A full brief description of arc welding by Md.Wajahat Ali

1. Swami Vivekanand College Of
Engineering
Manufacturing Practices(MP)
Topic – Arc Welding.
Presentation to- Presentation by-
Md.Wajahat Ali
Mr. Satyendra Sharma

2. Welding

3. Welding is a process of joining similar
metals by the application of heat with or
without application of pressure and addition
of filler material. The result is a continuity of
homogenous material, of the composition
and characteristics of two parts which are
being joined together.
What is Welding ?

4. Types Of Welding :
Welding may be classified under two broad
headings:
2. Fusion
Welding
1. Plastic Welding

5. Plastic Welding / Pressurre Welding
The Piece of metal to be joined are
heated to a plastic state (melted state)
and forced together by external
pressure.
Example: Resistance Welding

6. Fusion Welding / Non-Pressure
Welding
The material at the joint is heated to a
molten state and allowed to solidify.
Example: Gas welding, Arc welding

7. Applications of Welding :
 Welding is used for making permanent
joints.
It is used in the manufacture of automobile
bodies, aircraft frames, railway wagons,
machine frames, tanks, furniture, boilers,
and ship
building.

8. Fabrication of Steel
furniture,gates,doors
etc.
Welding of tubes and
pipes, chains, LPG
cylinders and other
items.
Soldering for joining
electronic components
to printed circuit boards.

9. Dangers of Welding:
Most fatalities that occur while
welding fall into following categories:
:Falls
:Fire / Explosions
:Eye damage from flash burns
or Ultraviolet (UV) Radiation
:Flash burns to the welder.
:Inhalation of dangerous fumes.

10. Personal Protective Equipment:
Wear the appropriate
Personal
Protective Equipment
(PPE) for the job:
- Eye Protection
- Burn Protection
- Inhalation Protection

12. History of Arc Welding:
:The electric arc was
discovered by Sir Humphry
Davy in 1808
:N.G. Slavianoff and
C.L. Coffin developed metal
electrodes in the late 1800’s
:Around 1900, A.P. Strohmenger
stabilized the arc with coated
metal electrodes
:In 1919, C.J. Holslag
invented AC welding
Sir Humphry Davy

13. History of Arc Welding:
:By WWI, welding began
replacing rivets on ships
due to time savings
:By the end of the war,
Germans, Americans and
British were arc welding
ships and airplanes
:Other advances to
strengthen the welds led
to much larger usage by WWII

14. Defination:-
Arc Welding - A fusion process for joining
metals. Through the application of intense heat,
the metals at the joint intermix (often with a filler
material) to create a metallurgical bond as
strong as the original two metals.

15. -An electric current, in the form of either alternating
current or direct current from a welding power supply,
is used to form an electric between the electrode and
the metals to be joined.
-As the weld is laid, the flux coating of the electrode
disintegrates, giving off vapors that serve as a
shielding gas and providing a layer of slag, both of
which protect the weld area from atmospheric
contamination.

16. Because of the versatility of the process and the
simplicity of its equipment and operation, shielded metal
arc welding is one of the world's most popular welding
processes. It dominates other welding processes in the
maintenance and repair industry.
-The process is used primarily to weld iron and steels
(including stainless steel) but aluminum, nickel and
copper alloys can also be welded with this method

17. How an arc is formed?
-The arc is like a flame
of intense heat that is
generated as the electrical
current passes through a
highly resistant air gap.

18. Electric Power for Welding:
Current used for welding
may be:
1. AC
2. DC
For most purposes, DC is preferred.

19. AC:
Welding with AC is ideal for the following
types of welds-
-Fast fill
-Aluminium welding with high frequency
-Downhand heavy plate.

20. DC :
Welding with DC is ideal for the following
types :
-Single carbon brazing
-Cutting Tap
-Build up of heavy deposits
-Stainless steel welding
-Cast iron welding
-Rivet welding

21. OPERATION:
-To strike the electric arc, the electrode is brought into
contact with the workpiece in a short sweeping motion
and then pulled away slightly. This initiates the arc and
thus the melting of the workpiece and the consumable
electrode, and causes droplets of the electrode to be
passed from the electrode to the weld pool.
-As the electrode melts, the flux covering disintegrates,
giving off vapors that protect the weld area from oxygen
and other atmospheric gases.
-In addition, the flux provides molten slag which covers
the filler metal as it travels from the electrode to the
weld pool. Once part of the weld pool, the slag floats to
the surface and protects the weld from contamination as
it solidifies.

22. -Once hardened, it must be chipped away to
reveal the finished weld. As welding progresses
and the electrode melts, the welder must
periodically stop welding to remove the remaining
electrode stub and insert a new electrode into the
electrode holder. This activity, combined with
chipping away the slag, reduce the amount of
time that the welder can spend laying the weld,
making SMAW one of the least efficient welding
processes.

23. Equipments Req :
-A welding generator (D.C.) or Transformer (A.C.)
-Two cables- one for work and one for electrode
-Electrode holder
-Electrode
-Protective shield
-Gloves
-Wire brush
-Chipping hammer
-Goggles

24. ELECTRODES:
The choice of electrode for Arc Welding depends on a
number of factors, including the weld material, welding
position and the desired weld properties. The electrode is
coated in a metal mixture called flux.
Electrode coating has the following
basic functions:
- to improve the arc stability.
-to generate gases to act as a shield against the
surrounding
atmosphere in order to prevent weld contamination.
-to control the rate at which the electrode melts.
- to add alloying elements to the weld zone to enhance the
properties of the joint.

25. Arc Welding :
Advantages :
:-Most efficient way to join metals
:-Lowest-cost joining method
:-Affords lighter weight through
better utilization of materials
:-Joins all commercial metals
:-Provides design flexibility

26. Disadvantages:
:-Manually applied, therefore high labor cost.
:-Needs high energy which can cause danger.
:-Not convenient for disassembly.
:-Defects are hard to detect at joints.
:-Joint preparation cost is more.

27. Conclusions :
:Welding should only be carried out by experienced
welders directly supervised by a person who fully
understands the hazards involved
:Always properly maintain equipment
:Wear appropriate personal protective
equipment
:Perform a hazard identification and
risk assessment of any workplace prior
to commencement of any work.

28. Bibliography –
:Audel Welding Pocket Reference :
by Rex Miller.
:Welding Essentials :
by Frank Marlow.
:Google.com