Lubrication Training - Basics of Lubrication
Types of Lubrication
Hydrodynamic
Boundary
Mixed
Hydrodynamic Lubrication
Occurs when machine parts are completely
separated by a full and continuous film of lubricant
Contact 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 Lubrication
Under 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 essential
Solid additives are mixed into the grease
Mixed Lubrication
Although 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 boundary
Mixed lubrication is characterized by the
likelihood of intermittent surface contact
EP and anti-wear are essential properties in the
lubricant
How is a lubricant made?
Select a base fluid:
MINERAL OIL
or
SYNTHETIC FLUID?
Selecting a base fluid:
MINERAL OIL
Paraffinic or Naphthenic
Readily available
Comparatively low cost
Limited performance.
Selecting a base fluid:
SYNTHETIC FLUIDS
PAO, PAG, Ester
Synthetically manufactured
Comparatively high cost
Improved performance
 Longevity
 Temperature
 Viscosity Index
Selecting a base fluid:
OTHER SYNTHETIC FLUIDS
Silicones
Fluorinated
Ultra Performance
 Ultra Temperature
 Long Life
 Lube 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?.
400C & 1000C
mm2 per second
=centistokes (cSt)
High
Low
Viscosity
(Thin)
Viscosity
(Thick)
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
Product enhancements:
Extreme Pressure (EP) Additives
CHEMICAL
SOLUTIONS
 Chlorine
 Sulphur
 Phosphorous
SOLID
LUBRICANTS
 Graphite
 Molybdenum disulphide
(MoS2)
 PTFE (Teflon)
Product enhancements
OXIDATION INHIBITORS
Longer wet life
CORROSION INHIBITORS
Improves corrosion protection.
TACKY ADDITIVES
Improves adhesion
Thickener Systems – turn fluids into greases
Improved Performance
-Temperature
-Mechanical stability
General
Purpose
Soap
Thickeners
Lithium complex
Calcium complex
Aluminium complex
Lithium soap Calcium
soap Aluminium soap
Thickener Properties
Lithium
 Good multi-purpose, good mechanical stability,
limited other properties
Lithium Complex
 Excellent high temp & mechanical stability
capability
Calcium Complex
 Excellent load carrying and water resistance
Aluminium Complex
 Excellent temperature capability & water
resistance
Other Thickener Systems
Other grease thickeners:
Bentonite clay
Silica
PTFE.
How is the grease thickness checked ?
NLGI PENETRATION TEST
NATIONAL
LUBRICATING
GREASE
INSTITUE of America.
NLGI Numbers - WHAT DO THEY MEAN?
NLGI No 6
BLOCK GREASE
Old Technology
NLGI No 5
SEMI-SOLID ELASTIC-LIKE
GREASE
Very rarely used, but can be found
in marine or shipping applications
NLGI No 4
VERY TACKY GREASE
Rarely used now, but found
sometimes found in heavy open
gears or mining equipment
NLGI No 3
HEAVIER GREASE
Used mainly for hand applied or
caulking guns
NLGI No 2
85% OF MARKET
Generally used in grease guns
NLGI No 1
THINNER GREASE
Generally used in grease guns,
slightly more pump- able for short
pipe lines
NLGI No 0
TREACLE LIKE GREASE
Used in semi-auto and auto
systems with shorts pipelines
SEMI FLUID/
NLGI No 00
SEMI FLUID GREASE
FLUID GREASE
NLGI No
000
FLUID GREASE
Generally
applied by
Used in semi-auto and automatic
systems
Automatic
Lubricator
Used in some gearboxes and semi
& auto lube systems with longer
pipe lines
HOW IS GREASE THICKNESS MEASURED?
Premium EP 2
NLGI 6
NLGI 5
NLGI 4
NLGI 3
NLGI 2
NLGI 1
NLGI 0
NLGI 00
NLGI 000
Premium EP 1
Premium EP 000
Summary
Base fluid
Mineral or synthetic
Viscosity
EP additives
Chemical and/or solids
Corrosion inhibitors
Oxidation inhibitors
Thickeners for greases.
BASIC FUNCTION OF A PRECISION BEARING
TO SUPPORT A ROTATING SHAFT
Outer Race
Balls or
Rollers
Shaft
Inner Race
Lubricant
BASIC FUNCTION OF A PLAIN BEARING
TO SUPPORT A ROTATING SHAFT
Plain Bush
Lubricant
Shaft
BASIC FUNCTION OF A SLIDE
TO SUPPORT A SLIDING LOAD
ALL BEARINGS/SLIDES HAVE ONE SURFACE
MOVING AGAINST ANOTHER
FRICTIONAL HEAT
WHY LUBRICATE?
FRICTIONAL HEAT
FRICTIONAL WEAR
WHY LUBRICATE?
Introduction of a lubricant film
REDUCES FRICTIONAL HEAT & WEAR
BASIC FUNCTION OF A LUBRICANT.
Reasons for bearing failure
Other reasons
21%
Improper
mounting
27%
Improper
lubrication
43%
Material
fatigue
9%
Breakdown of “improper lubrication” section
Over
lubrication
60%
Lack of
lubrication
40%
Potential failures due to over lubrication
Standard grease gun can develop 3,000 psi
High pressure grease guns can develop >6,000 psi
Potentially resulting in excessive drag causing:
 Increased power demand
 Ball/roller skid
 Increased friction
 Excessive heat
 Excessive race wear
 Degradation of the lubricant.
Correct Application of a lubricant
LITTLE & OFTEN!
Precision Bearings:
Typically fill 1/3 to 1/2 of vacant
area in bearing
High speed bearings require
approx. 1/3 fill
Plain Bearings
Typically fill until clean grease
shows.
Thank You
Any Questions?