This document discusses lubricants, including their need, classification, characteristics, types of lubrication, and applications. It defines lubricants as substances that reduce friction between surfaces in contact. Lubricants are classified as liquid, semi-solid, or solid based on their physical state. They function to reduce friction and wear, act as coolants, provide corrosion protection, and improve machine efficiency. Common types of lubrication include thick film lubrication which uses fluids to separate surfaces, and thin film or boundary lubrication which is used under heavy loads with high viscosity lubricants. Lubricants have wide applications in engines, transmissions, hydraulics, and other mechanical systems.

1. By
-Abhijit H Jadhav (Roll no 02)
-(Roll no 03)
-(Roll no 04)
*Lubricant

2.  Need of lubricant
 Introduction
 Classification of lubricants
 Characteristics of lubricant
 Types of lubrication
 Function of lubricant
 Application of lubricants
 Biblography
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3.  Resistance to the motion (Friction) is created
when there is relative motion between two
surfaces.
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 Lubricants are used as a material between
surfaces to reduce friction.

4.  A lubricant is a substance introduced to reduce friction
between surfaces in mutual contact, which ultimately
reduces the heat generated when the surfaces move.
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 The process of introducing
lubricant is called Lubrication.
Functions of lubricants :
 Reduces the frictional resistance.
Reduces wear & tear, surface
deformation
 Acts as a coolant
 Provides protection against
corrosion
 Improves the efficiency of the
machine

5. Lubricants are classified on the basis of their
physical state as follows:
Liquid Lubricants or Lubricating Oils
Semi-Solid Lubricants or greases
Solid Lubricants.
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6.  Lubricating oils reduce friction and
wear between two moving metallic surfaces by
providing a continuous fluid film in between the
surfaces.
 Examples:
 Animal and Vegetable oils
 Petroleum oils
 Mineral oils
 Blended oils
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7.  Grease is a semi solid lubricant obtained
bythickening liquid lubricating oil through the
addition of a metallic soap.
 The thickness isusually sodium or calcium or
lithium soap.
 Types of greases
 Soda-base grease
 Lime-base grease
 Lithium-soap grease
 Barium-soap grease
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8.  Lubricant are solid in state and these are used
where
 The operating temperature and load is too high
 Contaminations of lubricating oils or greases by
the entry of dust or grit particles are avoided.
 Combustible lubricants must be avoided.Graphite
and Molybdenum disulphide are the widely used
solid lubricants
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9.  It must have high boiling
point or low vapour pressure.
 Thermal stability and
oxidation resistance must be
high.
 It must also have adequate
viscosity for particular
operating conditions.
 The freezing point must be
low.
 It must also have non-
corrosive property.
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10.  It reduces the maintenance and
running cost of the machine.
 It reduces unsmooth relative
motion of the moving surfaces.
 It reduces the loss of energy in
the form of heat that is it acts as
a coolant.
 It reduces waste of energy, so
that efficiency of the machine is
increased.
 It minimizes corrosion.
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11. *
Types Of
Lubrications
Thick Film or
Fluid Film
or hydrodynamic
Lubrication
Thin Film or
Boundary
Lubrication

12.  This is also called
Hydrodynamic or fluid film
lubrication.
 The moving/ sliding
surfaces are separated from
each other by a bulk
lubricant film (at least
1000oA thick).
 This bulk lubricant film
prevents direct surface to
surface contact so that the
small peaks andvalleys do
not interlock
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13.  When the lubricant is not viscous enough to
generate a film of sufficient thicknessto separate
the surfaces under heavy loads, friction may yet
be reduced with the proper lubricant
 The coefficient of friction is 0.05 to 0.15
 Lubricants used for boundary lubrication should
have high viscosity index, resistance to heat and
oxidation, good oiliness.
 Examples are Organic oils, Vegetable oils, Graphite
and Mineral Oils etc.
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14.  Used in vehicle Engine as oil.
 Used as gear box fluid.
 Hydraulic fuel
 Air compressor fuel
 Bearing and circulating system oils
 Refrigerator compressor oils
 Steam and gas turbine oils
 Piston engine oil.
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15.  www.wikipedia.org
 http://www.vidyarthiplus.in/engineering-
chemistry1-lubricants
 www.britannica.com/technology/lubrication
 https://books.google.co.in/books
 www.machinerylubrication.com
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