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Research and Development Projects at Nynas René Abrahams Technical Manager Lubricants Tribology Days, 7-8 October 2015
Research and Development Projects at Nynas
René AbrahamsTechnical Manager LubricantsTribology Days, 7-8 October 2015
Outline
Nynas lubricant team and grease development labProjects at Nynas
Influence of blended oils in grease properties
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Grease development at Nynas
In 2011, Nynas invested in a grease development labIncrease our knowlegde about grease and grease productionBetter understanding of the behaviour of Naphthenic oils in greasesPractical assistance in solving customer problems, supply issuesReduce approval times of new productsDevelopment work and joint projects with customersPresent technical papers at conferencesPreparation of relevant material for our marketing departmentTransfer knowledge to sales department
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Grease laboratory
Pilot plantPenetrometerDropping pointPDSCFTIRFlow pressureRheometerDSCOil separation3 roll mill, etc
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Influence of blended oils in grease properties
Objective
In this study mineral oils from different crude oil sources and refined by different processes were used to produce lithium greases of similar grade and formulation.
The performances of said greases under relatively low and high temperature conditions were analysed. Flow pressure tests and rheological measurements were run.
High temperature rheology measurements were run and tribology tests using a Mini Traction Machine were used to measure the lubricating properties of the oils in a mixed rolling/sliding regime, at those conditions
The objective is to understand how different base oils influence the low and high temperature performance of the greases.
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Chemical composition of base oils
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Viscosity IndexColor
StabilityViscosity
Base oil manufacturing – Group II
Predominantly/exclusively conversion processes
Convert AromaticsRemove S, N and
Impurities
Remove or Convert
Wax
Pour PointCloud PointFilterability
(VI)
Remove Last Impurities
Thermal StabilityOxidation Stability
HydrocrackingSolvent, Catalytic or Iso-Dewaxing Hydrofinishing
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Base Oil Manufacturing – Naphthenic oils
Solvent extractionDistillation Hydro-finishing
No dewaxing step!
Fractionatecrude
Remove aromatics Remove S, N & impurities
Refined oils
Hydro-treatmentDistillation
Fractionatecrude
Wax-free naphthenic
crude
Convert aromatics, Remove S, N & impurities
Hydro-treated oils
Solvent extraction route
All hydrogenation route
Wax-free naphthenic
crude
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Characteristics of the oils
OilCrude oil type
Production method
IR Aromatic content (%)
Aniline point (°C)
Sulphur content (wt%)
Pour point (°C)
Viscosity at 40°C (cSt)
VI
A N-ic Hydrotreated 15 86 0.06 -30 109 -5
BN-ic
Severely hydrotreated
10 95 <0.01 -33 96 35
CP-ic
Hydrotreated/Hydrocracked
1 124 <0.01 -15 110 97
DN-ic
Solvent refined
7 95 0.9 -30 137 30
EP-ic/N-ic
Blend of oils similar to A/C
15 98 0.06 -33 140 46
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Grease Production : NLGI Grade 2
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Manufactured in an open kettle (pilot plant of 10kg capacity)Lithium hydroxide and 12-hydroxystereate thickener systemThe base oil mixture was used for cooking and coolingHomogenisation by a dispersion unitNo additives included in the formulation
Grease Characteristics
OilViscosity(cSt)
Penetration(mm -1 )
Thickenercontent (%)
100,000 str penetration (mm -1 )
Droppingpoint ( °C )
IR
Aromatic
content
of oil (%)
A109 287 7.18 313 (26) 199 15
B96 278 8.53 296 (18) 201 10
C110 284 10.16 261 (-23) 200 1
D137 278 8.50 295 (17) 199 7
E140 285 6.54 301 (16) 198 15
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Aromatic content of the base oil influences the oil – thickener interactions
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Low temperature analyses
Low temperature properties
Standard flow pressure test DIN 51805Conical nozzle filled with greasesTemperature progressively loweredFor each temperature the pressure applied to make the grease flow out of the nozzle is recorded (flow pressure)
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Flow pressure analyses
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0
200
400
600
800
1000
1200
1400
1600
1800
Sample A Sample B Sample C Sample D Sample E
hPa
Flow pressure (DIN 51805)
-35°C
-20°C
Rheology measurements
Anton Paar dynamic shear rheometerPlate on plate geometryDiameter of 3mm, load applied at a force of 20NTemperature sweep of the storage modulus
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Rheological measurements
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0
50000
100000
150000
200000
250000
300000
-20 -15 -10 -5 0 5 10 15 20 25
G´(Pa)
Temperature (°C)
Temperature sweep of Storage Modulus
Sample A
Sample B
Sample C
Sample D
Sample E
Low temperature influences
Flow pressure results and storage modulus results at lower temperatures follow the same trend.
