Machinery Lubrication India Jan Feb 14 10 | Page 26

Standards Relating to Wear Debris Analysis and Particle Characterization
ISO 16232 7/8: Road Vehicles – Cleanliness of Components of Fluid Circuits
Parts 7 and 8 of this ISO standard focus on the methods for determining the size distribution of particulate contaminants
and for characterizing their shape and physical profile, especially those from automotive components. The technique can be
applied to lubricants from most all machines that follow the same principle of incurring wear or ingression of particles into
the lubricated area of the components. The particles are analyzed microscopically using computer image analysis.
With proper method extraction managed, this ISO standard also specifies a method for particle sizing and counting by use
of microscopic analysis as well as an established system for expressing the results.
For more information regarding these standards, visit the International Organization for Standardization website at www.
iso.org.
ASTM D7684, D7670 and D7690: Microscopic Characterization of Particles from In-Service Lubricants (by
Analytical Ferrography)
These new ASTM standards specify methods for proper classification and reporting of results for in-service lubricants
containing particulate debris either from wear, ingression or elsewhere. Included in the standard guide is suggested
terminology for reporting, logical framework and possible root causes. The primary method for analysis within these
standards is through ferrography, either by use of linear or rotary glass slides, in addition to guides for filter debris analysis
and magnetic plug inspection, among other methods. For more information regarding these standards, visit the ASTM
website at www.astm.org.

Chunks or Irregular Particles
The adhesion theory offers a possible
explanation for why particles produce
irregular

shapes.

During

surface

adhesion, the asperities of two
contacting surfaces flatten each other,
creating a fracture on one of the
surfaces. The surface interaction

surfaces, they transform into unusual
shapes.

Non-Ferrous Corrosion Particles
Corrosion particles typically are
extremely small (submicron). Magnetic
collection techniques can be effective in
gathering these particles, which are too
small to view in individual detail.

Ferrous Oxide Particles

transfers fragment material, which
adheres to the opposing surface. This
can result in the formation of particles
that have unusual shapes and are a
mixture of elements. The shapes often
are difficult to define, as several wear
modes may be at work concurrently
within the system. As these wear
particles act as abrasive contaminants
between
continually
contacting

Oxide particles, which are either red or
black iron oxides, are produced from
chemical reactions between iron and
oxygen. Red oxides are an indication of
moisture in the system, while black
oxides indicate inadequate lubrication
and excessive heat generation in the

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system.

Other Particles
The particles described previously
comprise only those generated from
wear-induced causes, but a mechanical
system can contain an assortment of
other particles from environmental
contaminants like water, dust, etc., to
human-agency contaminants such as
machining byproducts. Even some
lubricant additives can be mistaken for