Twin carbon arc welding
Encyclopedia
Unlike single carbon arc welding
, in twin carbon arc welding the arc
is maintained between two carbon electrode
s held in a special holder. Current is switched on and by operating the mechanism of arc length adjustment the two electrodes are brought closer. The two electrodes touch momentarily, then separate and thus an arc is established.
The size of the arc depends upon the distance between the electrode tips, electrode diameters and the welding current
. The heat input to the job can be varied by changing the arc size or the distance between the arc and workpiece. After striking the arc, welding can be carried out in the same way as in TIG welding
process.
An AC
supply is recommended for twin carbon arc welding. In case a DC
supply is used, the positive electrode will disintegrate and consume at a much faster rate as compared to negative electrode, because two-thirds of the total heat is generated at the positive pole. This will produce an unstable arc and require frequent adjustment of the electrodes. In AC welding, because of alternate reversals of polarity, both the electrodes will be affected equally and present no problem.
The electrodes employed for twin carbon arc welding are approximately of the same diameter as the workpiece thickness. The magnitude of arc current required for welding depends upon both electrode diameter and plate thickness. For example, an 8 mm diameter electrode will need about 65 amps
to weld a mild steel sheet of thickness 3.5 mm and 80 Amps to weld a sheet of 6 mm thickness.
Twin carbon arc welding, though more complex than single carbon arc welding, possesses the advantage that arc is independent of the job and can be moved anywhere without getting extinguished. Moreover, the workpiece is not a part of the electrical circuit.
Carbon arc welding
Carbon arc welding is a process which produces coalescence of metals by heating them with an arc between a nonconsumable carbon electrode and the work-piece. It was the first arc-welding process ever developed but is not used for many applications today, having been replaced by twin-carbon-arc...
, in twin carbon arc welding the arc
Arc welding
Arc welding is a type of welding that uses a welding power supply to create an electric arc between an electrode and the base material to melt the metals at the welding point. They can use either direct or alternating current, and consumable or non-consumable electrodes...
is maintained between two carbon electrode
Electrode
An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit...
s held in a special holder. Current is switched on and by operating the mechanism of arc length adjustment the two electrodes are brought closer. The two electrodes touch momentarily, then separate and thus an arc is established.
The size of the arc depends upon the distance between the electrode tips, electrode diameters and the welding current
Electric current
Electric current is a flow of electric charge through a medium.This charge is typically carried by moving electrons in a conductor such as wire...
. The heat input to the job can be varied by changing the arc size or the distance between the arc and workpiece. After striking the arc, welding can be carried out in the same way as in TIG welding
Gas tungsten arc welding
Gas tungsten arc welding , also known as tungsten inert gas welding, is an arc welding process that uses a nonconsumable tungsten electrode to produce the weld...
process.
An AC
Alternating current
In alternating current the movement of electric charge periodically reverses direction. In direct current , the flow of electric charge is only in one direction....
supply is recommended for twin carbon arc welding. In case a DC
Direct current
Direct current is the unidirectional flow of electric charge. Direct current is produced by such sources as batteries, thermocouples, solar cells, and commutator-type electric machines of the dynamo type. Direct current may flow in a conductor such as a wire, but can also flow through...
supply is used, the positive electrode will disintegrate and consume at a much faster rate as compared to negative electrode, because two-thirds of the total heat is generated at the positive pole. This will produce an unstable arc and require frequent adjustment of the electrodes. In AC welding, because of alternate reversals of polarity, both the electrodes will be affected equally and present no problem.
The electrodes employed for twin carbon arc welding are approximately of the same diameter as the workpiece thickness. The magnitude of arc current required for welding depends upon both electrode diameter and plate thickness. For example, an 8 mm diameter electrode will need about 65 amps
Ampere
The ampere , often shortened to amp, is the SI unit of electric current and is one of the seven SI base units. It is named after André-Marie Ampère , French mathematician and physicist, considered the father of electrodynamics...
to weld a mild steel sheet of thickness 3.5 mm and 80 Amps to weld a sheet of 6 mm thickness.
Twin carbon arc welding, though more complex than single carbon arc welding, possesses the advantage that arc is independent of the job and can be moved anywhere without getting extinguished. Moreover, the workpiece is not a part of the electrical circuit.
External links
- http://www.fortunecity.com/village/lind/247/weld_book/Ch6.htm