Definition – arc welding equipment – electrode types – filler and flux materials - arc welding methods – metal arc PREPARED BY DANIELRAJ K LECT/ MECH, LAPC Metal Inert gas (MIG) - Tungsten inert gas (TIG) - Submerged arc - Electro slag welding – resistance welding – spot welding – butt welding – seam welding – Plasma arc welding – Thermit welding – Electron beam welding – Laser beam welding – friction welding – ultrasonic welding – Induction welding - working principle – applications – advantages and disadvantagES

1. Welding technology
Unit - II
PREPARED BY
DANIELRAJ K
LECT/ MECH, LAPC

2. CO Identify joining methods for fabrications, and fabricate
simple job using joining method.
ARC WELDING GAS WELDING

3. WELDING
● Welding is a process of joining similar metals by the application of heat ,
● Welding are used to make permanent joints.
● It is used in the manufacture of automobile bodies , aircraft frames, machine frames,
boiler and ship building industry

4. Types of welding
Plastic welding : the metal piece are heated to a plastic state. They are
pressed together to make the joint
These plastic welding also known as pressure welding
Fusion welding : the metal piece heated to molten state. Then allowed to solid
state. Pressure is not applied in this welding process

5. Classification of welding

6. Arc welding
Arc welding is a type of welding process using an electric arc to create heat to
melt and join metals.
A power supply creates an electric arc between a consumable or non-consumable
electrode and the base material

7. Arc welding equipment
● Welding Machine: The welding machine used can be A.C. or D.C. welding machine. ...
● Electrode Holders
● Cables or Lead
● Cable Connectors and Lugs
● Chipping Hammer
● Wire Brush,
● Protective Clothing:
● Screen or Face Shield:

8. Electrodes, filler, flux material
Consumable electrode : these type of electrode are used to produce arc and
also used as filler material
Filler : filler metal is a material used to join two piece of metal during welding
Flux materials : these material which are used to i] remove oxides
Ii] stabilise the arc
Non consumable electrode : it made of carbon , graphite, tungsten

9. Metal arc welding

10. Tungsten inert gas welding
Arc is maintained between non consumable electrode and workpiece in a
protective inert gas atmosphere.
Component used :
● Tungsten electrode
● Argon gas supply
● DC power supply

11. `
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12. Metal inert gas welding
Arc is maintained between consumable electrode and workpiece in a protective
inert gas atmosphere.
Component required:
● Bare electrode
● Work piece
● Argon gas cylinder

14. Submerged arc welding

15. Electroslag welding
Electroslag Welding is a welding process, in which the heat is generated by an
electric current passing between the consumable electrode (filler metal) and the
workpiece through a molten slag covering the weld surface.
welding the gap between the two work pieces is filled with a welding flux
The slag reaches a temperature of about 3500°F (1930°C). This temperature is sufficient
for melting the consumable electrode and workpiece edges. Metal droplets fall to the weld
pool and join the work pieces.
Upheel welding or vertical axis welding

16. Electro slag welding

17. Plasma arc welding [ PAW]
Plasma Arc Welding is the welding process utilizing heat generated by a constricted arc struck between a tungsten non-
consumable electrode and either the work piece
Plasma is a gaseous mixture of positive ions, electrons and neutral gas molecules
Higher quality and speed than the TIG

18. Resistance Welding is a welding process, in which work pieces are welded due to a combination of a pressure
applied to them and a localized heat generated by a high electric current flowing through the contact area of the
weld.
Heat produced by the current is sufficient for local melting of the workpiece at the contact point and formation of
small weld pool (”nugget”).
The molten metal is then solidifies under a pressure and joins the pieces. Time of the process and values of the
pressure and flowing current, required for formation of reliable joint, are determined by dimensions of the electrodes
and the work piece metal type.
AC electric current is supplied through copper electrodes connected to the secondary coil of a welding transformer.

