Advanced condition monitoring of tapered roller bearings, part1

Abstract

A new condition monitoring technique is under development which is based
on electrostatic charge. This was originally employed for the detection of debris in the
gas path of jet engines and gas turbines, and is now being developed for lubricated
systems. Previous investigations have demonstrated the viability of this technique in
dry and lubricated tribo-contacts using laboratory-based equipment. This paper
reports on the evolution of wear during a tapered roller bearing test, using a suite of
condition monitoring techniques, that incorporated electrostatic wear-site sensors to
identify charge during surface wear and oil-line sensors to detect debris in oil
scavenge lines. The multi-sensor arrangement also included a vibration accelerometer,
thermocouples, inductive and ferromagnetic particle counters. Additionally, oil
samples were taken during various stages of the test and were analysed for sub-100
?m debris content. Off-line debris analysis included optical particle counting,
ferrography, spectrometric oil analysis and electron microscopy. Further tribological
assessments included mass loss calculations and photographic evidence of damage.
During the initial 7 hours, running-in wear was identified by dynamic wear site
charge, acceleration and temperature. Also at this time, increases in oil-line charge
correlated with debris detection by the inductive sensor, optical particle counter and
ferrographic analysis. Following running in, benign wear was indicated by a reduction
in wear site charge, acceleration and temperature, as well as reductions in oil-line
charge, inductive and optical particle counts. Around 42 hours, increases in inductive
and optical particle count were considered to be an early indicator (or precursor) of
the impending wear out phase. At 53.5 hours, wear out was identified by increases in
wear site charge, acceleration and temperature. Evidence of wear debris was shown
by increases in oil-line charge, inductive and ferromagnetic particle count. The debris
was further corroborated by optical particle count, ferrography and spectrometry. The
test was then stopped after 63 hours and post-test analysis confirmed outer race and
roller spallation.

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Identifiers

ORCID for R. J. K. Wood: orcid.org/0000-0003-0681-9239

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