Mechanical Engineering is the Branch of Engineering.The mechanical engineering field requires an understanding of core areas including mechanics, dynamics, thermodynamics, materials science and structural analysis,Fluid Mechanics, Metrology and Instrumentation, Dynamics of Machinery- II, Manufacturing Processes II, Industrial Drafting and Machine Design, Engineering Graphics, Power Plant Engineering. Ekeeda offers Online Mechanical Engineering Courses for all the Subjects as per the Syllabus. Visit us: https://ekeeda.com/streamdetails/stream/mechanical-engineering

1. Chapter Name :- Welding Process
Topic Name :- Thermit Welding
• Thermite welding is a type of
fusion welding process
• It is also known as
Exothermic welding or
bonding
• This process is used to
welding a heavy and large
structures
• It requires no electrode and
power supply
Thermit
Welding

2. Chapter Name :- Welding Process
Topic Name :- Thermit Welding
• Principle
•In this process, welding is done by pouring superheated
liquid steel around parts to be joined
•A short molding process is to be done before welding

3. Chapter Name :- Welding Process
Topic Name :- Thermit Welding
▪ A mixture of fine aluminium powder and iron oxide
that produces a very high temperature on
combustion, used in welding and for incendiary
bombs
▪ Thermite reaction involving aluminium is also called
Goldschmidt alumina thermic reaction
▪ Usually this reaction is triggered by burning
magnesium ribbon in presence of Barium peroxide
What is Thermite / Thermit?

4. Chapter Name :- Welding Process
Topic Name :- Thermit Welding
❑ By weight, 75% of iron oxide and 25% of fine
aluminium powder (OR)
❑ Fine aluminium powder and iron oxide should
have a ratio of 1:3 (by weight)
❑ We can also use copper or chromium instead of
aluminium
Composition

5. Chapter Name :- Welding Process
Topic Name :- Thermit Welding
The ends of parts to be
joined are kept parallel with
a uniform gap between them
That gap is filled with wax
which becomes the pattern
Molding sand is rammed
around wax pattern
Pouring gate, heating gate
and risers are cut
Working

6. Chapter Name :- Welding Process
Topic Name :- Thermit Welding

7. Chapter Name :- Welding Process
Topic Name :- Thermit Welding
❖ Joints to be welded are preheated by a flame
(external source). Due to preheat wax melts and
goes out
❖ After melting of wax, weld joints are preheated due
to flame
❖ Then heating is stopped and heating gate is closed

8. Chapter Name :- Welding Process
Topic Name :- Thermit Welding
⮚ The mixture of aluminium and iron oxide is placed
in a crucible
⮚ Mixture is ignited using a match stick (or) small
magnesium wire. So combustion takes place in the
crucible
⮚ Barium Peroxide is added to the crucible. Barium
peroxide arises by the reversible reaction of O2
with barium oxide. The peroxide forms around
500°C and oxygen is released above 820°C
Preparation

9. Chapter Name :- Welding Process
Topic Name :- Thermit Welding
⮚ Due to combustion, thermite mixture becomes
superheated liquid within max. time of 30 seconds
⮚ That superheated liquid (pouring metal) have
temperature of 2500--3000°C (around 5000°F)
⮚ The reduction of ferric oxide by aluminium is
highly exothermic and therefore the iron formed
will be in the molten state

10. Chapter Name :- Welding Process
Topic Name :- Thermit Welding
⮚ Aluminium is chosen as metal since it has strong
affinity towards oxygen and its oxide, Al2O3 is a
highly exothermic compound
⮚ Reaction takes place:
Fe2O3 + 2Al --------> Al2O3 + 2Fe + heat

11. Chapter Name :- Welding Process
Topic Name :- Thermit Welding
❑ Crucible is placed directly above the joints to be
welded
❑ After preheating of joints, liquid thermite steel
from the crucible is poured into mold between the
gap to weld
❑ The molten metal solidifies and weld is completed
Joining Process

12. Chapter Name :- Welding Process
Topic Name :- Thermit Welding

13. Chapter Name :- Welding Process
Topic Name :- Thermit Welding

14. Chapter Name :- Welding Process
Topic Name :- Thermit Welding
ADVANTAGES
•Very large size structure
can be easily weld
•No power supply and
electrode needed
DISADVANTAGES •Skilled labour required
•Long process

15. Chapter Name :- Welding Process
Topic Name :- Thermit Welding