This document discusses lubricants, their functions, properties, types, additives, and testing. The key points are: 1. Lubricants reduce friction and wear between moving parts, protect from corrosion, and carry away heat. The main types are solid, semi-solid (grease), and liquid. 2. Important lubricant properties include viscosity, viscosity index, flash point, pour point, and demulsification number. Additives enhance properties like chemical stability, viscosity, contamination control, and lubricity. 3. Lubricants are tested using standards like ASTM to determine properties. Grease viscosity is indicated using NLGI grades while oil viscosity uses ISO viscosity grades. Tests measure viscosity,

1. Lubricants
Sanjeet Kumar Nayak
GET (Mechanical)

2. Safety tip…
• Grinding dust from abrasive wheels is made
up of extremely fine particles of the metal and
the wheel and can be very dangerous to your
health.
Avoid inhaling such abrasive particles as much
as possible.

3. Definition
• Lubrication is the process, or technique
employed to diminish friction between
surfaces in close proximity, and moving
relative to each other, by interposing a
substance between them.
• The substance interposed is called lubricant.

5. Functions of Lubricants
• Reduce Friction & Wear
• Cool Moving Parts
• Absorb shock
• Sealing Agent
• Cleans Parts
• Prevents Corrosion
• Prevents thermal Expansion of parts
• Reducing Engine Noise
• Minimizes Energy losses

6. Lubricant
Film

7. Lubricant film thickness
1/100th of a paper sheet
Withstanding pressure of 10 cars on a
finger nail

8. Types (According to physical state)
Lubricants
Solid Semi-solid Liquid
e.g. Graphite e.g. Grease e.g. petroleum oil

9. • It’s a measure of a fluid’s resistance to flow. Viscosity of the lubricating oil
determines its performance under operating conditions.
• Too viscosity oil is thin and cannot stop friction.
• Too high viscosity oil is thick and has poor flow properties.
Parameters of lubricants
1.Viscoity
Viscosity : application :
( at 400
C) (indication)
10 – 25 cSt low temp, (very) high speed
70 – 200 cSt standard applications
300 – 1000 cSt (very) heavy load, (very) low speed

10. VISCOSITY INDEX :
• The rate at which viscosity of a lubricant changes with
temperature is measured by a scale called Viscosity Index.
• It is the decrease in viscosity of oil per degree rise in temp
between 38 °C & 99°C.
• Higher Viscosity Index means less variation of viscosity with
temperature.
Factor affecting Viscosity :
• Temperature : Viscosity decreases with increases in temperature.
• Load : Viscosity increases with increases in load.
• Speed/shear : Viscosity decreases with increases in speed.

11. Determination of Viscosity Index

12. Determination of VI (contd.)
• First the viscosity of the oil under test is determined at 38 °C Let it be U
• Then viscosity of 100 VI reference oil be H
• Then viscosity of 0 VI reference oil be L
• The values of 100 VI & 0VI oils is obtained from ASTM D2270.

13. • Iodine number is the number of Grams equivalent of iodine absorbed by 100gm
of oil.
• Each oil has its specific Iodine Number.
• Iodine Number determines the extent of unsaturation present in the oil.
Low Iodine Number is desirable in oils.
2. Iodine number

14. • Aniline point of an oil is defined as the minimum temperature at which
equal volumes of aniline(C6H5NH2) and the oil are miscible to form a
single phase upon mixing .
• Aniline Point is a measure of aromatic content of the lubricating oil.
• Low Aniline Point oil have high aromatic content which attacks rubber
seals.
• Aniline Point is used as an indication of possible deterioration of rubber
sealing etc.
A good Lubricants should have higher Aniline point
3. Aniline point

15. • Demulsification number defined as the number of seconds required for an oil
to separate from water after it has been emulsified under specified
conditions.
• A good lubricating oil should form such an emulsion with water which breaks easily.
This property is called demulsification.
• Quicker the oil separates out from the emulsion formed, better is the lubricating oil.
A good lubricating oil should have lower demulsification number.
4.Demulsification number

16. • Flash Point is the min temp at which the lubricant’s vapors' ignite for a moment
when tiny flame is brought near.
• Fire Point is the Min temp at which the lubricant’s vapours burn constantly for 5
seconds when tiny flame is brought near.
• Fire point = flashpoint + 5°C to 400 °C
• If flash point < 37.8 °C= Flammable liquids
And if flash point >37.8 °C =Combustible liquids.
For ease of storage and transportation lubricants with higher
flash point are preferred.
5. Flash point & Fire point

