The application of the HFRT (High-Frequency Resonance Technique), a demodulation based technique, is a technique for evaluation the condition of bearings and other components in rotating machinery. Another technique MED (Minimum Entropy Deconvolution) has been the subject of recent developments for application in condition monitoring of gear trains and roller bearings. This article demonstrates the effectiveness of the combined application of the MED technique with HFRT in order to enhance the capacity of HFRT to identify the characteristic fault frequencies of damaged bearings by increasing the signal impulsivity. All tests were done using data collected from an experimental test bench in laboratory. The Kurtosis value is used as an indicator of effectiveness of the combined technique and the results shown an increase of five times the original kurtosis value with the application of MED filter together with the HFRT.

Nowadays the method based on demodulation by envelope finds wide application in industry as a technique for evaluation of bearings and other components in rotating machinery. In recent years the application of Wavelets for fault diagnosis in machinery has also obtained good development. This article demonstrates the effectiveness of the combined application of Wavelets and envelope technique (also known as HFRT High-Frequency Resonance Technique) to remove background noise from signals collected from defect bearings and identification of the characteristic frequencies of defects. A comparison of the results obtained with the isolated application of only one method against the combined technique is performed showing the increased capacity in detection of faults in rolling bearings.