Presentation at the ASTM June 2015 meeting in Ft. Lauderdale, FL, USA, to the Grease subcommittee on a new method for testing grease particulate using a direct imaging method on samples prepared by ASTM D7918.

1. 1© 2015 MRG Laboratories. All rights reserved.
Automatic Particle Sizing and
Counting in Greases
Rich Wurzbach
MRG Labs
York, Pennsylvania, USA

2. 2© 2015 MRG Laboratories. All rights reserved.
Background
• Particle counting is very important part of oil analysis
programs.
• Filtration and online contamination monitoring are used
to maintain lubricant cleanliness.
• No commercial-scale contamination tests for grease as
exists for oil, such as laser scattering particle counting.
• Abrasive contamination can be just as destructive in
grease applications.
• Monitoring can allow for intervention through improved
handling and manufacturing practices, grease flushing,
and changes to relubrication frequency, volume.

3. 3© 2015 MRG Laboratories. All rights reserved.
Current Methods
• Direct
– Analytical Ferrography – Labor intensive, difficult
preparation
– Federal Standard 791D, Method 3005.4, Dirt Content of
Grease, microscopic evaluation
– DIN 51813, Solid Matter Content of Lubricating Greases
• Indirect
– Elemental Spectroscopy – Elemental concentration don’t
tell the whole story
– P-Q testing with Hall Effect sensor – Only Ferrous debris
– Hegman Gage – Semi-quantitiative based on size
– ASTM D1404 "Deleterious Particles" - effect of particles
on scratching plates

4. 4© 2015 MRG Laboratories. All rights reserved.
Current Methods
• DIN 51813, Solid Matter
Content of Lubricating Greases
• Federal Standard 791D,
Method 3005.4
• Hegman Gage, ASTM D1210Source: “Deleterious Particles in
Lubricating Greases”, C. Coe, STLE Online

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Current Methods
• Analytical Ferrography
• ASTM D1404, Estimation of
Deleterious Particles in
Lubricating Grease

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Limitations of current methods
• Subjective interpretation of results
• Selection of solvent critical to some tests,
may be more difficult when evaluating
inservice lubricants to get complete
dissolution
• Time consuming and some expertise may
be required
• None would be considered production lab
ready

7. 7© 2015 MRG Laboratories. All rights reserved.
New Method: Particle Counting
• New method uses ASTM D7718 sampling standard
capture device for presentation of 1 gram
representative sample
• Samples can be obtained from:
– new grease in manufacturing process
– packaged new greases upon opening
– stored greases in opened packages
– grease guns and auto-lubers
– inservice samples in the machine
• Method sizes and counts particles reliably down to 10
micron in major axis, and provides aspect ratio and
other characterization information

8. 8© 2015 MRG Laboratories. All rights reserved.
Grease Sampling ToolsGrease Sampling Tools

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Grease Thief Analyzer for Die Extrusion

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Analysis Techniques
Sample is received. fdM+ is run Die extrusion is performed and substrate is made
Two strips are used to make
a dilution to run RDE/ICP.
One Strip is used
for FT-IR.
One Strip is Dissolved in Green
RULER solution to run RULER.

11. 11© 2015 MRG Laboratories. All rights reserved.
Die Extrusion prior to Particle Counting

12. 12© 2015 MRG Laboratories. All rights reserved.
Oil Particle Counter Principle Adapted
• WK29409 Standard Test Method for Automatic Particle
Counting and Particle Shape Classification of Oils Using a
Direct Imaging Integrated Tester (D02.96.7)
• Use of camera and particle identification and sizing
software originally used for flow-through oil particle
characterization
• Modification of platform and use of alternate lighting
methods

13. 13© 2015 MRG Laboratories. All rights reserved.
Camera Set-up
• Thin Film extrusion
sample preparation
• Lens magnification to
achieve 10 micron particle
resolution
• Backlit with synchronized
high-intensity LED lighting

