TIG Welding , MIG welding, Carbon arc welding

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2. • Carbon arc welding
• Gas metal arc welding(GMAW)(MIG)
• Gas tungsten arc welding(GTAW)(TIG)
• Submerged arc welding
• Electro slag welding
• etc
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3. • Carbon Arc Welding (CAW) is a welding process, in
which heat is generated by an electric arc struck between
an carbon electrode and the work piece.
• The arc heats and melts the work pieces edges, forming
a joint.
• Electrode is non-consumable.
• Shields (neutral gas, flux) may be used for weld pool
protection depending on type of welded metal.
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4. CARBON ARC WELDING (CAW)
Carbon electrode
Weld Bead
Developed in 1884
1. Power source
2. Holder cable
3. Earth cable
4. Work
5. Carbon electrode &
6.Filler rod
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Used to weld: brass, bronze,
copper alloys

6. Advantages of Carbon Arc Welding:
• Low cost of equipment and welding operation;
• High level of operator skill is not required;
• The process is easily automated;
• Low distortion of work piece.
Disadvantages of Carbon Arc Welding:
• Unstable quality of the weld (porosity);
• Carbon of electrode contaminates weld material with
carbides.
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8. • It is also known as TIG welding.
• It uses tungsten as electrode (added with 1-2% thorium and
zircon. It improves electron emission and arc stability) that
is non-consumable (3400 o C )
• Electrode holder is used to fix it.
• Instead of flux An inert gas is supplied from a
cylinder passes through the nozzle to protect the welding zone.
• It surrounds the arc from the atmosphere and make a defect
free weld also it protects the tungsten electrode.
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9. Welding head:
• Light weight handle having tungsten holder.
• Gas flow – (also cooled the electrode)
• For high heat – water cooled guns.
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With shielding gas With out shielding
gas

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ER70S-6
is generally used
for mild steel
welding.
Rod dia 0.8 to 5mm
Speed 8mm/s to 50mm/s
Water outlet

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ER70S-6
is generally used
for mild steel
welding.
Rod dia 0.8 to 5mm
Speed 8mm/s to 50mm/s
Water outlet

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Rod dia 0.8 to 5mm
Speed 8mm/s to 50mm/s
ER70S-6 is
generally used
for mild steel
welding.

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15. AWS Chemical Composition Requirements
C = 0.06 – 0.15 Ni = 0.15 max
Mn = 1.40 – 1.85 Cr = 0.15 max
Si = 0.80 – 1.15 Mo = 0.15 max
P = 0.025 max V = 0.03 maxYoucaN
• ER indicates filler metal may be used as either an electrode or rod.
• 70 indicates in 1000 psi(pounds per square inch) increments the
minimum tensile strength of the weld metal produced by the
electrode when tested according to the specification. In this case, 70
indicates 70,000 psi.
• S indicates that the filler metal wire is solid.
• 6 indicates the chemical composition of the solid filler
metal wire. This wire has a Charpy V Notch impact property of -29 C.

16. • Filler material may or may not be used.
• Mostly DCSP (straight polarity ie. electrode to w/p electron
flow)is used. Because DCRP melts the tungsten.
• Used to weld: steel, aluminium, CI, stainless steel, nickel
based alloy, copper based alloy and low alloy steels.
• Used upto thickness 6.5mm.
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17. Applications
• Welding of sheet metal and thinner sections
• Precision welding in aircraft, chemical and instrumental
industries.
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18. • Advantages:
• No flux
• Speed welding
• Used in both ferrous and non-ferrous welding
• High quality welding
• No weld cleaning is necessary
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19. • Disadvantages:
• High cost
• Slow process
• Separate filler rod is required
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20. • 4. Gas Tungsten Arc Welding
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• Is a process where a continuously fed metal
electrode (Wire) contacts the base metal and
produces heat. The arc is shielded by an inert
gas

