Introduction to practical application of wire feed welding

MIG – Metal Inert Gas Welding  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 Disadvantages 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  Welding power source expensive  Shielding gas expensive  Higher electrode wire cost  Most machines require three- phase input power  Not as versatile as SMAW for maintenance 4Welding cast iron 4Cutting 4Carbon arc torch applications

 Stationary  Portable  Integrated  Nonintegrated  Advantages and Disadvantages  Adjustments

 Containers  Regulators  Ball and Dial indicators  Gases Materials  Carbon dioxide Steel  Argon Stainless Steel  Helium Aluminum  Oxygen

 Types  Integrated  Component  Advantages  Disadvantages  Parts 4Feed motor 4Drive Assembly 4Spool Assembly 4Wire speed control 4Computer controller

 Gun Types 4Inline 4Handle  Gun Characteristics 4Wire Guide 4 Tips 4Shielding Gas Nozzle 4Insulator 4Internal Gun wire driver  Whip Characteristics 4Shielding Gas 4Sheath 4Liner 4Power feed

 Wire Types 4Hard Wire (Solid) 4Dual Shield 4Flux Core  Polarity 4DCRP 4DCSP  Advantages  Disadvantages  Advantages  Disadvantages

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TIG – Tungsten Inert Gas Welding

TIG  Welding process uses a non-consumable tungsten electrode to form an arc which is shielded by inert gas  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  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  Arc voltage is greater  Hotter arc  Deeper Penetration  Fast Speed  Less Distortion  May spatter more than Argon  Carbon Dioxide  Cooling effect  Low cost  Produces Spatter  Deep penetration  Not same inert characteristics as Argon and Helium