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WELDING

WELDING. Harkness career center. What is MIG?. Metal Inert Gas (MIG) MIG is an arc welding process that uses a continuous solid wire electrode for the filler metal and a shielding gas to protect the weld zone. The molten puddle is shielded by an external shielding gas ARGON/CO2 MIX CO2.

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WELDING

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  1. WELDING Harkness career center

  2. What is MIG? • Metal Inert Gas (MIG) • MIG is an arc welding process that uses a continuous solid wire electrode for the filler metal and a shielding gas to protect the weld zone. • The molten puddle is shielded by an external shielding gas • ARGON/CO2 MIX • CO2

  3. Welding Safety • Leather gloves • Sleeves • Full face helmet • Welding shade 9-14 • Arc weld can be 8 times brighter than the sun! “ welders flash”

  4. MIG welder setup • The cart- secures all • the components • The tank- filled with an • inert gas 2k to 3k psi • The regulator- controls tank • pressure 15 to 20psi • The welder • - converts AC voltage • to DC voltage • - controls the wire speed • and heat

  5. Welder schematic

  6. Regulator • The regulator reduces tank • pressure • The gauge closest to the • tank reads tank pressure • -The gauge closest to the hose • outlet reads working pressure • -Working pressure should be • 15 to 20 psi • -The adjuster screw should • backed off when not in use

  7. Ground clamp • -Supplies the welded metal a • ground • -The surface must be clean and • rust free • Should be as close to the weld • as possible

  8. Welding gun • Gun housing • Electrical insulator • Positive electrode and gas • discharge • Contact tube • Fill wire “electrode”

  9. MIG gun and weld area

  10. Welding process

  11. MIG PROCESS

  12. GUN MOVEMENTS

  13. Welding Flaws Kalpakjian

  14. -Welding Flaws at the Underside of the weld -Incomplete Penetration (not enough heat input) www.mig-welding.co.uk www.ndt-ed.org/EducationResources

  15. Distortion from Welding Processes • Non-uniform shrinkage of weld bead • Difficult to maintain alignments • Solution: Rigid fixtures, pre-compensate for warping, loose tolerances Kalpakjian

  16. Types of Joints Kalpakjian

  17. Weld bead profile: Convex or Concave? • Solidification of molten bead leads to shrinkage • Shrinkage of a concave bead leads to tension on surface  tends to crack • Shrinkage of a convex bead leads to compression on surface  does not crack • Generally, slightly convex beads are preferred. Lincoln Electric

  18. WELDING WITHOUT GAS

  19. Millermatic 35 Set heat 1—6 (Turn & Pull) Set wire speed Usually around 50 Adjust heat and speed as needed. Blue Hobart Determine type of metal and position Lift cover and determine welder preset selection for heat and speed. Adjust machine Fine adjustment wire speed and heat to individual needs. Wire WelderMAKE SURE TO TURN ON FLOW GAGES!!

  20. Wire Welder Problems • 1. Make sure your turn on the flow gages. • Setting to around 25—30 • 2. Make sure your hoses are straight • 3. Popping Noise—Adjust wire speed down. • 4. Check wire tips • 5. Dip wire tips into nozzle lubricant • 6. Make sure you have good penetration. • Internet Site: http://www.lincolnelectric.com/knowledge/articles/content/gmaw.asp

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