Page 212 - An Introduction To Predictive Maintenance

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TRIBOLOGY

Tribology is the general term that refers to design and operating dynamics of the
bearing-lubrication-rotor support structure of machinery. Several tribology techniques
can be used for predictive maintenance: lubricating oil analysis, spectrographic analy-
sis, ferrography, and wear particle analysis.

Lubricating oil analysis, as the name implies, is an analysis technique that determines
the condition of lubricating oils used in mechanical and electrical equipment. It is not
a tool for determining the operating condition of machinery. Some forms of lubricat-
ing oil analysis will provide an accurate quantitative breakdown of individual chem-
ical elements, both oil additive and contaminates, contained in the oil. A comparison
of the amount of trace metals in successive oil samples can indicate wear patterns
of oil-wetted parts in plant equipment and will provide an indication of impending
machine failure.

Until recently, tribology analysis has been a relatively slow and expensive process.
Analyses were conducted using traditional laboratory techniques and required exten-
sive, skilled labor. Microprocessor-based systems are now available that can automate
most of the lubricating oil and spectrographic analysis, thus reducing the manual effort
and cost of analysis.

The primary applications for spectrographic or lubricating oil analysis are quality
control, reduction of lubricating oil inventories, and determination of the most cost-
effective interval for oil change. Lubricating, hydraulic, and dielectric oils can be peri-
odically analyzed using these techniques, to determine their condition. The results of
this analysis can be used to determine if the oil meets the lubricating requirements
of the machine or application. Based on the results of the analysis, lubricants can be
changed or upgraded to meet the specific operating requirements.

In addition, detailed analysis of the chemical and physical properties of different oils
used in the plant can, in some cases, allow consolidation or reduction of the number

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