5.1 This guide is intended as a guideline for justification of oil test selection for monitoring rolling element ball type bearing conditions in industrial applications. Continuous benchmarking against similar applications is required to ensure lessons learned are continuously implemented.
5.2 Selection of oil tests for the purpose of detecting rolling element ball type bearing failure modes requires good understanding of equipment design, operating requirements and surrounding conditions. Specifically, detailed knowledge is required on bearing design configuration, dimensional tolerances, load directions, design limitations, lubrication mechanisms, lubricant characteristics, and metallurgy of lubricated surfaces including bearing cages. Equipment criticality and accessibility as well as application of other monitoring techniques (for example, vibration, ultrasound or thermal images) are also critical information in this analysis process. In addition, detailed knowledge on the lubricating oil is paramount.
5.3 To properly apply the FMEA methodology users must understand the changes the system may encounter during all operating modes, their impact on design functions and available monitoring techniques capable of detecting these changes. To assist this approach, Section 6 will provide extensive descriptions on the rolling element ball type bearing failure modes, their causes and effects.
5.4 It is recognized that in most industrial applications vibration monitoring is the primary condition monitoring technique applied to detect failure modes, causes and effects in rolling element ball type bearings—while oil analysis is primarily used to monitor the lubricating oil properties. In the recent years, however, there is a trend toward using oil analysis in order to provide earlier detection of some failures of rolling element ball type bearings. This is particularly applicable to complex dynamic systems such as compressors, gearboxes and some gas turbines where obtaining vibration spectra and their analysis may be more difficult.