Advanced Oil Condition and Debris Analysis

                      

Oil elemental analysis, oil quality characteristics, and debris

The specific oil quality contamination events that are the most dominant failure modes relevant to the target lubrication system are: water contamination, addition of incorrect oil, fuel dilution, and degraded oil. The current method of determining dominant failure modes in wear debris and oil quality is periodic oil sampling, and off-line testing, where the following standard  oil analysis tests are performed on oil4:

Elemental Analysis / Oil Debris

Atomic emission spectroscopy (AES) – wear debris and dirt

LaserNetFines (LNF) – silhouette of particle, plus size and shape

Ferrography – particle size and shape and sorted by ferrous / non-ferrous

Oil Quality

FTIR (bench and handheld) – lubricant condition and contamination

Viscometer – lube viscosity

Crackle test – water contamination

Karl Fisher – water contamination

Flashpoint – fuel contamination

Fuel meter – fuel contamination

Particle counting – for hydraulic cleanliness – fine particulate contamination

In order to realize a sensor that can enhance the timeliness and overall effectiveness of periodic oil sampling for corrective maintenance actions, the on-line sensor must provide data that is similar in concept or utility to many of these tests. 

Oil Debris Sensing

Oil debris is part of the end-of-life process of a mechanical component, such as a gearbox or oil-wetted bearing. The sensor must therefore be capable of correctly identifying the wear particulate produced by gear tooth wear or bearing spall. Correctly identifying the size and type of wear metals provides an indication of the component that is failing as well as the severity of the failure. Commercially available oil debris monitor (ODM) have been developed with consideration of these critical detection requirements.

An on-line inductive sensor typically detects nearly 100% of ferrous (Fe) and some non-ferrous (non-Fe) metallic wear debris particles above a minimum threshold size (typically 100-200 µm). The sensor counts each particle, determines particle makeup (Fe or non-Fe), and sizes the particles into bins (200-300 µm, 300-400 µm, etc.). The total mass of debris is updated in real-time. Size, count, mass, and makeup of wear particles have been shown to provide condition indication for aircraft bearings and provide diagnostic and prognostic information about bearing health and remaining useful life and allows for on-line discrimination of component damage vs. normal wear debris.

Additional Resources

Please check out some of my earlier publications on these capabilities at:

https://www.machinerylubrication.com/Read/138/real-time-oil-analysis

https://www.sbir.gov/node/5323

https://www.navysbir.com/06_1/123.htm

https://www.slideshare.net/Carl-Byington/cbm-sensing-by-carl-byington-of-phm-design 

About the Author:

Carl Byington developed and patented oil sensor technologies for Impact Technologies, Sikorsky Aircraft, and Lockheed Martin. Carl Byington became an expert in prognostics and health management (PHM) technologies and next-generation condition-based maintenance plus (CBM+) solutions. He currently consults in these technical areas at his PHM Design company, located in Georgia.