The document discusses various electric arc welding processes. It focuses on metal arc welding and gas tungsten arc welding (GTAW), also known as tungsten inert gas (TIG) welding. Metal arc welding uses an electric arc between an electrode and base metal to weld pieces together. It can be done in various positions and with different materials but is slower than other processes. GTAW uses a tungsten electrode and inert shielding gas to weld reactive metals without contamination. It produces high quality welds but requires more complex equipment than other arc welding methods.

1. MANUFACTURING
TECHNOLOGY – I
CRAFTED BY:
RAMESH KUMAR A
Assistant Professor
Sona College of Technology
Salem
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2. ELECTRIC ARC WELDING PROCESSES
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3. ELECTRIC ARC WELDING
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 The process in which an
electric arc between an
electrode and a work piece is
utilized to weld base metals is
called an arc welding
 Most of these processes use
some shielding gas while
others employ coatings or
fluxes to prevent the weld
pool from the surrounding
atmosphere
 The various arc welding
processes are:
 Metal arc welding
 Carbon arc welding
 Metal inert gas welding
(MIG)
 Tungsten inert gas welding
(TIG)
 Plasma arc welding
 Submerged arc welding
 Electro-slag welding

4. METAL ARC WELDING
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5. METAL ARC WELDING…
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 Arc welding processes uses an
electrical power supply to create
and maintain an electric arc
between an electrode and the
base material to melt metals at
the welding point
 They can use either direct (DC)
or alternating (AC) current, and
consumable or non-consumable
electrodes
 The welding region is protected
by some type of inert or semi-
inert gas, known as a shielding
gas
 The manual metal arc process
occurs when two wires which
form part of an electrical circuit
are brought together and then
pulled slowly apart, an electric
spark is produced across their
ends
 This spark, or arc as it is called,
has a temperature of up to
3,600°C

6. METAL ARC WELDING…
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 As the arc is confined to a very
small area it can melt metal
almost instantly
 If one of these wires is
connected to the job and the
other to a wire rod or electrode,
as it is usually called, the heat
of the arc melts both the metal
of the job and the point of the
electrode
 The molten metal from the
electrode mixes with that from
the job and forms the weld.
 It is important to realize that
tiny globules of the molten
metal from the electrode are
forced through the arc (they do
not fall by gravity)
 If this were not so it would be
impossible to use this process for
overhead welding

7. PROS OF METAL ARC WELDING
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 Simplest of all the arc welding processes
 Equipment can be portable and the cost is fairly low
 A wide range of metals and their alloys can be welded
 Welding can be carried out in any position with highest weld quality
 The process can be very well employed for hard facing and metal
deposition to reclaim parts or to develop other characteristics like
wear resistance etc.,
 Joints (e.g. between nozzles and shell in a pressure vessel) which
because of their position are difficult to be welded by automatic
welding machines are easily accomplished by flux shielded metal arc
welding

8. CONS OF METAL ARC WELDING
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 Because of the limited length of each electrode and brittle flux
coating, it is difficult to automate the process
 In welding long joints (e.g., in pressure vessels), as one electrode
finishes, the weld is to be progressed with the next electrode
 Unless properly cared, a defect (like slag inclusion or insufficient
penetration) may occur at the place where welding is restarted with
the new electrode
 The process uses stick electrodes and thus it is slower as compared
to MIG welding

9. APPLICATIONS OF METAL ARC WELDING
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 Maintenance and repair industries
 Naval industry
 Pipelines
 Offshore platforms
 Construction of steel structures
 Weld carbon steel, low and high allow steel, stainless
steels, cast iron, aluminum, nickel and copper alloys

10. METAL ARC WELDING
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11. GAS TUNGSTEN ARC WELDING (GTAW)
TUNGSTEN INERT GAS WELDING (TIG)
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12. GTAW or TIG
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 Tungsten inert gas welding process also called as gas
tungsten arc welding is named so because it uses
electrode primarily made of tungsten and
inert gas
 For shielding the weld pool to prevent its contamination
from atmospheric gases especially when joining high
strength reactive metals and alloys such as stainless steel,
aluminium and magnesium alloys, wherever high quality
weld joints need to be developed for critical applications
like nuclear reactors, aircraft etc

13. GTAW or TIG
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 There are four basic components
 DC/AC power source to deliver the welding current as per needs,
 welding torch (air/water cooled) with tungsten electrode and gas
nozzle,
 inert shielding gas (He, Ar or their mixture) for protecting the
molten weld pool contamination from atmospheric gases
 controls for moving the welding torch as per mode of operation
(manual, semi-automatic and automatic)
 This process uses the heat generated by an electric arc between the
non-consumable tungsten electrode and work piece (mostly reactive
metals like stainless steel, Al, Mg etc.) for melting of faying surfaces
and inert gas is used for shielding the arc zone and weld pool from the
atmospheric gases.

14. GTAW or TIG
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