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January - February 2015
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www.machinerylubrication.com
on the Mohs scale), which is roughly 1.5
times harder than chrome steel. Quartz was
chosen for comparison because it is one of
the most abundant minerals in soil
(primarily sand). Silica-dioxide crystals are
commonly referred to as quartz and can be
found in most soils. Soils can vary from
region to region, with some more abrasive
than others. For example, the soil around
my house in Oklahoma is classifi ed as clay
loam. This is a common soil type that has a
blend of different levels of sand, clay, silt,
etc. While other minerals in dirt can be
abrasive, it is the silica that cuts the most.
In areas with high concentrations of sand
in the soil, it is important that machines
susceptible to dirt ingression are outfi tted
with devices to prevent these particles from
getting inside the equipment.
Hopefully, you now have a better under-
standing of just how much harder dirt is
than bearing and gear surfaces. Consid-
ering that steel has a Mohs value of only
4.5, the old adage "tougher than nails"
doesn't sound quite as impressive and
perhaps should be changed to "tougher
than dirt."
About the Author
Wes Cash is a senior technical consultant
with Noria Corporation. He holds a Machine
Lubrication Technician (MLT) Level II certifi ca-
tion and a Machine Lubricant Analyst (MLA)
Level III certifi cation through the International
Council for Machinery Lubrication (ICML).
Contact Wes at wcash@noria.com.
IN THE TRENCHES
Machines susceptible to dirt ingression
should be outfitted with devices to
prevent these particles from getting
inside the equipment.
86%
of lubrication professionals say
particle ingression has caused
problems for their plant's equip-
ment, based on a recent survey at
MachineryLubrication.com
