Part 2, Wear Severity Classification

Wear Particle Atlas CD-ROM

The Wear Severity Classification feature is one of four parts of theWear particle Atlas CD-ROM. It provides an exclusive filtergram-based wearseverity differentiation component which embraces 456 images and over 100application cases in order to differentiate machine wear severity levelswith improved consistency. The wear severity levels are divided into either10 levels (from Level 1 to Level 10) or 8 levels (Level 3 to Level 10).Each characterizes wear deterioration from initial wear to severe wear.An example for cutting wear particles is shown below.

Example of Cutting Wear Severity Index

To be objective in its differentiation, the Atlas first defines the "keyfeatures" for each severity level. This is the quantitative, measurablecriterion based on the size distributions and wear-mode-related type distributionsof the wear particles. Second, the Atlas provides 1-5 wear cases at eachseverity level that approximately meet the criteria of the designated severitylevel. Each example consists of 4 representative wear particle images. Bymatching both measurable criteria and visible images, a random wear particlesample can be coded with a certain severity level number. For example, themetal particles in an oil sample are:

The quantitative features of this sample meet the criteria for Level6 of the fatigue wear severity. Further, the features of the wear particlesof this sample are equivalent or similar to those of the examples (cases)in the Atlas. Therefore, the wear severity level of this oil sample canbe differentiated as 6.

As can be seen from the example below, the criteria of fatigue wear severitylevel 6 is:

Example of Fatigue Wear, Severity Level 6

This differentiated Level 6 is a universal wear severity level. It canbe defined as a "normal", or an "abnormal" or even acatastrophic condition. The determination depends on the criticality, operationalenvironment, and expected life of the machine from which the particles came.For example, if this sample came from a large slow rolling bearing, thisseverity level 6 may be defined as a "mildly abnormal" wear condition.However, if this sample came from a critical gear system, this Level 6 maybe specified as an "unacceptable" or even a "severe"condition. It is from this perspective that the wear severity differentiationin the Atlas provides an approximate yardstick for measuring machine severity.This enables an activity, which currently is subjective, to be quantitativeand standard.

Thank you for visiting the "Wear Severity Classification"feature of the Wear Particle Atlas CD-ROM. Additional features can be reviewedby returning to the Wear Particle Atlas CD-ROM FeturesIndex.

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