Sample C shows the poorest low temperature performanceThis is a paraffinic base oil that has been de-waxed by isomerisation, which is a more severe process of de-waxing, however not all the waxes are converted to iso-paraffins and crystallisation takes place at lower temperature
The oils of samples A, B and D are refined in different way but are all based on wax free crudes
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High temperature analyses
Measurements
A Mini Traction Machine (MTM) was used to measure Stribeck curves and Electrical Contact resistance (ECR) between the disc and the ball.
AISI 52100 steel/steel contact between disc and ballLoad of 20NSliding Rolling Ratio (SRR) of 80%Results reported as average mean of 5 curvesAttachment to ensure grease stays in the contact
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Tribological measurements
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0
0,01
0,02
0,03
0,04
0,05
0,06
0,07
0,08
0,09
1 10 100 1000
Fric
tion
coef
.
Speed, mm/s
Stribeck curve of greases at 110°C
Sample A
Sample B
Sample C
Sample D
Sample E
Tribological measurements at 110°C
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0,0
20,0
40,0
60,0
80,0
100,0
120,0
1,0 10,0 100,0 1000,0
EC
R %
Speed, mm/s
% of full film in contact of grease samples
Sample A
Sample B
Sample C
Sample D
Sample E
Tribocell analyses on the rheometer
Stainless steel ball and platesNormal force set at 20 NTemperature set at 110°C
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Stribeck curves of base oils at 110°C
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0
0,01
0,02
0,03
0,04
0,05
0,06
0,07
0,08
0,09
0,1
0,11
0,12
0,13
0,14
0,15
0,16
0,17
0,18
0,19
0,2
0,21
0,22
µµµµ
100
101
102
103
mm/sSliding Speed v s
Stribeck Curve
Anton Paar GmbH
Sample A
µ Friction Factor
Sample B
µ Friction Factor
Sample C
µ Friction Factor
Sample D
µ Friction Factor
Sample E
µ Friction Factor
Tribological comments
Sample C displays the lowest friction coefficients at these conditionsThickener content and VI of the base oil
Sample E (a blend of the base oils from samples C and A) interestingly follows the trend of sample C at lower speeds and sample A at higher speedsIt cannot be concluded that the viscosity of the base oils is influencing the thickness of the oil film in the contact zone.
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Conclusions
Summary
In grease production:
The use of naphthenic oils in grease production result in higher yields (lower soap consumption), compared to if paraffinic Group II are used
Among naphthenic oils is those with lower refining degree (lower aniline point, higher aromatic content) the ones presenting higher yields (lower soap consumption
By blending naphthenic oil in a paraffinic Group II oil, it is possible to achieve the same yields as for pure naphthenic base oils
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Summary
In grease properties:
The greases based on the oils giving high yield (low thickener content) have:
Better flowability at low temperaturesLower storage modulus or less resistance to flow at all temperature study
By blending a naphthenic oil with a paraffinic Group II oil one obtains a grease that has a naphthenic behaviour at low temperatures and a paraffinic one (relatively low friction) at high temperatures
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More information?
www.nynas.com/Base-oils
www.linkedin.com/company/nynas-base-oils
Naphthenic Magazine
productfinder.nynas.com
Naphthenics base oils news letter
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Nynas Group Head OfficeP.O. Box 10700SE-121 29 StockholmSweden
Tel. +46-8-602 12 00Fax +46-8-91 34 27
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