Lubrication Training - Basics of Lubrication

Types of LubricationHydrodynamicBoundaryMixed

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Hydrodynamic LubricationOccurs when machine parts are completely separated by a full and continuous film of lubricantContact between the parts does not occur. Full-fluid-film lubrication is hydrodynamic lubrication, the oil adheres to the moving part and is drawn into the area between the rotating surfaces, where it forms a pressure, or hydrodynamic, wedge. A less common form of full-fluid-lubrication is hydrostatic lubrication, where the oil is supplied to the bearing area under pressure to separate the sliding surfaces.

Hydrodynamic Lubrication

Boundary LubricationUnder certain conditions such as shock loading, heavy loads, high temperature, slow speed and critically low viscosity, the lubricant is no longer hydrodynamic Frequent contact between the surfaces, resulting in a significant rise in temperature and subsequent destruction of the contacting surfaces. Under these circumstances, the fluid film is no longer capable of adequately protecting the surfaces. EP capabilities in the lubricant are essentialSolid additives are mixed into the grease

Mixed LubricationAlthough not a true mode of lubrication in the sense of hydrodynamic or boundary, mixed lubrication occurs more frequently then is realized.Mixed lubrication is a transitional mode of lubrication between hydrodynamic and boundaryMixed lubrication is characterized by the likelihood of intermittent surface contactEP and anti-wear are essential properties in the lubricant

Select a base fluid:

MINERAL OIL or SYNTHETIC FLUID?How is a lubricant made?

Selecting a base fluid:

MINERAL OIL

Paraffinic or NaphthenicReadily availableComparatively low costLimited performance.

Selecting a base fluid:

SYNTHETIC FLUIDS

PAO, PAG, EsterSynthetically manufacturedComparatively high costImproved performance

LongevityTemperatureViscosity Index

Selecting a base fluid:

OTHER SYNTHETIC FLUIDS

SiliconesFluorinatedUltra Performance

Ultra TemperatureLong LifeLube for Life

Base fluid selected:

Mineral or Synthetic

NOW SELECT THE REQUIRED VISCOSITY.

Selecting the required viscosity:

Generally thinner fluids are used for:

Lighter loads

Faster speeds.

Selecting the required viscosity:

Generally thicker fluids are used for:

Heavier loads

Slower speeds

So how do we measure viscosity?.

Low Viscosity(Thin)HighViscosity(Thick)mm2 per second=centistokes (cSt)400C & 1000C

What are the units of viscosity?mm2s = centistokes (cSt) = ISO VG (at 400C)

32 cSt - typical low viscosity (thin)680 cSt - typical high viscosity (thick)

ISO VG 15-22-32-46-68-100-150-220-320-460-680-1000 etc

SOLID LUBRICANTSGraphiteMolybdenum disulphide (MoS2)PTFE (Teflon) CHEMICAL SOLUTIONSChlorineSulphurPhosphorousProduct enhancements:Extreme Pressure (EP) Additives

Product enhancementsOXIDATION INHIBITORS

Longer wet life

CORROSION INHIBITORS

Improves corrosion protection.

TACKY ADDITIVES

Improves adhesion

Lithium soap Calcium soap Aluminium soapLithium complex Calcium complexAluminium complexImproved Performance-Temperature-Mechanical stabilityGeneral Purpose

Soap ThickenersThickener Systems turn fluids into greases

Thickener PropertiesLithium

Good multi-purpose, good mechanical stability, limited other propertiesLithium Complex

Excellent high temp & mechanical stability capabilityCalcium Complex

Excellent load carrying and water resistanceAluminium Complex

Excellent temperature capability & water resistance

Other grease thickeners:Bentonite claySilicaPTFE.

Other Thickener Systems

NLGI PENETRATION TEST

NATIONALLUBRICATING GREASEINSTITUE of America.How is the grease thickness checked ?

SEMI FLUID/FLUID GREASENLGI Numbers - WHAT DO THEY MEAN?Generally applied by Automatic Lubricator

NLGI No 6BLOCK GREASE Old Technology NLGI No 5SEMI-SOLID ELASTIC-LIKE GREASE Very rarely used, but can be found in marine or shipping applications NLGI No 4VERY TACKY GREASERarely used now, but found sometimes found in heavy open gears or mining equipmentNLGI No 3HEAVIER GREASEUsed mainly for hand applied or caulking gunsNLGI No 285% OF MARKETGenerally used in grease gunsNLGI No 1THINNER GREASEGenerally used in grease guns, slightly more pump- able for short pipe linesNLGI No 0TREACLE LIKE GREASEUsed in semi-auto and auto systems with shorts pipelinesNLGI No 00SEMI FLUID GREASEUsed in semi-auto and automatic systemsNLGI No 000FLUID GREASEUsed in some gearboxes and semi & auto lube systems with longer pipe lines

NLGI 6NLGI 5NLGI 4NLGI 3NLGI 2NLGI 1NLGI 0NLGI 00NLGI 000HOW IS GREASE THICKNESS MEASURED?

Premium EP 1Premium EP 2Premium EP 000

SummaryBase fluidMineral or syntheticViscosityEP additivesChemical and/or solidsCorrosion inhibitorsOxidation inhibitorsThickeners for greases.

TO SUPPORT A ROTATING SHAFT

Outer RaceInner RaceBalls or RollersLubricant

BASIC FUNCTION OF A PRECISION BEARING

BASIC FUNCTION OF A PLAIN BEARINGTO SUPPORT A ROTATING SHAFT Plain BushLubricant

BASIC FUNCTION OF A SLIDE

TO SUPPORT A SLIDING LOAD

FRICTIONAL HEATALL BEARINGS/SLIDES HAVE ONE SURFACE MOVING AGAINST ANOTHER

WHY LUBRICATE?

WHY LUBRICATE?FRICTIONAL HEATFRICTIONAL WEAR

Introduction of a lubricant film

REDUCES FRICTIONAL HEAT & WEAR

BASIC FUNCTION OF A LUBRICANT.

Reasons for bearing failure

Breakdown of improper lubrication section

Standard grease gun can develop 3,000 psiHigh pressure grease guns can develop >6,000 psi

Potentially resulting in excessive drag causing:Increased power demandBall/roller skidIncreased frictionExcessive heatExcessive race wearDegradation of the lubricant. Potential failures due to over lubrication

Correct Application of a lubricantLITTLE & OFTEN!Precision Bearings:Typically fill 1/3 to 1/2 of vacant area in bearingHigh speed bearings require approx. 1/3 fill

Plain BearingsTypically fill until clean grease shows.

Thank You

Any Questions?

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