OilDoc_2013___Paul_Bonner_20130218_145919

www.crodalubricants.com

Friction Modifiers and Lubricity Additives for

Industrial Lubricants

Paul Bonner, Croda, Cowick, England John Eastwood, Croda, Cowick, England

Louise O’Sullivan, Croda, Cowick, England


Contents

• Introduction

• Neat Metalworking Fluids

• Hydraulic Fluids

• Industrial Gear Oils

• Summary


Friction Modifiers and Lubricity Additives

• A lubricity additive (LA) is a generic description for an additive added to a lubricant formulation to perform one or more specific tasks, such as, reduced wear, prevent metal-metal welding, to lower torque or to control friction

• A friction modifier is used to control friction, which may mean reducing the coefficient of friction to very low levels or it may mean controlling friction between specific values

• Ordinarily a formulator needs to chose one or more additives that are designed to perform one or more of these tasks

• e.g. FMs to reduce friction, extreme pressure (EP) additives to prevent welding, ZDDP for anti-wear protection

• The new FMs presented today have the capability to provide extremely low

coefficient of friction whilst significantly reducing wear


New Friction Modifiers

• Organic (C, H, O)

• Metal Free

• Free from Phosphorus, Sulphur and Chlorine • Examples of polymeric and non-polymeric • Tailored to specific applications


Models of a conventional FM GMO vs polymeric HPLA

Green = non polar - oil soluble, Yellow = polar – attractive to metal surfaces

Conventional and Polymeric Friction Modifiers


NEAT METAL WORKING FLUIDS


• Reduce the torque required for form tapping to provide greater energy efficiency

• Reduce wear to increase tool life

• Multi-metal applications

Aim


Neat Metalworking Fluids

• Group I mineral oils used as the base fluid • Polymeric High Performance Lubricity Additive (HPLA)

added at 8% and 16% for demonstration purposes

• HPLA can be used at lower treat-rates but will be dependent upon the application (base oil, formulation, metals to be machined, metalworking operation e.g. drilling, broaching, deformation, etc)


Lubrication Tests

• Micro-Tapping (form tapping) Torque Test

• Reichert Wear Test

• 4-Ball Wear Test

• Mini-Traction Machine (coefficient of friction)


Form Tapping

• Form tapping measured using a Microtap instrument - Aluminium Al 6061 - Hard Steel 1018 • Tests Conducted:

• 8% and 16% polymeric HPLA added to base oil and compared to: - Gp I base oil alone - Gp I base oil + 10% conventional ester (TMP Trioleate) - Gp I base oil + 7.5% HPLA + 0.5% phosphate ester

• 10% polymeric HPLA in base oil compared to: - Gp I base oil + 10% high viscosity ester (commercial products)


Micro-tapping Machine

• Records torque required to tap pre-formed holes • The results are reported as the maximum torque required

6mm form tapping • HSS tap • torque limit 700 Ncm • speed = 600 – 800 rpm • tap depth = 0.5 inch / 13 mm


Form Tapping (6mm) – Aluminium 6061 5 – 7 % torque reduction with HPLA vs. conventional ester

-5 %

-7 %


Form Tapping (6mm) – Hard Steel (1018) 16 – 23 % torque reduction with HPLA vs. conventional ester

fail

-16 % - 23 %


Form Tapping (6mm) – Aluminium 6061 HPLA vs. commercial high viscosity esters: comparable performance

0

20

40

60

80

100

120

140

160

Base Oil (ISO 32 - 68) Base Oil + 10% Ester (ISO46)

Base Oil + 10% HPLA Base Oil + 10% Comp A Base Oil + 10% Comp B

Torq

ue N

cm -13 %


-10 %

fail fail

Paul Bonner – OilDoc Conference & Exhibition 2013

Form Tapping (6mm) – Hard Steel (1018) HPLA vs. commercial high viscosity esters: 10% improvement over A, B fails


Paul Bonner – OilDoc Conference & Exhibition 2013

4 Ball Wear Scar Low wear and synergy between HPLA and phosphate ester


Reichert Wear Low wear and synergy between HPLA and phosphate ester: 60% reduction over 10% conventional ester

-42%

-60%


Mini-Traction Machine (MTM)

• 36N Load, ¾ “ ball on 46 mm disk, 3 runs • Slide roll ratio fixed at 50% • Speed range of 0 – 2 m/s • Temperatures of 100 ̊C and 150 ̊C


MTM Coefficient of Friction at 100 ̊C Excellent friction reducing properties !


MTM Coefficient of Friction at 150 ̊C Outstanding friction reducing properties !!

• Typical temperature in contact zone


Summary for Neat MWFs

• HPLA outperforms conventional esters in the form tapping of Al 6061 (5 – 7% less torque)

• HPLA outperforms conventional esters in the form tapping of mild steel and 1018

hard steel (up to 23% less torque)

• HPLA outperforms high viscosity esters in form tapping of hard steel by 10% over commercial sample A, with commercial sample B failing the test

• Provides excellent wear protection and can act synergistically with phosphate

ester

• Forms stable films, especially at higher temperatures and can provide a very dramatic reduction in frictional characteristics of mineral oil based neat oils

• HPLAs are also extremely effective in ester base fluids


HYDRAULIC FLUIDS


• Reduce friction of the fully formulated oil to: • lower the operating temperature of the oil and reduce wear

that can result from a reduction in viscosity of the hydraulic fluid at operating temperature

