STLE 2014 Paul Bonner Croda - Perfad 3100 initial results

www.crodalubricants.com

New Organic Friction Modifiers for Industrial Gear Oils

Paul Bonner


Outline

• Industrial gear oil (IGO) applications and technologies

• Benefits of friction reduction in IGOs

• Tribological testing of new IGO friction modifier

• Demulsibility and elastomer testing

• Further testing planned


Where are Industrial Gear Oils Used?

Wind turbines

Mining Mills (paper, textile, sugar)

Steel production


Wind Turbines

• Wind turbine gearboxes experience very high

contact pressures (Average 2.5 GPa)

• This generates high temperatures which places a lot

of thermal stress on the lubricant

• Wind turbine failures can be

catastrophic and are usually

caused by failure of the lubricant


Industrial Gearboxes

• The factories and mills where IGOs found are often hot and

humid where contamination is also a big issue

• Large gearboxes such as

those found in mills also

generate high torque values

• General trend is to smaller

gearboxes, higher loads and

more demand on the lubricant

and additives as the IGO runs

hotter


Types of Gears • Different gears experience different lubrication regimes

• Most gears are a mixed sliding/rolling contact

• Hypoid gears and worm gears

have a higher proportion of sliding

in the contact and require more

EP and anti-wear additives

• Therefore formulation can be gear

specific

• Gear oils are available in a range

of viscosities from 32 to 1000 cSt

Hypoid

Worm


IGO Requirements

• Rejection of water – Water can damage internal components

• Lower friction - Improved efficiency of the gearbox

• Foam control – Foam inhibits film

formation

• Paint/Seal compatibility – Lubricant

must not degrade protective seals or

coatings


Base Oil Technologies

Ester Base Fluids

• Environmentally acceptable lubricants

• Good oxidative stability

• Very good VI

• Hydrolytic stability can be problematic

• Seal/Paint compatibility issues

PAO/Ester Formulations

• Good oxidative and hydrolytic stability

• Good wear protection

• Good VI

• Good water rejection

• Ester needed for additive solubility

Polyalkylene Glycol (PAG) Base Fluids

• Energy efficiency

• Very high VI

• Low traction coefficient

• Low deposits

• Readily mixes with water

Mineral Oil Base Fluids

• Low cost

• Medium VI

• Less oxidative/thermal stability

• Shorter oil drain intervals

• Higher chance of deposits


Friction Modifiers

• A reduction in friction is desirable as it reduces oil

sump temperatures (Even more important in smaller

gearboxes with less oil)

• This leads to less thinning of the lubricant and a thicker

oil film which helps to prevent wear

• Organic friction modifiers have traditionally

struggled to find applications in gear oils due to

their tendency to promote emulsification.

ASTM D1401 result for IGO + 1% GMO


“IGO – FM”

• IGO-FM is a new friction modifier for IGOs that has the

following advantages over conventional chemistries:

• Fully saturated - thermally and oxidatively stable

• Low impact on emulsification properties

• Sulphur, ash and phosphorus-free

• Strong reductions in friction at high temperatures and high loads

• IGO-FM is compliant with all major global inventories


Typical Physical Properties IGO-FM

Acid value (mgKOH/g) 1.4

Appearance Light yellow

Biodegradability (OECD 301B) % >60

Cloud point ºC -14

Density @ 20ºC (g/ml) 0.97

Flash point (COC) ºC 275

Iodine value (gl/100g) 1.7

Kinematic viscosity @ 40ºC (mm2/s) 624

Kinematic viscosity @ 100ºC (mm2/s) 28

Phosphorus % 0

Physical form Liquid

Pour point ºC -15

Renewability % 100

Saponification value (mgKOH/g) 152

Sulphur % 0

Viscosity index 55


Performance Testing

• Tribological Testing

• MTM

• Stribeck curves (Friction vs speed)

• Variable load test (Friction vs contact pressure)

• HFRR

• Demulsification • ASTM D1401


Testing formulations

• All testing done with commercially available additive

packages

• All initial screening tests: PAO + 10% ester + 1.65% commercially

available additive package to the viscosity quoted


MTM – Stribeck Curves

• The above profile was used to generate Stribeck

curves (friction vs. speed) for an ISO 68 industrial

gear oil

Parameter Value

Speed 0.01 - 2 m/s

Temperature 150ºC

Contact Pressure 1 GPa

Slide/Roll Ratio 50%

Specimens AISI 52100 steel


ISO 68 MTM Stribeck Curves (150 ̊C) 40-50% reduction in friction at low speeds using 1% IGO-FM

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.01 0.1 1 10

Co

eff

icie

nt

of

Fri

cti

on

Speed (m/s)

IGO

IGO + 1% GMO

IGO + 1% IGO-FM


MTM – Variable Load Test

• PAO/ester base with 1.65%

addpack

• In this test, the speed was fixed at

0.05 m/s and the temperature

held at 100ºC

• Using a ball-on-disc, max. contact

pressure was 1.7 GPa

Parameter Value

Speed 0.05 m/s

Temperature 100ºC

Contact Pressure 0.65 – 1.7 GPa




ISO 220 MTM Variable Load (100 ̊C) • 30-50% reduction in friction across a range of contact pressures

