Page 49 - Fall 2023 EDM Today

EDM Today Magazine EDM Today Magazine EDM Today Magazine

Another factor that is
considered in oil life is that
of the acid number (AN), a
term used to characterize the
acidic constituents that are
present in oil. Acids can
form as a byproduct of heat.
At CLC, an ASTM D664,
EDM Today Magazine EDM Today Magazine EDM Today Magazine
Method A standard test is
performed on batches of
new oil as part of quality
control. The target for AN
with new batches of oil is in
the range of 0.10mg KOG/
gram of sample. Testing can
detect both weak inorganic
acids, such as that caused
by the oil oxidation, and
also strong inorganic acids,
such as hydrochloric and
sulfuric acids.
EDM Today Magazine EDM Today Magazine EDM Today Magazine
The test is also performed
on used oil as a measure of
degradation. For lubricants,
AN is one of the important
tests that give us a snapshot
of its overall health. For
condition monitoring, it is
critical that a sample of the
CLC X-Ray Fluorescence Spectrometer
new, unused oil is tested as
When addressing the question of oil life, it is important
to consider how oil is impacted by use. One of the major
lubricant, the AN provides insight into the overall life/
factors impacting oil life is that of the concentration of well to provide a starting point. While EDM oil is not a
health of the fl uid. In severe cases of elevated AN, the
dissolved metals that increase with use. The industry
acidic byproducts from EDM oil degradation can cause
EDM Today Magazine EDM Today Magazine EDM Today Magazine
typically uses the term dissolved metals, but it is more
corrosion of both ferrous and non-ferrous materials.
technically accurate to describe the phenomenon as
In general, an increase in an oil’s acid number of 1.5
dispersed solids. During a typical EDM cut, particles
over its starting value is an indication that the oil has
are created as small as 1 nanometer (0.001 micron).
reached the end of its useful life.
With typical fi ltration range of 5 microns nominal, or even
super-fi ne 1 micron absolute fi ltration, the particulate
concentration of these sub-micron
particles continues to build with
use. With particle sizes so small, the
effect is essentially the same as if
they were dissolved.
The CLC laboratory employs an
EDM Today Magazine EDM Today Magazine EDM Today Magazine
energy dispersive X-ray fl uorescence
(EDXRF) spectrometer to determine
the particulate contamination of oil.
This equipment tells us not only the
amount of contamination, but also
what the specifi c elements are that
make up the contamination.
CLC uses this equipment not only
for testing used EDM oil, but also
as a quality control check on new
batches of oil. Per ASTM D7751, it
can also check on the appropriate CLC Lab Team, from L – R: Edgar Roque-Leon, Quality Control Chemist; Samantha Prosser,
levels of additives that are part of
EDM Today Magazine EDM Today Magazine EDM Today Magazine
the blend.
R&D Chemist; and Ryan Hamilton, Laboratory Manager
47
EDM Today, Fall 2023 Issue