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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 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 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 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