SELECTING PERFORMANCE GREASE: Ten Crucial Questions

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Dwain Summers
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1 SELECTING PERFORMANCE GREASE: Ten Crucial Questions Presented By Don Oldiges

2 Principles of Selection Manufacturer recommendations Manufacturers usually provide a list of lubricants that meet the operating requirements for their equipment. (note that the equipment manufacturer's recommendation should not necessarily be considered the best selection. Lubricant producer recommendations When manufacturers recommend lubricants for their products in terms of specifications or required qualities rather than particular brand names, lubricant producers should be consulted to obtain advice on products that comply with the required specifications. User selection The user should follow the manufacturer's specification ensure that applicable criteria are met regardless of who makes the lubricant selection.

3 Demands on Grease Performance Challenging Environments Environmentally Friendly Temperature Extremes Heavy Loads High Speeds Long Life

4 Performance Objectives of Grease To remain in contact with moving surfaces and provide lubrication even under the stress of gravity, centrifugal action or pressure. To retain its properties under use conditions at all levels of shear and temperature. While performing the above, the grease must still be able to flow or be pumped where it is needed.

5 1: Know When to Use Grease Applications suitable for performance grease. Machinery that is idle for long periods. Moving parts that are Sealed for Life Surfaces that are exposed to extreme conditions. Extending the life of worn components. Functional Properties Sealant to minimize leakage Sealant to minimize contamination Rigidity holds it in place where its needed Holds finely ground solid lubricants like moly or teflon.

6 2: Know the Types of Grease Grease is classified by penetration number and by type of soap or other thickener. Aluminum, conventional Aluminum, complex Calcium, conventional Calcium, anhydrous Calcium, complex Lithium, conventional Lithium, complex Polyurea Organo-clay Silicone

Extreme pressure VI Improver Tackifier Pour Point Depressant Solid Boundary Lubricants Dye Soap Lithium, Sodium,

7 What is Grease? Grease Additive Buyer Thickener Seller Fluid Seller Lubricant Antioxidant Antiwear Antirust Anticorrosion Extreme pressure VI Improver Tackifier Pour Point Depressant Solid Boundary Lubricants Dye Soap Lithium, Sodium, Barium, Calcium, Aluminum Non-Soap (inorganic) Clay, Graphite, Silica Carbon Black Non-Soap (organic) Polyurea, PTFE, Wax Petroleum Oils Polyalpha Olefins (PAO) Polybutenes Esters Polyglycols Polyethers Silicones PFPE

8 Grease Compatibility Chart All greases are not created equal, caution must be exercised when replacing or refilling a grease. Polyurea Lithium Complex Lithium 12 -Hydroxy Lithium Clay Calcium Complex Calcium 12 -Hydroxy Calcium Barium Aluminum Complex Aluminum Complex C I I C I I B B C B Barium I C I C I I I I I I Calcium I I C C I C C B C I Calcium 12-Hydroxy C C C C C C C C C I Calcium Complex I I I B C I I I C C Clay I I C C I C I I I I Lithium B I C C I I C C C I Lithium 12-Hydroxy B I B C I I C C C I Lithium Complex C I C C C I C C C I Polyurea B I I I C I I I I C C = Usually compatible. B = Borderline compatibility (probably incompatible). I = Incompatible

9 What Do Most People Use? Li Complex 15% Li Conventional 53% 2004 Global Production per NLGI Survey

10 3: Know your Classifications Professional societies and organizations have established classifications for oil and grease. The most widely encountered are those of the following organizations: SAE (Society of Automotive Engineers) API (American Petroleum Institute) AGMA (American Gear Manufacturers Association), ISO (International Standards Organization) NLGI (National Lubricating Grease Institute).

11 NLGI grease classification NLGI Number ASTM Worked Penetration Consistency Semi-fluid (Ketchup) Semi-fluid (Applesauce) Very soft (Deli Mustard) Soft (Tomato Paste) Common Grease (Peanut Butter) Semi-hard (Solid Shortening) Hard (Frozen Yogurt) Very Hard (Hard Butter) Solid (Brick Cheddar Cheese)

12 4: Know the Typical Performance Properties of Each type of Grease Oil Separation Pumpability Rust Protection Oxidation Stability Shear Stability Salt Water Resistance Water Resistance Lubricity Thermal Stability Max Usable Temp F Aluminum, conventional 175 Aluminum, complex 350 Calcium, conventional 200 Calcium, anhydrous 230 Calcium, complex 350 Lithium, conventional 275 Lithium, complex 350 Polyurea 350 Organo-clay 350 Sodium 350 Excellent Good Fair Poor