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Modification of Grease Thief Analyzer

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Challenges
• Strobing backlight solved 2 problems
– Testing with frontlight set-ups were unsuccessful
due to the glare produced by the grease surface
– Samples were too dark and the film was too thick to
employ a traditional backlight – improvement
achieved with synchronized LED.
• Thin film preparation
– Provides a consistent gap thickness
– Allows for volumetric calculations

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Particle Mask

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Case Study
• Chiller Motor ODE Bearing
sample
• Relatively low wear levels
• Slightly elevated
concentrations of elements
the could be environmental
contamination
• Also showed signs of grease
product mixing
• Elemental Spectroscopy
doesn’t show the whole
picture
Fe Al Si Mg Zn FdM
3.1 2.4 9.5 34 645 99

18. 18© 2015 MRG Laboratories. All rights reserved.
Particle Counting
Sample Image Image with filter and particles
highlighted

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Particle Counting - Results
Particle Count: 327
Mean Area: 1564.2
Mean Major Axis: 45.0
Min Major Axis: 14.6
Max Major Axis: 184.2

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Particle Counting - Results

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Backlight arrangement

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Die Extrusion of Hegman samples
• Samples A, B,
E, and H could
be processed
without dilution
• Other samples
have excessive
attenuation of
light signal at
current
thickness and
content

23. 23© 2015 MRG Laboratories. All rights reserved.
Samples sent out in June 2014-Kaperick
GR-193-A PTFE containing
GR-193-B Lithium complex
GR-193-C Li-Cx w/MoS2 & polyethylene
GR-193-D Li-12 w/MoS2 & graphite
GR-193-E Lithium complex
GR-193-F Lithium w/white solids (ZnO, TiO2)
GR-193-G Polyurea
GR-193-H Calcium Sulfonate
Permis
sion L (mm) W (mm) D (mm) Volume (mm^3)
Lab A Afton Chemical Yes 165.1 25.4 0.100 419
Lab B ExxonMobil Yes 155.58 50.8 0.100 790
Lab C University of Akron Yes 127.5 33 0.100 161
Lab D Axel Christiernsson Yes 127.5 33 0.250 1052
Lab E SKF Yes 127 50.8 0.050 323
Lab F Chemtura Yes 165 11 0.100 182
Lab G Summit Yes 165.1 25.4 0.100 419

24. 24© 2015 MRG Laboratories. All rights reserved.
Proposed ratings-Kaperick/Afton
PTFE containing Lithium complex
Li-Cx w/MoS2 &
polyethylene
Li-12 w/MoS2 &
graphite
GR-193-A GR-193-B GR-193-C GR-193-D
Lab
A
Lab
B
Lab
C
Lab
D
Lab
E
Lab
F
Lab
G
Lab
A
Lab
B
Lab
C
Lab
D
Lab
E
Lab
F
Lab
G
Lab
A
Lab
B
Lab
C
Lab
D
Lab
E
Lab
F
Lab
G
Lab
A
Lab
B
Lab
C
Lab
D
Lab
E
Lab
F
Lab
G
<26 C C A C A C A A A A A A B C C C C C B B A C A C
26-80 B C A B A C A A A B A A B C A B C C A B A A B C
>80 A B A A C A A A A A A B A B C A A A A C
D1404 3 3 1 3 1 1 1 1 1 1 1 3 3 2 1 2
24
Lithium complex
Lithium w/white
solids (ZnO, TiO2) Polyurea Calcium Sulfonate
GR-193-E GR-193-F GR-193-G GR-193-H
Lab
A
Lab
B
Lab
C
Lab
D
Lab
E
Lab
F
Lab
G
Lab
A
Lab
B
Lab
C
Lab
D
Lab
E
Lab
F
Lab
G
Lab
A
Lab
B
Lab
C
Lab
D
Lab
E
Lab
F
Lab
G
Lab
A
Lab
B
Lab
C
Lab
D
Lab
E
Lab
F
Lab
G
<26 A A A C A A B B A C A C A C A C C C A C C C C C
26-80 A A A A A A A B A A A A B A A B C C B A B B C C
>80 A A A A A A A A A A A A A A A A A A A A
D1404 1 1 1 2 1 1 1 2 2 3 1 2 3 2 1 3
L (mm) W (mm) D (mm) Volume (mm^3)
Lab A Afton Chemical 165.1 25.4 0.100 419
Lab B ExxonMobil 155.58 50.8 0.100 790
Lab C University of Akron ` 127.5 33 0.100 161
Lab D Axel Christiernsson 127.5 33 0.250 1052
Lab E SKF 127 50.8 0.050 323
Lab F Chemtura 165 11 0.100 182
Lab G Summit 165.1 25.4 0.100 419