• Provide greater wear protection to low viscosity oils • Increase energy efficiency through the use of lower viscosity

hydraulic fluids

Aim


Hydraulic Fluids

• Group II mineral oil used as base fluid

• Two commercial additive packages evaluated

• Gp II base oil + additive packs top treated with 1% polymeric HPLA

• Coefficient of friction tested using MTM machine • Demulsification tested in 1:1 water over 30 minutes using ASTM

D1401-02


Commercial Additive Pack 1 + HPLA MTM results 100 ̊C

0

0.02

0.04

0.06

0.08

0.1

0.12

0.01 0.1 1 10

Coef

ficie

nt o

f Fric

tion

speed m/s

Commercial Addpack 1 + 1 %HPLA

Commercial Addpack 1


Commercial Additive Pack 2 + HPLA MTM results 100 ̊C

0

0.02

0.04

0.06

0.08

0.1

0.12

0.01 0.1 1 10

COEF

Speed m/s

Commercial addpack 2 + 1 % HPLA

Commercial addpack 2


Demulsification test

• Hydraulic fluids are required to pass a demulsification test ASTM D1401-02 to meet specifications. This is due to the likelihood of some water being entrained during use

• If a hydraulic fluid becomes emulsified then cavitation is likely

which causes a decrease in efficiency and high wear • A 1:1 (40 ml) water : oil was mixed by paddle stirrer at 1500 rpm

for 5 minutes and then observed


No HPLA

1% HPLA


Summary for Hydraulic Fluids

• HPLA provides extremely low coefficient of friction to the hydraulic fluids formulated using Gp II base oil and two commercial additive packs

• However, HPLA causes the hydraulic fluid to emulsify water

• A re-design of the friction modifier is required to maintain the outstanding low friction profile whilst improving demulsification


INDUSTRIAL GEAR OILS (IGO)


Aim

• Reduce the coefficient of friction of the gear oil

• Increase the efficiency of the power transfer

• Reduce wear


Industrial Gear Oils

• Base fluid used was PAO/ester blend (ISO 320)

• A commercial additive package was used as a reference add pack

• The base oil plus add package was top treated with a polymeric

HPLA (at 1%) and two different non polymeric HPLAs (at 2%)

• Coefficient of friction determined using the Mini-traction machine • Demulsification tested in 1:1 water over 30 minutes using ASTM

D1401-02


• Due to the higher viscosity of the IGO formulation the MTM had to be run at higher loads and temperatures than used for the metalworking fluids and hydraulic fluids in order to obtain a Stribeck curve covering both mixed and boundary lubrication regimes

Coefficient of Friction by MTM

Parameter Standard Values Modified IGO Values

Load 36 N 75 N

Ball / disk size ¾ “ on 46 mm disk ½ “ on 32 mm disk

Temperature 100C 150C


IGO – MTM Results Polymeric HPLA

• Polymeric HPLA shows no improvement over the commercial addpack


IGO – MTM Results Non-Polymeric HPLA

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.1

0.11

0.12

0.01 0.1 1 10

COEF

Speed m/s

PAO/Ester ISO 320

Commercial Addpack in PAO/Ester

Commercial Addpack with 2 %nonpolymeric HPLA 1 in PAO/Ester

Commercial Addpack with 2 %nonpolymeric HPLA 2 in PAO/Ester

Commercial Addpack with 1%polymeric HPLA in PAO/Ester

• Two non-polymeric HPLAs were tested and gave a good reduction in friction compared to the commercial addpack alone


Demulsification of Non-Polymeric HPLA 1 and HPLA 2

• HPLA 2 does not cause the industrial gear oil formulation to emulsify water


Summary of IGO

• Polymeric HPLA showed no improvement in frictional performance compared to the commercial additive pack

• Both non-polymeric HPLA 1 and HPLA 2 showed a significant reduction in coefficient of friction over the commercial additive pack

• Non-polymeric HPLA 1 failed the demulsification test whilst HPLA 2 passed

• The structure of the friction modifier is critical to get both reduced friction and

excellent demulsification properties in a PAO/ester based formulation

• The performance of the friction modifier is likely to be dependent upon the base oil and the additives in a given formulation and further work to understanding their mutual interactions will be required, which may require new FMs tailored specifically for unique base oil / additive pack combinations


Conclusion

• It has been shown that both polymeric and non-polymeric HPLA are effective in reducing friction in neat MWF, hydraulic fluids and industrial gear oils

• Polymeric HPLA reduces torque in neat MWF by 7% in aluminium and 20% in

hard steel vs. conventional esters and 10% vs. commercially available high viscosity esters. Wear is also reduced and synergy seen with phosphate esters

• Polymeric HPLA reduces friction in a hydraulic fluid additive pack but does not have the required demulsification properties

• Non-polymeric HPLA was found to reduce friction in an industrial gear oil additive pack whilst not negatively affecting demulsibility properties of the formulated lubricant

• For each application the properties of the base oil and the specifications demanded for the application dictate different novel lubricity additive / friction modifier molecules


Acknowledgements • Louise O’Sullivan – Applications Scientist

• John Eastwood – Marketing Manager


Disclaimer

The information in this publication is believed to be accurate and is given in good faith but no representation or warranty as to its completeness or accuracy is made. Suggestions for uses or applications are only opinions. Users are responsible for determining the suitability of these products for their own particular purpose. No representation or warranty, express or implied, is made with respect to information or products including without limitation warranties of merchantability or fitness for a particular purpose or non-infringement of any third party patent or other intellectual property rights including without limit copyright, trademark and designs. Any trademarks identified herein are trademarks of the Croda group of companies.

© Copyright Croda Europe Ltd 2013. All Rights Reserved

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