Resistivity, an Online Monitoring Parmeter for Antifriction Bearings : An Experimental Investigation

The condition monitoring of rolling element bearings is becoming critical with advancement of technology. The existing major monitoring methods such as Vibration Signature Analysis, Acoustic Emission Measurement, Measurement of lubricant film thickness using Ultrasound Transducer or Strain Gages, Interferometric measurement of lubricant film thickness, etc. are either expensive or applicable after some wear has been set in or cannot be used for online condition monitoring of antifriction bearings. There always exists a possibility for development of a condition monitoring method which is simple, inexpensive and reliable. Keeping this in view, a new methodology has been developed for determination of lubricant film thickness based on Hertz contact theory. The formula for lubricant film thickness requires electrical resistivity of lubricant as one of the parameter. Thus, an inexpensive experimental setup is developed for determination of electrical resistivity of liquid lubricants and the results are validated in the work. The proposed method shows variation of lubricant film thickness during operation of bearing thus can be used for Predictive Online Condition Monitoring.