Download Mig Welding

Introduction to practical
application of wire feed welding
MIG – Metal Inert Gas Welding
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May be called GMAW (Gas Metal Arc Welding)
Avoid cutting in drafty or windy conditions
Molten pool is shielded by the inert gas envelope
Joints are stronger, more ductile, and more
corrosion resistant
 Flux center wire has slag; Solid wire has no slag,
thus eliminating slag inclusion
 Welded metal does not readily distort
 Power Supply
 Gas Supply
 Wire feeder
 Gun and Whip
 Process
MIG Machine Operation
 Wire is fed at a pre-set rate
 Gas flows at about 35 cubic feet per hour
and is directed around the welding wire for
shielding
Advantages
 Welding can be done in all
positions
 High rates of metal deposition
 Excellent filling ability for
poor-fit joints
 High weld Quality
 No electrode stub loss
 Less distortion due to narrow,
deep weld profile
 Easier process to learn and
use
Disadvantages
 Welding power source
expensive
 Shielding gas expensive
 Higher electrode wire cost
 Most machines require threephase input power
 Not as versatile as SMAW for
maintenance
 Welding cast iron
 Cutting
 Carbon arc torch
applications
 Stationary
 Portable
 Integrated
 Nonintegrated
 Advantages and
Disadvantages
 Adjustments
 Containers
 Regulators
 Ball and Dial indicators
 Gases
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Carbon dioxide
Argon
Helium
Oxygen
Materials
Steel
Stainless Steel
Aluminum
 Types
 Parts
 Integrated
 Feed motor
 Component
 Drive Assembly
 Advantages
 Spool Assembly
 Disadvantages
 Wire speed control
 Computer controller
 Gun Types
Inline
Handle
 Gun
Characteristics
Wire Guide
 Tips
Shielding Gas
Nozzle
Insulator
Internal Gun wire
driver
 Whip Characteristics
Shielding Gas
Sheath
Liner
Power feed
 Wire Types
Hard Wire (Solid)
Dual Shield
Flux Core
 Polarity
DCRP
DCSP
 Advantages
 Disadvantages
 Advantages
 Disadvantages
TIG – Tungsten Inert Gas Welding
TIG
 Welding process uses a non-consumable tungsten
electrode to form an arc which is shielded by inert
gas
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Filler rod may or may not be used
AC or DC
Argon or Helium gas used
Torch needs current and inert gas to weld
Ceramic cone protects electrode
Air cooled or water cooled
Advantages of TIG
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Clean welds – no flux
Weld strength is high
All position use
Visibility is high
Narrow beads – distortion is low
No Spatter
Weld all weldable metals
Best for Aluminum and Magnesium
Best for thinner metal
Disadvantages of TIG
 Skill required – more complicated
 High Frequency interference may occur
(radios, TV’s, etc.)
Inert Gases for Shielding
 Argon
 Cheap – comes from air
 Heavier than air – blankets
weld well
 Provides clean welding of
Aluminum and Magnesium
 Best with AC
 Helium
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Arc voltage is greater
Hotter arc
Deeper Penetration
Fast Speed
Less Distortion
May spatter more than
Argon
 Carbon Dioxide
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Cooling effect
Low cost
Produces Spatter
Deep penetration
Not same inert
characteristics as Argon and
Helium