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WHAT IS PLASMA ARC WELDING?


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plasma welding

Process characteristics

Plasma welding is extremely almost like TIG because the arc is made between a pointed tungsten electrode and therefore the workpiece. However, by positioning the electrode within the body of the torch, the plasma arc is often separated from the shielding gas envelope. Plasma is then forced through a fine-bore copper nozzle which constricts the arc. Three operating modes are often produced by varying bore diameter and plasma gas flow rate:

Microplasma: 0.1 to 15A

The microplasma arc is often operated at very low welding currents. The columnar arc is stable even when arc length is varied up to 20mm.

Medium current: 15 to 200A

At higher currents, from 15 to 200A, the method characteristics of the plasma arc are almost like the TIG arc, but because the plasma is constricted, the arc is stiffer. Although the plasma gas flow is often increased to enhance weld pool penetration, there’s a risk of air and shielding gas entrainment through excessive turbulence within the gas shield.

Keyhole plasma: over 100A

By increasing welding current and plasma gas flow, a really powerful plasma beam is made which may achieve full penetration during a material, as in laser or beam welding. During welding, the opening progressively cuts through the metal with the molten weld pool flowing behind to make the weld bead under physical phenomenon forces. This process is often wont to weld thicker material (up to 10mm of stainless steel) during a single pass.

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