Presentation on theme: "SELECTING PERFORMANCE GREASE: Ten Crucial Questions Presented4-13-2006By Don Oldiges."— Presentation transcript:
SELECTING PERFORMANCE GREASE: Ten Crucial Questions Presented4-13-2006By Don Oldiges
Ten Crucial Questions 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.
Ten Crucial Questions Challenging Environments Environmentally Friendly Temperature Extremes Heavy Loads High Speeds Long Life Demands on Grease Performance
Ten Crucial Questions 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.
Ten Crucial Questions 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.
Ten Crucial Questions 2: Know the Types of Grease Aluminum, conventional Aluminum, complex Calcium, conventional Calcium, anhydrous Calcium, complex Lithium, conventional Lithium, complex Polyurea Organo-clay Silicone Grease is classified by penetration number and by type of soap or other thickener.
Ten Crucial Questions What is Grease? Antioxidant Antiwear Antirust Anticorrosion Extreme pressure VI Improver Tackifier Pour Point Depressant Solid Boundary Lubricants Dye Petroleum Oils Polyalpha Olefins (PAO) Polybutenes Esters Polyglycols Polyethers Silicones PFPE Grease Seller Fluid Lubricant Buyer Additive Seller Thickener Soap Lithium, Sodium, Barium, Calcium, Aluminum Non-Soap (inorganic) Clay, Graphite, Silica Carbon Black Non-Soap (organic) Polyurea, PTFE, Wax
Ten Crucial Questions Grease Compatibility Chart AluminumComplex Barium Calcium -Hydroxy CalciumComplex Clay Lithium -Hydroxy LithiumComplexPolyurea Aluminum ComplexCIICIIBBCB BariumICICIIIIII CalciumIICCICCBCI Calcium 12-HydroxyCCCCCCCCCI Calcium ComplexIIIBCIIICC ClayIICCICIIII LithiumBICCIICCCI Lithium 12-HydroxyBIBCIICCCI Lithium ComplexCICCCICCCI PolyureaBIIICIIIIC C = Usually compatible. B = Borderline compatibility (probably incompatible). I = Incompatible 12 All greases are not created equal, caution must be exercised when replacing or refilling a grease.
Ten Crucial Questions What Do Most People Use? 2004 Global Production per NLGI Survey Li Conventional 53% Li Complex 15% Ca Hydrated 10% Ca Anhydrous 1% Ca Sulfonate 1% Ca Complex 2% Al Conventional 0% Al Complex 5% Na Soap 2% Other Metal Soaps 1% Polyurea 5% Organo Clay 3% All Others 2%
Ten Crucial Questions 3: Know your Classifications SAE (Society of Automotive Engineers) API (American Petroleum Institute) AGMA (American Gear Manufacturers Association), ISO (International Standards Organization) NLGI (National Lubricating Grease Institute). Professional societies and organizations have established classifications for oil and grease. The most widely encountered are those of the following organizations:
Ten Crucial Questions 4: Know the Typical Performance Properties of Each type of Grease Max Usable Temp °F ThermalStability Lubricity WaterResistanceSalt WaterResistance Shear Stability OxidationStability RustProtection Pumpability Oil Separation Aluminum, conventional175 Aluminum, complex350 Calcium, conventional200 Calcium, anhydrous230 Calcium, complex350 Lithium, conventional275 Lithium, complex350 Polyurea350 Organo-clay350 Sodium350 Excellent Good Fair Poor
Ten Crucial Questions 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 Purpose EP Grease MIL-G-18458 Wire Rope Grease MIL-G-21164C Grease, Moly Disulfide MIL-G-25760 Synthetic Grease MIL-G-46886 Silicone Grease EXAMPLES Category - H1 Lubricants - General Incidental Contact Category - H2 Lubricants - General No Contact Category - H3 Soluble Oils
Ten Crucial Questions 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
Ten Crucial Questions Typical Grease Tests TestASTM Method Test Description Cone PenetrationD-217Depth a “cone” pushes into grease Dropping PointD-2265Temperature where grease “melts” Apparent ViscosityD-1092“Thickness” of grease 4 Ball WearD-2266Apply load until balls weld EvaporationD-972Weight loss from grease Copper CorrosionD-4048Chemical reactivity with metal Water WashoutD-1264Removal of grease by water Rust ResistanceD-1743Protection of iron & steels Oxidation StabilityD-942Storage stability
Ten Crucial Questions Common Test Equipment PenetrometerGrease Worker
Ten Crucial Questions What is Penetration? 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. ASTM D-217
Ten Crucial Questions Grease Shear Stability Motor-Matic Grease Worker Test 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. ASTM D-217-A
Ten Crucial Questions Four Ball EP Test 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 pre- selected and successively higher loads until the welding of the four balls occurs. ASTM D-2783
Ten Crucial Questions 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.