Tribology is the science of interacting surfaces in relative motion. It studies friction, wear and lubrication. Tribology is important for reducing friction and wear in machines to improve efficiency and save energy. It also aims to increase friction where needed, like in brakes. Proper tribological design can provide significant economic benefits and improve performance of components like bearings, gears, seals and more. Understanding tribological concepts helps prevent failures from issues like abrasive wear, pitting, cracking and other surface damage.

1. TRIBOL0GY
AWARENESS
ON
PROFESSIONALELECTIVE-III
BY
Mr. L. RAMESH
ASSISTANT PROFESSOR

2. `

3. What is Tribology?
• Tribology is defined as the science of interacting surfaces in relative
motion. The word tribology comes from the Greek tribos, meaning
rubbing. In any machine there are lots of component parts that
operate by rubbing together. Some examples are bearings, gears,
cams and tyres, brakes, and piston rings. All of these components
have two surfaces which come into contact, support a load, and
move with respect to each other. Sometimes it is desireable to have
low friction, to save energy, or high friction, as in the case of brakes.
Usually we don't want the components to wear so they are
lubricated.

4. APPLICATIONS

16. COULOMB
3. Friction independent of velocity
4. Friction tied to roughness
EULER
5. Static vs. dynamic friction

17. ECONOMIC BENEFITS

18. ECONOMIC BENEFITS

19. ECONOMIC BENEFITS

20. ECONOMIC BENEFITS

21. ECONOMIC BENEFITS

22. TRIBOLOGY USES
• carbon graphite seal is
employed to avoid leakage
of steam from rotary joints
of paper industry. Failure of
this component occurs due
to adhesive wear. Adhesive
wear causes uneven surface
that leads to reduction in
mechanical contact area.
Carbon graphite seal.

23. • Cams are used to transmit
rotary motion in reciprocating
motion. These components
are subjected to jerks in
sliding distance, which leads
to form some pits on the cam
surface. Creation of pits on
cam surface increases noise
pollution and reduces
mechanical performance.
Pitting of cam surface.

24. •Examples of two journal bearing.
•Left hand side is photograph of
centrally grooved engine journal
bearing. It appears that bearing is
worn out due to foreign particles.
•Right hand side is a photograph of
an aluminum bearing subjected to
heavy load, which causes shaft
surface to run over bearing inner
surface. In these examples of
journal bearing, wear increases the
clearance between shaft and bearing
and leads to reduction in load
support capacity of the bearing.
Abrasive wear Rubbing wear
Wear scar due to edge loading

25. Multi-row Roller Bearing Cracking
of outer ring is shown in Fig. Here
cracking means deep cracks which
breaks outer ring in number of
pieces. Such failure occurs due to
faulty manufacturing and wrong
assembly of roller bearing.
Tribological relations help
estimating increase in contact
stresses due to misalignment of
shaft and improper mounting of
bearing surfaces. Hencean
approximation on reduction in
service life can be estimated Failure of large size roller bearing

26. • Gear A pit on the surface of
gear tooth is shown in Fig.
The pit generally occurs due
to excessive contact stress.
Understanding the effect of
contact stress helps in
developing an equation for
estimation of perspective
gear life.
Gear teeth removed fromgear.
Pits on gear teeth.