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2019 (English) In: Tribology Transactions, ISSN 1040-2004, E-ISSN 1547-397X, Vol. 62, no 5, p. 859-867Article in journal (Refereed) Published
Abstract [en] Machine maintenance is important for improving machine uptime, reliability, and reducing costs. Grease is used in most rolling element bearings, and one common failure criterion is water contamination, so developing a sensor which can detect water content automatically without human input could be a useful endeavor. The temperature dependence on the dielectric properties of water-contaminated grease is investigated in this paper with computer logged instrumentation. This method has been termed Dielectric Thermoscopy (DT). Several off the shelf (two lithium, one lithium complex, and two calcium sulphonate complex) and one unadditivized lithium grease are tested with varying amounts of water contamination from 0% to approximately 5%. Another grease is tested with small increments of added water from 0% to 0.97% to test the resolution of the measurement. The purpose is to use the capacitance temperature slope (termed dielectric thermoscopy) to show correlations to the water content of the grease sample and investigate if any grease types will pose problems in the measurement. A small, custom made fringe field capacitance sensor with an integrated temperature sensor has been used for this characterization and data is logged automatically with laboratory equipment and a PC. A useable and positive correlation to water content and the DT measurement of roughly 0.5 pF per 10 °C and percentage of water is found, although it was found that some greases have different behavior than others.
Place, publisher, year, edition, pages
Taylor & Francis, 2019
National Category
Other Mechanical Engineering Applied Mechanics
Research subject
Machine Elements; Experimental Mechanics
Identifiers urn:nbn:se:ltu:diva-75141 (URN) 10.1080/10402004.2019.1629051 (DOI) 000479625300001 () 2-s2.0-85073653107 (Scopus ID)
Note Validerad;2019;Nivå 2;2019-08-22 (johcin)
2019-06-282019-06-282025-02-14 Bibliographically approved