An overview of the ASTM development and revision to D7918 to incorporate particle counting of greases

1. 1© 2016 MRG Laboratories. All rights reserved.
Automatic Particle Sizing and
Counting in Greases-Update
MRG Labs
York, Pennsylvania, USA

2. 2© 2016 MRG Laboratories. All rights reserved.
New Method: Particle Counting in Integrated
Tester D7918-17
• 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

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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.

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Camera Set-up
• Thin Film extrusion
sample preparation
• Lens magnification to
achieve 10 micron
particle resolution
• Backlit with LED lighting

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Particle Counting Example

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Particle Counting
Sample Image Image with filter and particles
highlighted

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Analysis Method
• Individual recordings are masked with a manual threshold
setting
• Segments of video ~50+ frames in length are selected for
analysis, ignoring portions that are out of focus or where the
grease film does not completely cover the field of view
• Software identifies particles in the recording segment
• Particles are placed in bins by equivalent circular diameter
• ≥10 um
• ≥25 um
• ≥80 um
• Particle mass fraction (mg/g) in each bin is reported based on
the measured particle area (um2) with the best fit equation from
the calibration study.
• (Particle Area) = 4471.2 (Mass Fraction) + 608.97

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Example Recordings
50 mg/g10 mg/g
1.0 mg/g
sample
0.1 mg/g
sample

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10. 10© 2016 MRG Laboratories. All rights reserved.
Current status and next steps
• Revision to D7918 in 2017 to add particle count and
moisture ppm completed
• Shared with G0 (Grease) Subcommittee and work on
Hegman Gage method ILS to be coordinated
• Hegman rating system A/B/C may be applied to this
automated method
• Grease cleanliness kits available from MRG Labs to
conduct particle counting of new and inservice greases