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39. • DC or Direct Current power supply
• Electrode or wire feed controller
• Wire drive roller assembly
• Shielding gas source (cylinder) & regulator
• Manually held Gun & ground clamps
• Wire reel
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40. • In MIG consumable electrode is used.
• Shielded gas also used (stable gases Ar, He,CO2). The gases
must be clean and free form moisture.
• Automatic wire feed mechanism.
• Wire Speed is depends on voltage.
• The GMAW process is performed using DCEP (Direct Current
Electrode Positive)
• Alternating current is never used for GMAW
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41. • Helium(He)
Better penetration, minimizing distortion, costly.
• Argon
Good electrical property(low ionization voltage ), cheaper than He,
superior oxide cleaning.
Due to its softer arc and less penetration it is best for thin metals.
• Carbon dioxide:
Cheaper one. But produces spatter and poor bead shape.
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42. Type, intensity and polarity of welding current
Electrode size
Electrode composition
Electrode extension
Shielding gas mix composition
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43. • Dip or short circuit- Electrode wire dips in weld pool, causing a
momentary shot circuit, burns the wire. This takes place at very
high speed 100 dips/s. drops of liquid metal get transferred by
gravity and surface tension.
• Globular- Drop by gravity, low current and voltage
• Spray- High current density, very small droplets and more
frequent.
• Pulsed arc welding- A duel power unit, rapid acceleration of
droplets due to peak and low current cycles.
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45. Operates at low voltages and welding current
Small fast-freezing weld puddle obtained
Useful in joining thin materials in any position, as
well as thick materials in vertical and overhead
positions
Metal transfer occurs when an electrical short
circuit is established
this cycle can repeat itself between 20 and as
much as 250 times per second.
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A - Electrode is short circuited to base
metal. No arc, and current is flowing
through electrode wire and base metal.
B - Resistance increases in electrode wire
causing it to heat, melt and “neck down”.
C - Electrode wire separates from weld
puddle, creating an arc. Small portion of
electrode wire
is deposited which forms a weld puddle.
D - Arc length and load voltage are at
maximum. Heat of arc is flattening the puddle
and increasing the diameter tip of electrode.
E - Wire feed speed overcomes heat of arc
and wire approaches base metal again.
F - Arc is off and the short circuit cycle
starts again.

47. Welding current and wire speed are increased above
maximum for short circuit
Droplets of metal have a greater diameter than the
wire being used
Spatter present
Welding is most effectively done in the flat position when
using globular transfer
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Globular transfer is often
a high voltage, high
amperage, high wire
feed speed transfer, and
is the result of using CO2
shielding gas (or 75%
AR-25% CO2) with
parameters higher than
the short-circuiting
range.

49. Occurs when the current and voltage settings are
increased higher than that used for Globular Transfer
Used on thick sections of base material, best suited for
flat position due to large weld puddle.
The spray is projected by electromagnetic forces
towards the weld pool
Spatter is minimal to none
Uses 5% to 10% CO2 mix with argon or oxygen.
>Forms very small droplets of metal
>Very good stability
>Very little spatter YoucaN

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Spray arc transfer “sprays” a
stream
of tiny molten droplets across the
arc, from the electrode wire to the
base metal.
Spray arc transfer uses relatively
high voltage, wire feed speed and
amperage values, compared to
short
circuit transfer.

51. GMAW-P was developed for two demanding reasons:
control of weld spatter and the elimination of incomplete
fusion defects common to globular and short-circuiting
transfer.
The welding current alternates between a peak
current and a lower background current.
This faster-freezing weld puddle is what allows the
pulsed-spray transfer to be used fort thinner metals,
Better control on out-of-position work.
Allows for larger wire sizes to be used on varied metal
thicknesses.
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In pulse spray transfer (GMAW-P)
the welding power source’s pulse
control pulses the welding output
with high peak currents
(amperage) which are set at levels
which will cause the transfer to go
into a spray. The background current
(amperage) is set at a level that will
maintain the arc, but is too low for
any metal transfer to occur.

53. • Most common application of MIG welding is automotive
repair and manufacturing.
• It can be even be used to reinforce the surface of a worn
out railroad track.
• Highly economic one so it is widely used in industries.
• Welding tool steels and dies.
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54. • No flux is used so no need to clean.
• Produce very high quality weld
• Weld zone is visible
• No possibility of cracks.
• There is no frequent change of electrode, so it is more
efficiency.
• Easily automated.
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55. • Weld surface must be clean and free from oil, grease, paint.
• On site welding is difficult one.
• Difficult to weld in small corners
• Equipment is costly
• Less portable one
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56. • Non consumable
electrode
• Tungsten electrode
• Electrode only generates
arc and does not melt.
• Water cooled torch
• Used to join dissimilar
metals.
• Join thin plates
• Filler rod is used
• Consumable electrode
• Bare welding wire made of
desire composition
• Electrode generates arc
and melts
• Water or air cooled torch
• Used to join similar metals
• Widely used for thick plate
joining
• No filler rod usedYoucaN

57. • 5. GMAW MIG Welding _ Wire Feed Welding
(go to 2 min 25sec)
• 6.MIG_Welding_Principles
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