A N N U A L E D I T I O N
30 Reliable Plant
|
www
.
reliableplant.com Machinery Lubrication
|
www
.
machinerylubrication.com 2025 Annual
If you have been in the Maintenance and
Reliability space for any length of time,
you may have heard someone say, "We
need to drain or change the oil because of
the number of particles that can be seen."
While checking for contaminants is a must for any
great inspection program, it is important to know that the
particles doing the most damage to machine parts are far
too small to be seen with the naked eye.
Why Small Particles Matter More
Without a magnifying glass or microscope, the
human eye can only see particles down to about 40
microns in size. e particles that damage our lubricants
the most are in the 3-10 micron range, which is much
smaller than what can be seen on a typical visual inspec-
tion of the lubricant.
ese particles are more concerning than their larger
counterparts because they are close to the size of typical
film thicknesses, which can allow them to go through the
load zone, causing damage to machine parts.
• Hydrodynamic Lubrication (Sliding)
- Typical oil films are 5-20 microns.
• Elastohydrodynamic Lubrication (Rolling)
- Oil films can be less than 1 micron.
Breaking It Down
Another issue with small particles is that they are
harder to break down. To understand this concept better,
think of breaking a large stick down to use for kindling
in your fireplace.
When the stick is long, you can snap it over your knee
or in your hands, breaking the larger stick into smaller
The human eye
can only see
particles down
to about 40
microns in size.
The particles
that damage our
lubricants the
most are
in the 3-10
micron range.
Particle Counting:
Why Smaller Particles
Lead to Big Trouble
CONTAMINATION CONTROL
Travis Richardson | Noria Corporation
