Sunday, January 18, 2009

MIG welding


Gas Metal Arc Welding (GMAW) is frequently referred to as MIG welding. MIG welding is a commonly used high deposition rate welding process. Wire is continuously fed from a spool. MIG welding is therefore referred to as a semiautomatic welding process.




MIG Welding Benefits

  • All position capability
  • Higher deposition rates than SMAW
  • Less operator skill required
  • Long welds can be made without starts and stops
  • Minimal post weld cleaning is required

MIG Welding Shielding Gas

The shielding gas, forms the arc plasma, stabilizes the arc on the metal being welded, shields the arc and molten weld pool, and allows smooth transfer of metal from the weld wire to the molten weld pool. There are three primary metal transfer modes:

  • Spray transfer
  • Globular transfer
  • Short circuiting transfer

The primary shielding gasses used are:

  • Argon
  • Argon - 1 to 5% Oxygen
  • Argon - 3 to 25% CO2
  • Argon/Helium

CO2 is also used in its pure form in some MIG welding processes. However, in some applications the presence of CO2 in the shielding gas may adversely affect the mechanical properties of the weld.


WELD DISCONTINUTIES:
  • Undercutting
  • Excessive melt-through
  • Incomplete fusion
  • Incomplete joint penetration
  • Porosity
  • Weld metal cracks
  • Heat affected zone cracks
MIG Welding Problems
  • Heavily oxidized weld deposit
  • Irregular wire feed
  • Burnback
  • Porosity
  • Unstable arc
  • Difficult arc starting
***********************************************************************************



3 comments:

  1. The shielding gas, forms the arc plasma, stabilizes the arc on the metal being welded, shields the arc and molten weld pool, and allows smooth transfer of metal from the weld wire to the molten weld pool. There are three primary metal transfer modes:Jay

    ReplyDelete
  2. These lenses have proved over time to improve the productivity of any welding job. This type of lens give the operator a better control over the welding work and reduces the possibility of any arc flash from reaching the eye. This content

    ReplyDelete
  3. I think this is an informative post and it is very useful and knowledgeable. therefore, I would like to thank you for the efforts you have made in writing this article. machine shop pros

    ReplyDelete