Use of electrostatic charge monitoring for early detection of adhesive wear in oil lubricated contacts

Electrostatic charge sensing technology has been used to monitor adhesive wear in oil lubricated contacts. Previous work in this area demonstrated that "precursor" charge events may be detected prior to the onset of scuffing. Possible charging mechanisms associated with the precursor events were identified as tribocharging, surface charge variation, exo-emissions and debris generation. This paper discusses the proposed charging mechanisms and details a series of investigative tests using an adapted pin-on-disc (PoD) rig. The PoD tests focused on surface charge variation effects and were of two types, non-contact, where different materials were inserted it? the disc, and controlled scuffing tests.