CARBON ARC WELDING PROCESS

CARBON ARC WELDING PROCESS

The carbon arc welding process is an Arc welding process wherein Fusion is produced by heating with an electric arc struck between a carbon electrode and work peace. Filler metal may be used as per job thickness.welding may be carried out in the air with flux or in an inert atmosphere.

Carbon arc welding process may be classified into two-part

  • Single carbon electrode arc welding
  • Double Carbon electrode arc welding

Single Carbon arc weldingtheweldings

In this process, the arc is initiated between the carbon electrode and the workpiece by touching the electrode with the job.

Twin Carbon arc weldingtwin carbon arc welding process

In the double carbon arc welding process the arc is struck between two carbon electrodes, the workpiece does not become a part of the electrical circuit.

 

parameter

The approximate arc current for single carbon electrode welding for the thickness of

3mm 25 Amp.

6mm 70 Amp.

10mm 125Amp

With graphite electrodes, the above current values should be increased by 5 to 10 %, it may differ as per different materials like:-

Stainless steel 4mm 70Amp

Mild steel 3-4 mm 40 Amp

Copper 3-4 mm 40 Amp

Tig torch can also be used for a single carbon electrode process by using a carbon or graphite electrode.

The approximate arc current for Twin carbon electrode welding for the thickness of

3 mm 65 Amps.

6 mm 80 Amps.

AC supply is preferred for the double carbon arc welding process due to alternate reversals of polarity, which can provide a stable arc as compared to DC supply.

Equipment Required

Power source

For this process, high voltage DC power source, either the DC generator or transformer with rectifier, capable of supplying DC current up to 600 Amps.required.

For the twin carbon electrode, the AC power supply is recommended. when using DC power supply, the positive electrode will decompose and consume at a much faster rate as compared to the negative electrode, because the two-third of the total heat is generated at the positive pole.

Holder carbon arc torch

Air-cooled and water-cooled electrode holders are using for the carbon arc process. When using the above 200 amps current, the water-cooled torch is preferred. TIG torch also may be used with holding a carbon electrode for a single carbon electrode welding process. TIG torch can be used with holding a carbon electrode for a single carbon electrode welding process.

Other Accessories

  • Copper coated(None consumable) carbon or graphite electrode
  • Filler metal

Advantage

  • Easily mechanized
  • Less welding cost
  • Simple equipment requirement

Disadvantage

  • Possibility to transfer carbon from electrode to weld metal
  • Extra care needed when using twin carbon electrode

Applications

  • Aluminum,
  • Nickel,
  • Copper, and
  • Numbers of other alloys.

It can be used for brazing, preheating and post-heating of welded joints, rearing of castings and much other application.

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