"Database of wear and contaminant particles in used lubricants."
Introduction The Wear Particle Atlas CD-ROM is a new comprehensive computer database
of wear particles found in all types of oil lubricated equipment. It combines the
traditional ferrogram techniques with the more recent filtergram technique and contains
close to 1,000 color pictures with detailed descriptions. The combined use of both
ferrogram and filtergram methods has improved the reliability of failure prediction
for both ferrous and nonferrous components and thus maximizes the strengths of microscopic
wear particle analysis.
The Wear Particle Atlas CD-ROM is designed to:
Assist the professional laboratory engineer to identify wear particles and to analyze
machine wear conditions.
Assist plant lubrication engineers to keep equipment in their best operational order
based on the wealth of information contained in the lubricant wear debris.
Wear Particle Atlas CD-ROM Features Index The Wear Particle Atlas CD-ROM main features
Part 1, Picture Guide
The Picture Guide is one of four main features of the Wear Particle Atlas CD-ROM.
It helps to locate the relevant or matching Atlas page by allowing the user to compare
the main characteristics of the sample micrograph with those of the Atlas pictures.
A total of 14 Image Guide pages are available to aid in the particle type identification
When Atlas is first started, the Home Page as shown on the right appears. On this
page there are 8 wear particle images which are representative of 8 sub-categories,
By clicking each image, the corresponding sub-category page will appear.
The sub-category contains representative particle images depicting additional sub-categories
that can be clicked until the Browsing Atlas page is displayed and the correct particles
are found. The following example illustrates this process. On the Picture Guide Home
Page, select "Nonferrous Materials". The Picture Guide Page, "Nonferrous Materials"
as shown below will appear. Select "Copper-Ferrogram" and the Browsing Atlas Page
for copper particles will appear. It contains several sets of copper ferrogram pictures.
Part 2, Wear Severity Classification
The Wear Severity Classification feature is one of four parts of the Wear Particle
Atlas CD-ROM. It provides an exclusive filtergram-based wear severity differentiation
component which embraces 456 images and over 100 application cases in order to differentiate
machine wear severity levels with 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 "key features"
for each severity level. This is the quantitative, measurable criterion based on
the size distributions and wear-mode-related type distributions of the wear particles.
Second, the Atlas provides 1-5 wear cases at each severity level that approximately
meet the criteria of the designated severity level. Each example consists of 4 representative
wear particle images. By matching both measurable criteria and visible images, a
random wear particle sample can be coded with a certain severity level number. For
example, the metal particles in an oil sample are:
ferrous fatigue wear particles;
the size of the fatigue wear particles is up to 100 µm, and
the concentration of the fatigue wear particles ranging between 50-100 µm in size
The quantitative features of this sample meet the criteria for Level 6 of the fatigue
wear severity. Further, the features of the wear particles of this sample are equivalent
or similar to those of the examples (cases) in the Atlas. Therefore, the wear severity
level of this oil sample can be differentiated as 6.
As can be seen from the example below, the criteria of fatigue wear severity level
Up to 100 µm in size;
Predominant laminar particles; and
Concentration of laminar particles ranging between 50-100µm are greater than 100/ml
Example of Fatigue Wear, Severity Level 6
This differentiated Level 6 is a universal wear severity level. It can be defined
as a "normal", or an "abnormal" or even a catastrophic condition. The determination
depends on the criticality, operational environment, and expected life of the machine
from which the particles came. For example, if this sample came from a large slow
rolling bearing, this severity 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 differentiation in the Atlas provides an approximate
yardstick for measuring machine severity. This enables an activity, which currently
is subjective, to be quantitative and standard.
Part 3, Cotamination Level and ISO Cleanliness
The Contamination Level and ISO Cleanliness feature is one of four main features
of the Wear Particle Atlas CD-ROM. It provides a useful reference to estimate lubricant
cleanliness. The cleanliness reference in Atlas consists of 10 contamination levels
corresponding to the sequential ISO Cleanliness levels from ISO 13/10 up to ISO 24/21.
An example of ISO cleanliness and a corresponding contaminant level page is provided
Contamination Levels and Corresponding ISO Cleanliness
Contamination LevelISO Cleanliness
Level 1 ISO 13/10
Level 2 ISO 15/12
Level 3 ISO 16/13
Level 4 ISO 17/14
Level 5 ISO 18/15
Level 6 ISO 19/16
Level 7 ISO 20/17
Level 8 ISO 21/18
Level 9 ISO 22/10
Level 10 ISO 24/21
Each level contains 4 representative solid particle images grabbed from different
areas of the filtergram with varied magnifications. This component can be used to
correlate machine wear with lubricant dust contamination and to estimate the contamination
levels of some very dirty, very viscous, or water-contaminated oil samples. These
types of samples are usually unavailable or inconvenient for analysis by automatic
Part 4, Integration of Ferrogram and Filtergram Methods
The Integration of Ferrogram and Filtergram Methods feature is one off our main features
of the Wear Particle Atlas.The ferrogram method is excellent in identifying the
materials and the size and shape of solid particles, but is deficient in collecting
nonferrous particles. The filtergram method collects all solid particles larger than
the pore size of filter paper, but is restricted in identifying materials of solid
particles. The Wear Particle Atlas CD-ROM exclusively combines the two types of analysis.
It takes advantage of the best features of both the ferrogram and filtergram methods
thus compensating for their respective limitations to maximize the strengths of microscopic
wear particle analysis.
Figure (a) below shows an easy identifiable, nonferrous (lead/tin alloy) wear particle
image on a ferrogram. Their non magnetic deposition pattern makes the discrimination
of the lead/tin particles from the ferrous particles easy. These nonferrous particles
are difficult to identify on the filtergram. In this case, the color and brightness
of both ferrous and lead/tin alloy particles are very similar, see figure (b), due
to lack of the deposition features in orientation and locations as on a ferrogram,
(a) Lead/tin particle on ferrogram
(b) Lead/tin particle on filtergram
The filtergram method is, however, able to collect nonferrous metal particles with
high efficiency. This capability contributes to its high reliability to detect the
condition of nonferrous components. Figure (c) shows the massive rubbing copper wear
particles on a filtergram from a worm gearbox, revealing a high wear rate of the
copper worm gear. But the ferrogram, made of same volume of sample, shows a very
low copper particle concentration, as shown in figure (d). It is estimated that the
collecting efficiency of the ferrogram method for small copper particles is likely
to be less than 10% in this case.
(c) Copper particles on filtergram
(d) Copper particles on ferrogram
Thank you for visiting the "Integration of Ferrogram and Filtergram Methods" feature
of the Wear Particle Atlas CD-ROM.