Lubrication involves placing a substance between interacting surfaces to minimize friction. There are four main types of lubrication: solid, semi-solid, liquid, and gas/air. The lubrication regime depends on operating conditions and the degree of contact between surfaces, and includes hydrostatic, hydrodynamic, elastohydrodynamic, boundary, and mixed lubrication. Proper lubrication provides advantages like reducing friction and wear, protecting equipment, and improving efficiency, but can also increase costs and component wear if not applied correctly.

1. Submitted by
Chandra Mouli P
118CR0134
Tribology of Materials (CR-4102)
Assignment - 1
Course Mentor,
Prof. Debasish Sarkar
Department of Ceramic Engineering
Topic – Fundamentals of Lubrication

2. What is Lubrication ?
The presence of a substance in between the layers of a material to minimize friction between two
surfaces is referred to as Lubrication.
The term “Lubrication” is applied to two different situations, they are :
• Solid Lubrication
• Liquid Lubrication
• Gas/Air Lubrication
 Any substance employed as a powder or a thin, solid coating on a surface to prevent from harm
during a relative movement by reducing friction and wear is referred to as a Solid lubricant.
 A thick fluid layer between two moving surfaces inhibits solid–solid contact and can reduce friction
significantly is known as Liquid Lubrication.
 The friction between two moving surfaces can be reduced by putting a thick layer of air between
them is known as Gas/Air Lubrication.
Introduction

3. Types of Lubrication
There are 4 types of Lubrication, they are :
o Solid Lubrication
o Semi-Solid Lubrication
o Liquid Lubrication
o Gas/Air Lubrication
 Solid Lubricants include Silicon/Graphite powders and Molybdenum-disulfide
 Semi-Solid Lubricants include Grease and Wax
 Liquid Lubricants include Oils and Gel
 Gas/Air Lubricants include Air, Nitrogen and Helium

4. Types of Lubrication with examples
Semi-Solid Lubricant Solid Film Lubricant
Liquid Film Lubricant

5. Classification of Lubrication Regime

6. Types of Lubrication regimes :
o Hydrostatic Lubrication
o Hydrodynamic Lubrication
o Elastohydrodynamic Lubrication
o Boundary Lubrication
o Mixed Lubrication
Regime of Lubrication
The sort of Lubrication film formed under specified operating circumstances and depends on the
degree of contact between surfaces is referred as the Regime of Lubrication.

7. Fluid Lubrication without an external pumping agency
Schematic of Fluid Lubrication Regime

8. Hydrostatic Lubrication
• Hydrostatic Lubrication is defined as the full separation of
a kinematic pair's conjugated surfaces by a layer of fluid
that is pressured by an external piece of equipment.
• Hydrostatic Bearings have a great load-carrying capability
at low speeds, thus they're employed in applications like
huge telescopes and radar tracking systems that require
both high weights and low speeds
• When there is little or no relative motion between the surf
aces, Hydrostatic Lubrication is utilized
Hydrostatic Bearing
Hydrostatic thrust bearing with circular step pad

9. Hydrodynamic Lubrication
• Hydrodynamic Lubrication is described as a thick fluid layer
between two moving surfaces that prevents contact and
minimizes friction.
• Fluid-film or thick-film Lubrication is another name for
Hydrodynamic Lubrication
• Hydrodynamic Lubrication requires pressure build-up in the film
due to relative motion of the surfaces
• Hydrodynamic Lubrication doesn’t require any external pumping
agent
Hydrodynamic Bearing
Partial sleeve bearing having bath-type Lubrication

10. Elastohydrodynamic Lubrication
• Elastohydrodynamic Lubrication is a subset of hydrodynamic
Lubrication in which the contacting materials' elastic deformation
plays a key part in the lubrication process.
• Elastohydrodynamic Lubrication is most easily induced in severely
loaded contacts, such as point contacts of ball bearings and line
contacts of roller bearings and gear teeth, where stresses
operate across relatively tiny contact surfaces.
• Adhesive wear occurs during start–stop operations in
Elastohydrodynamic Lubrication, and corrosive wear of the
bearing surfaces can also occur as a result of lubricant
interaction.
Elastohydrodynamic Bearing
A Radial Ball Bearing

11. Boundary Lubrication
• Boundary Lubrication occurs when solid surfaces are sufficiently
close together that surface interaction between monomolecular
or multimolecular Lubricant films (liquids or gases) and solid
asperities dominates contact
• On bearing surfaces, Boundary Lubricants generate an easily
sheared coating, reducing adhesive and Chemical wear
• Boundary Lubrication can also occur in a starving contact
• Solid Lubricants are not subject to Boundary Lubrication
• On bearing surfaces, Boundary Lubricants generate an easily
sheared coating, reducing adhesive and chemical wear
Boundary Lubrication

12. Mixed Lubrication
• A grey region known as Mixed Lubrication exists between the
Hydrodynamic/Elastohydrodynamic and Boundary Lubrication
regimes, in which two Lubrication processes may be active
• Although there are more frequent solid contacts in Mixed
Lubrication, at least a portion of the bearing surface is
supported by a partial Hydrodynamic coating
• Mixed Lubrication is also known as Quasi-Hydrodynamic
Lubrication, Partial Fluid Lubrication, or Thin-Film Lubrication.
Mixed Lubrication

13. Advantages of Lubrication
o Keeps friction and wear at bay
o Protects the equipment
o Enhances the temperature control
o Improve the Life Span, Efficiency and reliability of equipment/machinery
o Reduces the downtime and cost associated with maintenance and repair

14. Disadvantages of Lubrication
o Increased in component wear
o Bearing damage
o Premature failure
o Higher energy usage
o Increased operating and maintenance costs

15. THANK YOU