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Plasma to the fore

Connect, no.130, May/June 2004, p.8

Polysoude 600PC plasma and hot wire power source
Polysoude 600PC plasma and hot wire power source

New state of the art plasma welding kit from Polysoude is the latest addition to TWI's arsenal of arc welding equipment.

It's designed to support member companies in applying the process to manufacturing, and towards investigating new applications.

Plasma welding is very similar to TIG as the arc is formed between a pointed tungsten electrode and the workpiece. However, the electrode is positioned within the body of the torch and the ionised plasma gas is then forced through a fine-bore copper nozzle. This constricts the arc to create a very powerful plasma beam which can achieve full penetration in a material in the keyhole mode.

During welding, the hole progressively cuts through the metal with the molten weld pool flowing behind to form a weld bead under surface tension forces. This process can be used to weld thicker material ( eg up to 10mm of stainless steel) in a single pass.

The Polysoude 600PC plasma welding system also has a hot wire facility. This equipment is fully programmable and has the capability to close the keyhole, as maybe required for orbital welding, by sloping out the welding current and plasma gas at the end of the weld. Pulsed welding parameters, wire feed, oscillation and welding speed parameters are all controlled by the equipment.

This kit complements a powder plasma arc welding facility also within the arc welding section. In this relatively new process development by Plasma Modules Oy, a powder consumable is fed into the arc through the welding torch.

The technique, which may be used manually, is suitable for fabrication and repair of stainless steels and nickel alloys, particularly alloys for which a wire or rod consumable is expensive or unobtainable. It is also suitable forrobotic applications.

These welding systems have added significantly to the capabilities of the arc welding section. Plasma welding projects are being carried out for individual member companies and also under the Core Research Programme. To find out more or to discuss applications for plasma welding, call Geoff Melton or Richard Jones. or

For more information please email: