SELECTING PERFORMANCE GREASE: Ten Crucial Questions

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SELECTING PERFORMANCE GREASE Ten Crucial
Questions

• Presented
• 4-13-2006
• By
• Don Oldiges

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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.

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Demands on Grease Performance
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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.

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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.

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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

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What is Grease?
Soap Lithium, Sodium, Barium, Calcium,
Aluminum Non-Soap (inorganic) Clay, Graphite,
Silica Carbon Black Non-Soap (organic) Polyurea,
PTFE, Wax

• 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

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Grease Compatibility Chart
All greases are not created equal, caution must
be exercised when replacing or refilling a grease.
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C Usually compatible. B Borderline
compatibility (probably incompatible). I
Incompatible
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What Do Most People Use?
2004 Global Production per NLGI Survey
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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).

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NLGI grease classification
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4 Know the Typical Performance Properties of
Each type of Grease
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5 Know Any Special Requirements

• Special Performance Requirements
• Federal Specs and Standards
• Mil Specs and Standards
• Food Grade Specifications
• ISO Standards
• ASTM Specifications

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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

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Typical Grease Tests
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Common Test Equipment
Penetrometer
Grease Worker
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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.

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Grease Shear StabilityMotor-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

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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

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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.

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Viscosity Grade Comparisons
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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

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Example of a Large Automatic Lube Application
System
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8 Know the Packaging Required Available
Cartridges
Small Containers
Aerosols
Pails
Drums or Totes
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9 Know the Marketing/Supply Channel
Where do I go to get Good grease?
CO-OP/ BUYING GROUP
PRIVATE LABELER
GREASE MAKER
DISTRIBUTOR
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10 Know the Life Cycle Fate
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QUESTIONS???
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Anhydrous Calcium Grease
Excess Ca Hydroxide
Hydroxyl from 12-HSA
Ca Stearate
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Bentonite Clay Grease
Quaternary Amine
Hydrocarbon
SiO2
Hydrocarbon
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Calcium Complex Grease
Ca Hydroxyl
Ca Carboxylate
Excess Ca Hydroxide
Ca Acetate
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Lithium Complex Grease
Ketostearate
Excess Li Hydroxide
Hydroxyl from 12-HSA
Lithium Doublet
Hydrocarbon
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Lithium 12-Hydroxy Grease
Excess Li Hydroxide
Ketostearate
Hydroxyl from 12-HSA
Lithium Doublet
Hydrocarbon
Hydrocarbon
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Aluminum Complex Grease
Aluminum Hydroxyl
Aluminum Triplet
Aluminum Stearate
Hydrocarbon
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Silicone Grease
Hydrocarbon
SiO2
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Fluorosilicone Grease
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Polyurea Grease
Amine
Hydrocarbon
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Fatty Acids for Grease
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Grease Reactions
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Trimer Reaction
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PAO 4
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PAO 40
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