Grease particle counting ASTM 2015

1© 2015 MRG Laboratories. All rights reserved.

Automatic Particle Sizing and Counting in Greases

Rich Wurzbach

MRG Labs

York, Pennsylvania, USA


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.


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


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


Current Methods

• Analytical Ferrography• ASTM D1404, Estimation of

Deleterious Particles in Lubricating Grease


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


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


Grease Sampling Grease Sampling ToolsTools


Grease Thief Analyzer for Die Extrusion


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.


Die Extrusion prior to Particle Counting


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


Camera Set-up

• Thin Film extrusion sample preparation

• Lens magnification to achieve 10 micron particle resolution

• Backlit with synchronized high-intensity LED lighting


Modification of Grease Thief Analyzer


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


Particle Mask


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


Particle Counting

Sample Image Image with filter and particleshighlighted


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


Particle Counting - Results


Backlight arrangement


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


Samples sent out in June 2014-Kaperick

GR-193-A PTFE containingGR-193-B Lithium complexGR-193-C Li-Cx w/MoS2 & polyethyleneGR-193-D Li-12 w/MoS2 & graphiteGR-193-E Lithium complexGR-193-F Lithium w/white solids (ZnO, TiO2)GR-193-G PolyureaGR-193-H Calcium Sulfonate

Permission L (mm) W (mm) D (mm) Volume (mm^3)

Lab A Afton Chemical Yes 165.1 25.4 0.100 419Lab B ExxonMobil Yes 155.58 50.8 0.100 790Lab C University of Akron Yes 127.5 33 0.100 161Lab D Axel Christiernsson Yes 127.5 33 0.250 1052Lab E SKF Yes 127 50.8 0.050 323Lab F Chemtura Yes 165 11 0.100 182Lab G Summit Yes 165.1 25.4 0.100 419


Proposed ratings-Kaperick/Afton

PTFE containing Lithium complexLi-Cx w/MoS2 & polyethylene

Li-12 w/MoS2 & graphite

GR-193-A GR-193-B GR-193-C GR-193-DLab 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 complexLithium w/white solids (ZnO, TiO2) Polyurea Calcium Sulfonate

GR-193-E GR-193-F GR-193-G GR-193-HLab 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 419Lab B ExxonMobil 155.58 50.8 0.100 790Lab C University of Akron ` 127.5 33 0.100 161Lab D Axel Christiernsson 127.5 33 0.250 1052Lab E SKF 127 50.8 0.050 323Lab F Chemtura 165 11 0.100 182Lab G Summit 165.1 25.4 0.100 419


Sample A


Sample A Thresholding


Particle Sizing – Grease 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




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


Sample B


Sample B Thresholding


Particle Sizing – Grease B




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




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 Custom0.12127

2 40.289855 1251

25 - 75 Custom1.16758

6 45.120773 1401

75 - inf 200 USS98.7111

4 14.589372 453


Sample E


Sample E Thresholding


Particle Sizing – Grease E



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




D1404 1 1 1 2 1 1 1 2 2 3 1 2 3 2 1 3

Table: Grease E


------------------------------------------------------------------------------------------------------------------------------------------

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


Sample H


Sample H Thresholding


Particle Sizing – Grease HTable: Grease H


------------------------------------------------------------------------------------------------------------------------------------------

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



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




D1404 1 1 1 2 1 1 1 2 2 3 1 2 3 2 1 3


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


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

6. Establishing target limits and evaluation criteria for different applications

Science

Grease particle counting ASTM 2015