25. 25© 2015 MRG Laboratories. All rights reserved.
Sample A

26. 26© 2015 MRG Laboratories. All rights reserved.
Sample A Thresholding

27. 27© 2015 MRG Laboratories. All rights reserved.
Particle Sizing – Grease A
PTFE containing Lithium complex
Li-Cx w/MoS2 &
polyethylene
Li-12 w/MoS2 &
graphite
GR-193-A GR-193-B GR-193-C GR-193-D
Lab
A
Lab
B
Lab
C
Lab
D
Lab
E
Lab
F
Lab
G
Lab
A
Lab
B
Lab
C
Lab
D
Lab
E
Lab
F
Lab
G
Lab
A
Lab
B
Lab
C
Lab
D
Lab
E
Lab
F
Lab
G
Lab
A
Lab
B
Lab
C
Lab
D
Lab
E
Lab
F
Lab
G
<26 C C A C A C A A A A A A B C C C C C B B A C A C
26-80 B C A B A C A A A B A A B C A B C C A B A A B C
>80 A B A A C A A A A A A B A B C A A A A C
D1404 3 3 1 3 1 1 1 1 1 1 1 3 3 2 1 2
Table: Grease A
Size (microns) Sieve # Vol% Population% Population
--------------------------------------------------------------------------------------------------------------------------------
----------
0 - 10 pan 0 0 0
10-25 Custom 2.4 31.681362 3126
25 - 75 Custom 41.3 63.190433 6235
75 - inf 200 USS 56.1 5.128205 506

28. 28© 2015 MRG Laboratories. All rights reserved.
Sample B

29. 29© 2015 MRG Laboratories. All rights reserved.
Sample B Thresholding

30. 30© 2015 MRG Laboratories. All rights reserved.
Particle Sizing – Grease B
PTFE containing Lithium complex
Li-Cx w/MoS2 &
polyethylene
Li-12 w/MoS2 &
graphite
GR-193-A GR-193-B GR-193-C GR-193-D
Lab
A
Lab
B
Lab
C
Lab
D
Lab
E
Lab
F
Lab
G
Lab
A
Lab
B
Lab
C
Lab
D
Lab
E
Lab
F
Lab
G
Lab
A
Lab
B
Lab
C
Lab
D
Lab
E
Lab
F
Lab
G
Lab
A
Lab
B
Lab
C
Lab
D
Lab
E
Lab
F
Lab
G
<26 C C A C A C A A A A A A B C C C C C B B A C A C
26-80 B C A B A C A A A B A A B C A B C C A B A A B C
>80 A B A A C A A A A A A B A B C A A A A C
D1404 3 3 1 3 1 1 1 1 1 1 1 3 3 2 1 2
Table: Grease B
Size (microns) Sieve # Vol% Population% Population
--------------------------------------------------------------------------------------------------------------------------------
----------
0 - 10 pan 0 0 0
10-25 Custom
0.12127
2 40.289855 1251
25 - 75 Custom
1.16758
6 45.120773 1401
75 - inf 200 USS
98.7111
4 14.589372 453

