New year… new edition of our monthly column on welding!
Today we are talking about TIG (Tungsten Inert Gas) welding. A technique that is particularly suitable when a high level of aesthetics is required.
How does it work?
Heat is produced by an electric arc between an infusible tungsten electrode and the material that needs to be welded, in an inert gas atmosphere.
The most common gases are Argon and Helium, which are used separately or in a mixture.
Welding is carried out by fusing the edges of the piece that needs to be welded and manually adding the filler material using a welding rod.
Types of ignition
The welding arc can be triggered in three ways:
Scratch Start, when the electrode tip touches the surface, generating a short circuit.
Lift Arc, when the electrode tip, at a very low current level, is placed on the surface and lifted just slightly.
HF Ignition, when the electrode does not touch the surface that is being welded. The electric arc is generated by the high voltage at high frequency on the torch, and it is in this way that a myriad of sparks ionise the gaseous atmosphere between the electrode and the workpiece, triggering a passage of current.
Which metals can be welded?
Stainless steel, aluminium, cupronickel, copper, iron and special alloys can be welded.
TIG welding requires a great deal of manual skill. This is because when using the welding rod the for addition of filler material, one must prevent the electrode from sticking to the surface. Moreover, minimize the risk of contamination of the weld pool by tungsten, especially with the Scratch Start.
Due to the high precision and slow process, this technique is therefore suitable for visible welding on small material thicknesses.
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