Oil & Wear Debris Analysis Techniques

Wear debris analysis is the means by which wear particles generated during machine operation are identified and used to determine the condition of machines. Common events contributing to the addition of wear particles include maintenance procedures, oil top-offs and oil changes. They are often caused by contamination, inappropriate lubrication, environmental changes in operating conditions and other situations that result in metal-on-metal contact.

Direct Reading Ferrography

This wear debris analysis technique is designed to differentiate between large and small ferrous particles in a given machine. Here, large is defined as more than 5 microns, and small is defined as smaller than 5 microns. Analysts use this information to determine whether normal wear is taking place. If there is an abnormal increase in particle size, the machine should be inspected for quality.

Analytical Ferrography

This wear debris analysis technique employs a detailed microscopic analysis of solid particles found in a sample of oil. In this approach, particles are analyzed to determine whether they are ferrous or non-ferrous. Particles analyzed include iron, fibers, sand and dirt among others. If there is too much ferrous material in the sample, analysts identify the abnormal wear mode of the system, which aids in identifying the specific problem with the machine and when it is likely to fail.

Laserview

This wear debris analysis technique is typically used in conjunction with traditional oil analysis techniques to determine whether there are any severe wear conditions. Laser imaging is employed in order to identify, classify and measure the type of mechanism responsible for the wear, the sizes of particles, how the particles are distributed throughout the oil sample and the particle count.

Filter Patch Test

The Filter Patch Test relies on the examination of wear particles under a microscope. A sample of oil is filtered through a filter patch, which is then examined so analysts can produce a particle report.

Particle Quantifier Index

A particle quantifier is a magnetometer that is designed to measure the mass of iron wear debris in an oil sample. This results in a certain Particle Quantifier Index rating, which provides information on how much wear is taking place within a machine. This approach is considered simple and cost-effective.

References

• ALS Global: Wear Debris Analysis