31. 31© 2015 MRG Laboratories. All rights reserved.
Sample E

32. 32© 2015 MRG Laboratories. All rights reserved.
Sample E Thresholding

33. 33© 2015 MRG Laboratories. All rights reserved.
Particle Sizing – Grease E
Lithium complex
Lithium w/white
solids (ZnO, TiO2) Polyurea Calcium Sulfonate
GR-193-E GR-193-F GR-193-G GR-193-H
Lab
A
Lab
B
Lab
C
Lab
D
Lab
E
Lab
F
Lab
G
Lab
A
Lab
B
Lab
C
Lab
D
Lab
E
Lab
F
Lab
G
Lab
A
Lab
B
Lab
C
Lab
D
Lab
E
Lab
F
Lab
G
Lab
A
Lab
B
Lab
C
Lab
D
Lab
E
Lab
F
Lab
G
<26 A A A C A A B B A C A C A C A C C C A C C C C C
26-80 A A A A A A A B A A A A B A A B C C B A B B C C
>80 A A A A A A A A A A A A A A A A A A A A
D1404 1 1 1 2 1 1 1 2 2 3 1 2 3 2 1 3
Table: Grease E
Size (microns) Sieve # Vol% Population% Population
-------------------------------------------------------------------------------------------------------------------------------
-----------
0 - 10 pan 0 0 0
10-25 Custom 0.05 33.3 356
25 - 75 Custom 0.69 39.1 418
75 - inf 200 USS 99.2 27.4 293

34. 34© 2015 MRG Laboratories. All rights reserved.
Sample H

35. 35© 2015 MRG Laboratories. All rights reserved.
Sample H Thresholding

36. 36© 2015 MRG Laboratories. All rights reserved.
Particle Sizing – Grease H
Table: Grease H
Size (microns) Sieve # Vol%
Population
% Population
------------------------------------------------------------------------------------------------------------------------------
------------
0 - 10 pan 0 0 0
10-25 Custom 1.9 56.9 5044
25 - 75 Custom 7.2 41.9 3711
75 - inf 200 USS 90.8 1.1 98
Lithium complex
Lithium w/white
solids (ZnO, TiO2) Polyurea Calcium Sulfonate
GR-193-E GR-193-F GR-193-G GR-193-H
Lab
A
Lab
B
Lab
C
Lab
D
Lab
E
Lab
F
Lab
G
Lab
A
Lab
B
Lab
C
Lab
D
Lab
E
Lab
F
Lab
G
Lab
A
Lab
B
Lab
C
Lab
D
Lab
E
Lab
F
Lab
G
Lab
A
Lab
B
Lab
C
Lab
D
Lab
E
Lab
F
Lab
G
<26 A A A C A A B B A C A C A C A C C C A C C C C C
26-80 A A A A A A A B A A A A B A A B C C B A B B C C
>80 A A A A A A A A A A A A A A A A A A A A
D1404 1 1 1 2 1 1 1 2 2 3 1 2 3 2 1 3

37. 37© 2015 MRG Laboratories. All rights reserved.
Sources of Error
• Spurious dirt on substrate
– Maintain cleanliness of substrates, as in Analytical
Ferrography
• Optical artifacts such as bubbles, grease thickness
variations
– Algorithm to eliminate non-particle features
• Highly attenuating matrix
– Only applicable presently to high-transmittance
samples
• Some greases with distributed solid lubricants
– Moly, graphite, ZnO, TiO2 greases not good
candidates with current method due to attenuation

38. 38© 2015 MRG Laboratories. All rights reserved.
Future Work-Particle Counting
1. Screening D7718 Grease Thieves for opacity and
dilution prior to D7918 Die Extrusion
2. Evaluation of clear Extrusion Die for thin grease stream
3. Integration of technology to take video during extrusion
for count averaging across a video instead of an image
4. Automation of the data collection process
5. Particle identification and characterization
– Differentiating severe wear modes from normal
rubbing wear
1. Establishing target limits and evaluation criteria for
different applications