimental tests were carried out on three different types of rolling bearings: a) in standard conditions; b) with a severe defect on the outer track; c) with a small defect on a sphere. The SPC shows the periodicity of the power cepstrum in the frequency domain, e.g., the family of harmonics produced by impulsive excitations, and attenuates only components due to mechanical and electrical noise. Experimental analysis on bearings with severe defects on the outer track showed that this new investigative tool is capable of identifying and diagnosing faults. Less striking results are obtained in the case of small defects on spheres, in which peaks related to defects are less visible. However, the very presence of faults is indicated by a reduction in amplitude of all the components of the SPC over the whole frequency domain.