0

0.02

0.04

0.06

0.08

0.1

0.6 0.8 1 1.2 1.4 1.6

Co

eff

icie

nt

of

Fric

tio

n

Contact Pressure (GPa)

ISO 220 IGO

ISO 220 IGO+ 1% IGO-FM


ISO 320 MTM Variable Load (100 ̊C) • Strong performance also evident in higher viscosity fluids

0

0.02

0.04

0.06

0.08

0.1

0.6 0.8 1 1.2 1.4 1.6

Co

eff

icie

nt

of

Fric

tio

n


ISO 320 IGO

ISO 320 IGO +1% IGO-FM


MTM – Variable Load Test

• Using a barrel-on-disc

configuration much higher

contact pressures can be

achieved

Parameter Value

Speed 0.05 m/s

Temperature 100ºC

Contact Pressure 1.25 – 3.2 GPa




ISO 220 MTM Variable Load (100 ̊C) • Frictional benefits are maintained at higher loads when lubricating

films become thinner

0

0.02

0.04

0.06

0.08

0.1

1.25 1.65 2.05 2.45 2.85 3.25

Co

eff

icie

nt

of

Fric

tio

n


ISO 220 IGO

ISO 220 IGO+1% IGO-FM


ISO 320 MTM Variable Load (100 ̊C) • Frictional benefits are maintained at higher loads when lubricating

films become thinner

0

0.02

0.04

0.06

0.08

0.1

1.25 1.65 2.05 2.45 2.85 3.25

Co

eff

icie

nt

of

Fric

tio

n


ISO 320 IGO

ISO 320 IGO +1% IGO-FM


MTM Variable Load Test Summary

• Performance demonstrated in both ISO 220 and ISO

320 fluids

• Excellent performance at low loads / contact pressures

• Performance maintained at high loads

• Significant for heavily loaded gear systems such as wind

turbines, which can experience contact pressures around

2.5 GPa


HFRR Testing Profile

• The following test profile was used to investigate the

activity of IGO-FM in the HFRR

Parameter Value

Stroke Length 1000 µm

Frequency 20 Hz

Load 400 g (1 GPa)

Temperature 100ºC

Test Duration 1 hour


ISO 68 HFRR Friction Results (100 ̊C) Almost 50% reduction in friction with IGO-FM

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0.18

0 1000 2000 3000 4000

Co

eff

icie

nt

of

Fric

tio

n

Time (s)

IGO

IGO + 1% GMO

IGO + 1% IGO-FM


HFRR Wear Scar Results 40% reduction in wear achieved by addition of IGO-FM

0

50

100

150

200

250

300

IGO IGO + 1% GMO IGO + 1% IGO-FM

Wea

r Sc

ar

(µm

)


Demulsification (ASTM D1401)

• Contact with water can lead to corrosion and loss of

performance

• The demulsification rig tests how readily the oil will reject

water, or whether it will instead form a stable emulsion.

5 Minutes

Mixing

30 Minutes

Standing Oil

Emulsion

Water


ISO 320 Demulsification Test – 30 mins • IGO-FM creates a much less stable emulsion than GMO in two

different PAO/Ester based IGO formulations

Commercial addpack 1 Commercial addpack 2


Seal compatibility

• Initial elastomer volume change with 1% IGO-FM in

PAO + 10% ester was screened in-house

• Freudenberg FB 73 11 008 static and dynamic seal

compatibility test required for Flender approval

Elastomer type

NBR HNBR ACM FKM

% Volume Change with 1% IGO-FM 7.9 2 -0.2 0.6


Ester base


ISO 220 MTM Variable load test (100 ̊C)

• 30% reduction in friction seen in ester (ISO 220)

0.00

0.02

0.04

0.06

0.08

0.10

0.6 0.8 1 1.2 1.4 1.6

Co

eff

icie

nt

of

Fric

tio

n


IGO

IGO + 1% IGO-FM


ISO 220 HFRR (100 ̊C) • Reduction in friction also seen in ester (ISO 220)

HFRR

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0.18

0 10 20 30 40 50 60 70

Co

effi

cien

t of

Fric

tio

n

Time (s)

IGO

IGO + 1% IGO-FM


HFRR Wear

217

198

0

50

100

150

200

Wea

r Sc

ar (

mm

2)

IGO

IGO + 1% IGO-FM

• HFRR wear slightly lower with 1% IGO-FM


IGO-FM Summary

Base

Chemistry

MTM

friction

HFRR

friction

HFRR

wear

Demulsibility Seal

compatibility

PAO/Ester Up to

50%

reduction

50%

reduction

40%

reduction

Excellent Excellent

Ester 30%

reduction

10 – 20%

reduction

Slightly

reduced

Not tested Not tested

• Further testing planned

• Test performance in mineral oil and PAG*

• FZG

• Energy efficiency*

• Full elastomer testing

Documents

STLE 2014 Paul Bonner Croda - Perfad 3100 initial results