Shielded Metal Arc Welding Process

Shielded Metal Arc Welding Process

  • Shielded Metal Arc Welding Process is also called Flux shielded metal arc welding.
  • It is an arc welding process where coalescence is produced by heating the work piece with an electric arc set up between the flux coated electrode and the work piece.
  • Due to arc heat, the flux covering decomposes and performs functions of arc stability, weld metal protection, etc.
  • The electrode itself melts and supplies the necessary filler metal.

Principle of Shielded Metal Arc Welding Process:

  • Required heat for welding is obtained from the arc struck between the coated electrode and the work piece.
  • By employing higher or lower currents, the arc temperatures and thus arc heat can be increased or decreased.
  • Generally, the arc temperature is about 2400 “C to 2600 ‘C.
  • A high current with a smaller arc length produces very intense heat.
  • The arc melts the electrode and the work piece.
  • Material droplets are transferred from the electrode to work piece through the arc and are deposited along the welded joint.
  • The coaling of flux melts and produces a gaseous shield and slag to prevent atmospheric contamination of the molten weld metal.
  • Figure shows the working of flux shielded metal arc welding.

Advantages of Shielded Metal Arc Welding Process

  • It is the simplest of all arc welding processes.
  • The equipment is portable and less expensive.
  • Various metals and their alloys can be welded.
  • Welding can be done in any position with high weld quality.

Limitations of Shielded Metal Arc Welding Process

  • Due to limited length of electrode and brittle flux coating on it, mechanisation is difficult.
  • It is a slow process.
  • Because of flux coated electrodes, the chances of slag entrapment and other related defects are more.
  • Welding control in this process is difficult.

Applications of Shielded Metal Arc Welding Process

  • Used for all commonly used metals and their alloys.
  • It is used as a fabrication process and for maintenance and repairs.
  • Also used in,

                   Air receiver, boiler and pressure vessel fabrications

                   Automotive and aircraft industry

                   Ship building and bridge construction.

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