19. The following metals may be welded by Resistance Welding:
■ Low carbon steels - the widest application of Resistance Welding
■ Aluminum alloys
■ Medium carbon steels, high carbon steels and Alloy steels (may be welded, but the weld is brittle)
The most popular methods of Resistance Welding are:
■ Spot Welding (RSW)
■ Flash Welding (FW)
■ Resistance Butt Welding (UW)
■ Seam Welding (RSEW)

21. Friction stir welding

23. ● Electron Beam Welding is a welding process utilizing a heat
generated by a beam of high energy electrons.
● The electrons strike the work piece and their kinetic energy
converts into thermal energy heating the metal so that the
edges of workpiece are fused and joined together forming a
weld after Solidification.
● The electrons are emitted by a cathode (electron gun). Due to
a high voltage (about 150 kV) applied between the cathode
and the anode the electrons are accelerated up to 30% - 60%
of the speed of light.
● Kinetic energy of the electrons becomes sufficient for melting
the targeted weld. Some of the electrons energy transforms
into X-ray irradiation.

24. Ultrasonic welding

25. Ultrasonic Welding is a Solid State Welding process, in which two work pieces are bonded as a result of a
pressure exerted to the welded parts combined with application of high frequency acoustic vibration
(ultrasonic).
Ultrasonic vibration causes friction between the parts, which results in a closer contact between the
two surfaces with simultaneous local heating of the contact area. Interatomic bonds, formed under these
conditions, provide strong joint.
Ultrasonic cycle takes about 1 sec. The frequency of acoustic vibrations is in the range 20 to 70 KHz.
Thickness of the welded parts is limited by the power of the ultrasonic generator.
Ultrasonic Welding is used mainly for bonding small work pieces in electronics, for manufacturing
communication devices, medical tools, watches, in automotive industry.

26. Soldering is a method of joining two metal work pieces by means of a
third metal (solder) at a relatively low temperature, which is above the
melting point of the solder but below the melting point of either of the
materials being joined.
Flow of the molten solder into the gap between the work pieces is driven
by the capillary force. The solder cools down and solidifies forming a joint.
The parent materials are not fused in the process.
Soldering is similar to Brazing. The difference is in the melting point of
the filler alloy: solders melt at temperatures below 840°F (450°C);
brazing filler materials melt at temperatures above this point.
The difference between soldering and welding processes is more
sufficient: in the welding processes edges of the work pieces are either
fused (with or without a filler metal) or pressed to each other without any
filler material; soldering joins two parts without melting them but through
a soft low melting point solder.
Soldering joints have relatively low tensile strength of about 10000 psi
(70 MPa).
Filler rod material lead or tin

27. Brazing is a method of joining two metal work pieces by means
of a filler material at a temperature above its melting point but
below the melting point of either of the materials being joined.
Flow of the molten filler material into the gap between the work
pieces is driven by the capillary force. The filler material cools
down and solidifies forming a strong metallurgical joint, which is
usually stronger than the parent (work piece) materials. The
parent materials are not fused in the process.
Brazing is similar to Soldering. The difference is in the melting
point of the filler alloy: brazing filler materials melt at
temperatures above 840°F (450°C); soldering filler materials
(solders) melt at temperatures below this point.
The difference between brazing and welding processes is more
sufficient: in the welding processes edges of the work pieces are
either fused (with or without a filler metal) or pressed to each
other without any filler material; brazing joins two parts without
melting them but through a fused filler metal.

29. Tee joint welding
This joint looks like almost an English alphabet “T” and that’s why it’s called the Tee joint. In this joint, an object is welded
with another one which makes 90 degrees of angle each side.
Corner joint welding
In this type, joined objects make a shape like a corner or an angle. It’s one of the most popular joints and people also call it
the “L” joint. Construction of a box or a box frame uses this joint type.
Butt joint welding
Having the parts lied down at the same plane, butt joint can be done by welding their edges with each other. This type of
welding joint is used to join the valve and fittings.

30. Lap joint welding
When you’re welding and joining two objects or metals with each other, if there’s a difference between the thickness of each
metal, you need to apply lap-joint type.
Edge joint welding
The joint is most likely a parallel joint and with this, metals are attached with each other parallelly at one side or one edge.

31. Welding inspection
Destructive test
Non destructive test ( NDT)
1. ULTRASONIC TEST
2. X RAY TEST
3. MAGNETIC PARTICLE TEST

32. Laser beam welding (LBM)