a. High energy density, arc directionality, strong penetration ability, in the case of no beveling, no filler wire can be
Welding through the stainless steel plate of 8 to 10mm thick. Compared with tungsten argon arc welding, in the same weld depth, plasma
arc welding speed is much faster.
b. The quality of the weld is not sensitive to changes in the arc length, this is due to the plasma arc form is close to cylindrical, the dispersion angle is very small,
about 5 °, and straightness is good, the arc length changes in the area of the heated spot has very little impact, easy to obtain a uniform weld shape.
Work
Pieces on the heat area is small, the heat affected zone is narrow, so the thin plate welding deformation is small.
c. The tungsten electrode is shrunk inside the water-cooled copper nozzle, which is impossible to contact with the workpiece, thus avoiding tungsten entrapment in the weld metal.
Arc stirring is good, the molten pool temperature is high, which is conducive to the release of gas in the molten pool.
d. Plasma arc due to the compression effect and high degree of thermal ionization, the current is still very stable when small. Equipped with a new type of electronic
power supply, welding current can be as small as 0.1A, such a small current can also be achieved by stable arc combustion, especially suitable for welding micro
type precision parts.
e. Stable small hole effect can be produced, through the small hole effect, the front side of the welding can be good one-sided welding double-sided molding.
Disadvantages:
a. Weldable thickness is limited, generally below 25mm;
b. Complexity of the torch and control lines, the nozzle's service life is very low;
c. Welding parameters are more welding operator's technical level is required.
Plasma arc welding may be limited in its application for the following reasons.
a. Poor observability of the arc action area. Plasma arc gun structure is complex, not only heavier, manual welding operator is also more difficult to observe the welding area.
b. Double arc disadvantages. The use of transfer arc, when the process parameters are not properly selected, or the nozzle structure is not designed reasonably, or the nozzle
multiple times after the use of damage, it will be in the tungsten electrode - nozzle - between the workpiece to produce a tandem arc, this side arc and the transfer of the arc at the same time
in the presence of the arc is called a double arc. Double arc, indicating that the arc column and the nozzle between the cold gas film has been damaged, the transfer arc current is reduced, which
like this will lead to welding process is not normal, and even burn the nozzle soon.
c. Poor arc accessibility. Because the gun body is relatively large, the tungsten electrode is internalized inside the nozzle, so it is
impotent for some forms of joints.
d. A large investment. Plasma arc welding and cutting equipment is relatively expensive. But its welding or cutting speed, weld
and cutting quality is good, if these factors are taken into account, the cost of its use is not too high.