Transcript MIG Welding

MIG Welding
MIG Welding
– Metal Inert Gas, also
referred to as GMAW.
 GMAW – Gas Metal arc welding
 MIG
MIG Welding
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A semi-automatic welding process using a DC
power source, a wire feeder, shielding inert
gas, and a consumable electrode.
Advantages of MIG
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Faster than arc
Smooth bead
Easy to start b/c can place nozzle on metal
without creating arc
No slag to chip off
Less damage to base metal b/c of fast travel
speed
Can join both ferrous and nonferrous metals
(can be used with aluminum and stainless)
No electrode stub loss
Disadvantages of MIG
 Machine
cost more than stick
welder
 Difficult to use in hard to get
places
MIG
 Gas
pressure of 20 psi
 Gas mixture:
75%
argon
25% CO2
Purpose of Gas Mixture
 Keeps
nitrogen and oxygen out
of weld bead
 Increases penetration
 Reduces spatter
MIG
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Wire size: 0.035 inches
Mild steel copper coated electrode
Welding Jelly can be used to prevent
spatter from sticking to tip
Use at least a number 10 shade lenses,
12 is sometimes recommended.
Almost all MIG welding is performed in the
direct current electrode positive mode
(DCEP)
3 adjustments must be in balance to
achieve a quality weld
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Voltage control
 18-21
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Wire feed speed
 180
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volts
- 240
Shielding gas flow rate
 15-20
psi