MIL-G-7711 General EXAMPLES Purpose EP Grease Category MIL-G-18458 - H1 Lubricants Wire Rope - General Grease Incidental MIL-G-21164C

13 5: Know Any Special Requirements Special Performance Requirements Federal Specs and Standards Mil Specs and Standards Food Grade Specifications ISO Standards ASTM Specifications EXAMPLES MIL-G-3545 High Temperature Grease MIL-G-4343B Grease, Pneumatic System MIL-G-7711 General EXAMPLES Purpose EP Grease Category MIL-G H1 Lubricants Wire Rope - General Grease Incidental MIL-G-21164C Contact Grease, Category Moly Disulfide - H2 Lubricants MIL-G General No Synthetic Contact Grease Category MIL-G H3 Soluble Oils Silicone Grease

14 6: Know the Grease Characteristics Required for the Application Apparent Viscosity (non-newtonian) Bleeding, Migration, Oil Separation Consistency, Penetration, NLGI Numbers Corrosion, Rust and Water Resistance Dropping Point Evaporation Oxidation Stability Pumpability Shear Stability Temperature effects Pressure Effects

15 Typical Grease Tests Test ASTM Method Test Description Cone Penetration D-217 Depth a cone pushes into grease Dropping Point D-2265 Temperature where grease melts Apparent Viscosity D-1092 Thickness of grease 4 Ball Wear D-2266 Apply load until balls weld Evaporation D-972 Weight loss from grease Copper Corrosion D-4048 Chemical reactivity with metal Water Washout D-1264 Removal of grease by water Rust Resistance D-1743 Protection of iron & steels Oxidation Stability D-942 Storage stability

16 Common Test Equipment Penetrometer Grease Worker

17 What is Penetration? ASTM D-217 Penetration with respect to a lubricating grease, is the depth (in tenths of a millimeter) that a standard cone penetrates a sample of the grease under prescribed conditions of weight, time, and temperature. Penetration is a measure of consistency of a grease to determine its plasticity.

18 Grease Shear Stability Ten Crucial Questions Motor-Matic Grease Worker Test ASTM D-217-A Shear or mechanical stability of a grease is its ability to withstand repeated working with minimum change in its structure or stability. The shearing action in the test apparatus simulates the working of the grease in service. The consistency is measured after 60 strokes and repeated after 10,000 or more strokes.

Four Ball EP Test ASTM D-2783 The test is the determination of the load-carrying capacity of a lubricant in kilograms applied to a system of four steel balls in the form of a tetrahedron.

19 Four Ball EP Test ASTM D-2783 The test is the determination of the load-carrying capacity of a lubricant in kilograms applied to a system of four steel balls in the form of a tetrahedron. The results are used to evaluate the EP characteristic of the lubricant by a load scar curve and weld point. The procedure consists of a series of 10-second runs made at preselected and successively higher loads until the welding of the four balls occurs.

Simple Rotational Viscometer ("Brookfield type") This device measures fluid viscosity at fixed rotation speeds by driving a measurement tool ("spindle"),

Viscous drag of the fluid against the spindle causes the spring to deflect, and this deflection is correlated with torque.

20 Simple Rotational Viscometer ("Brookfield type") This device measures fluid viscosity at fixed rotation speeds by driving a measurement tool ("spindle"), immersed in the test fluid, through a calibrated torsion spring. Viscous drag of the fluid against the spindle causes the spring to deflect, and this deflection is correlated with torque. The calculated shear rate depends on the rotation speed, the tool geometry, and the size and shape of the sample container. Conversion factors are needed to calculate viscosity from the measured torque, and are typically pre-calibrated for specific tool and container geometries.

1,000 5,000 500 3,000 2,000 300 200 1,000 100 500 50 300 200 30 20

21 Viscosity Grade Comparisons Ten Crucial Questions Kinematic Viscosity 40 C 2,000 Saybolt Viscosity Universal 100 F 10,000 1,000 5, ,000 2, , ISO/ASTM Viscosity AGMA Grades SAE Crank Case Oils SAE Gear Oil

22 7: Know how the Grease is Applied Automatic lubricating systems Pressure Injectors Metering pump Hand operated grease applicator Cartridge Grease Gun Grease Filler Pump Brush

23 Example of a Large Automatic Lube Application System

24 8: Know the Packaging Required & Available Small Containers Cartridges Aerosols Pails Drums or Totes

25 9: Know the Marketing/Supply Channel Where do I go to get Good grease? Performance Grease SUPPLIER GREASE MAKER DISTRIBUTOR PRIVATE LABELER CO-OP/ BUYING GROUP

26 10: Know the Life Cycle Fate Renewable & Safe Distribution Warehouse Consumer Packaged Grease Raw Materials Performance Grease Disposal Environmentally Responsible