GREASES
TEST
ROTOR
BLADE
GEN.
TREND
OES
PQ Index
FTIR
Water K.F.
Bleeding Out
Penetration
method is compared to the elemental analysis by OES, it can be
determined whether the water in the sample is "hard" or sea
water, which contains minerals like sodium or potassium, or if it
is soft water like condensate or rain water. If sodium, potassium,
calcium and magnesium are found in the used grease but are not
in the fresh grease, the presence of "hard" water is the likely
reason. Comparing these two methods, Karl Fischer titration
and OES, can also indicate whether the water was already
present in the fresh grease as part of the production process.
Additional Tests
RULER
Besides the previously described methods, which should be
the minimum requirement for grease analysis, there are a few
other tests that can be performed. The table on the left lists most
of these additional tests. Keep in mind that a failure investigation
after damage has occurred often requires a more complex analysis, and not every test method is designed to be a routine analysis.
In summary, grease analysis has proven to be a useful tool to
evaluate grease and bearing condition. Different situations and
influencing factors for wear, contamination and grease condition have shown complex coherences between the grease analysis
results and their practical meaning. This leads to the conclusion
that observing and interpreting these factors with expert knowledge can enable proactive maintenance strategies to be applied
in a reasonable way for grease-lubricated components.
NZ
Sohxlet
Extraction
Dynamic Shear
Viscosity
Sulfated Ash
VKA Four-Ball
Test Rig
Oil Separation
Dropping Point
Copper
Corrosion
28
FAILURE
January - February 2013 | www.machinerylubrication.com