17. • Drop Point is the Temperature at which grease passes from the semi-solid state to
the liquid state.
• It determines the upper temp limit for the applicability of grease.
• It is applicable for grease only.
Higher Drop point is preferred in grease
6. Drop point

18. 7.Neutralisation number
• Neutralization number can be either a total acid number (TAN) or total
base number (TBN)
• Total Acid Number is a measure of the amount of potassium hydroxide
required to neutralize the acid contained in a lubricant.
• TAN indicates age and Oxidation extent in the oil.
• Total Base Number is a measure of reserve alkalinity in the oil. It is
measured by mg of KOH per gram of oil.
• Alkali is added in the oil as a corrosion inhibitor.TBN indicates corrosion
resistivity of the oil.
Higher TBN or Lower TAN is preferred in an oil.

19. • Cloud Point is the temp at which the lubricant becomes cloudy or hazy when
cooled.
• Lubricating oils used in capillary feed systems should have low cloud points,
otherwise impurities will clog the capillary.
• Pour Point is the temp at which the lubricant just ceases to flow when cooled.
• Pour point of wax can be lowered by dewaxing , addition of suitable pour
point depressant, by removing the viscous constituent of the oil.
Lower Cloud Point and Pour point is preferred in a Lubricant.
8.Cloud point and Pour point

20. Desirable properties
• High Chemical stability
• High thermal stability
• High boiling point
• Low freezing point
• Non-radioactive
• Ease of availability
• Economic viability

21. Additives
• Additives are the substances added to a lubricant to enhance
existing properties, suppress undesirable properties or impart
new properties so as to increase the range of applicability.
• These are classified along functional capabilities as :
» For chemical stability
» For viscosity
» For contamination control
» For lubricity

22. Additives for chemical stability
Detergents Metallo-Organic
compounds of Sodium,
Calcium and Magnesium
Chemically react with
sludge to neutralize them
and keep them soluble
Anti-Oxidants Aromatic Amines,
sulfurized phenols
Decompose peroxides,
Terminates free-radical
reactions
Rust-inhibitors Metal phenolates Provide protective film
Neutralize corrosive acids

23. Additives for Viscosity
VI improvers Polymers and copolymers
of olefins
Polymers expand with
increasing temperatures
This counteract oil thinning
Pour point
depressants
Alkylated naphthalene Modify wax crystal
formation to reduce
interlocking

24. Additives for contamination control
Dispersants (anti-
coagulants)
Alkylsuccinimide Contaminants are bonded
by polar attraction to
dispersant molecules.
Prevented from
agglomerating
Kept in suspension due to
solubility of dispersant
Anti-foaming agents Organic copolymers Reduce Surface tension to
speed collapse of foam
Seal swell agents Aromatic hydro carbons Chemical reaction with
gasket to cause slight swell,
resulting in tight seal

25. Additives for Lubricity
Anti Wear Organic Phosphates Chemical reaction with
metal surface and forms a
film. Prevents metal-to-
metal contact
Friction modifiers Organic fatty acids and
amides.
Preferential adsorption of
surface active materials
Extreme pressure
agents
organic sulfur and chlorine
compounds
Chemical action to form a
surface film

26. Lubricant Nomenclature
FOR LUBRICATING OIL
• According to ISO 3448 standards lubricating oils are named
according to their Viscosity grades.
• The Viscosity grade is suffixed
FOR GREASE
• Greases are given NLGI number in accordance with ASTM D-
217 test.

27. NLGI Grades as per ASTM D-217 TEST

28. Lab Tests - for lubricants
ASTM D 445
ASTM D 2250
ASTM D 97
ASTM D 92
ASTM D 664
ASTM D 217
Kinematic viscosity
Viscosity index
Pour Point
Flash Point
Total Base Number (TBN)
NLGI numbers

29. Example
SERVOMESH-320
• Viscosity :320-350cst(At 40°C)
• Viscosity Index : 90
• Flash Point : 232 °C
• Pour point : -3°C
USES:- Gear boxes
SERVOSYSTEM46
• Viscosity : 43-48cst (At 40 °C)
• Viscosity Index : 98
• Flash Point :200°C
• Pour point : -15°C
• Demulsification no : 20mins
USES :-Pumps

30. Thanks