Machinery Lubrication India Jan Feb 14 10 | Page 23

MLI

LESSONS IN LUBRICATION
BENNETT FITCH NORIA CORPORATION

ANATOMY of
Wear DEBRIS
This article is the fourth part of a series
of “anatomy” lessons within Machinery
Lubrication. In this issue, the various
modes by which wear debris is created
will be examined along with the physical
characteristics of each type of wear
particle.

In

addition,

microscopic

analysis and similar instrumentation
will be used to provide an in-depth look

deterioration processes may appear as
insignificant specks of mass that mostly
act and look the same. However, on a
microscopic level, this wear debris has a
unique morphology (shape and size)
and surface topography (roughness,
texture and surface pattern) based on
the deterioration process or wear mode

from a submicron size to chunks of
metal as large as can be imagined. Wear
debris analysis generally focuses on the
small, destructive particles, many of
which are too small for the human eye
to see. These particles may be less than
1 micron to 200 microns in size. If you
have particles larger than 200 microns,

at these particles’ unique appearances

TABLE 1. WEAR PARTICLE ANALYSIS TECHNIQUES

and how they are formed.

INSTRUMENTATION

Mechanical

equipment

deteriorates

ANALYSIS METHOD

RESULTS

High heat vaporization of
Spectrometric analysis
metals

Parts per million (ppm) of elements

Particle counting

Laser light scatter
or pore blockage

Number and size
of particles

Direct image particle
counting

Shadow casting
from laser

Number and size
of particles

fatigue, rubbing, sliding, abrasion and

Ferrous density
analysis

Magnetic flux

Number and size
of particles

corrosion.

Analytical ferrography

Microscopic analysis

Shape, size, texture, color, orientation, etc.

over time. Depending on the type of
work and environmental conditions a
machine endures, internal mechanical
deterioration can occur in the form of
From

a

macroscopic

perspective,
wear

the
debris

produced
f r o m
these

by which it was produced. If clearly
understood, the morphology and
topography can offer clues that can be
used to prevent imminent machine
failure.
Wear debris can be defined as
particles produced from the
breakdown of surfaces within a
machine. These particles can range

you probably don’t need anyone to tell
you that there is a serious issue within
the machine.

Wear Debris Sampling
and Analysis
There are many wear debris analysis
techniques (see Table 1). Some of these
methods can even analyze wear debris
right from the oil sample. Analytical
ferrography requires wear debris to first
be isolated from the collected oil
sample. Pho ѽ