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Tig Welders & Tig Welding

When do you use TIG?

The TIG (Tungsten Inert Gas) welding process (also known as gas tungsten arc welding, GTAW, or HELIARC, a trade name of Linde) generates heat from an electric arc maintained between a non consumable tungsten electrode and the part being welded.

TIG  welding is a manual welding process that uses a non-consumable electrode made of tungsten, an inert or semi-inert gas mixture, and a separate filler material.

Especially useful for welding thin materials, TIG welding is characterized by a stable arc and high quality welds. It requires good operator skill and is relatively low-speed. It's useful on many weldable materials, but is often applied to stainless steel and light metals.

Tig welder pricing varies by the kind of welder you're looking for and the welding performance you expect from it. I've also thrown together a listing of the welders people have put together at eBay. Some are new, others used. It's a worthwhile reference. eBay's TIG Welder Listings.

The history of Tig welding machines

This process was developed for the aircraft industry back in the early '40s. TIG may be used without the addition of a filler metal or a separate wire filler metal can be added into the puddle when additional material is required, much like the process in oxy-acetylene welding.

The puddle, the tungsten electrode and the filler rod are protected from atmosphere by a shield of inert gas to prevent rapid oxidation of the weld and surrounding metal. Argon is the most widely utilized gas. Because the gas shield does not produce the slag that normally is created by flux, the danger of slag inclusion in the weld metal is eliminated. Also, due to the slow speed of the TIG process, gases and other impurities escape to the surface of the puddle before solidification occurs, eliminating pockets called "Porosity" common in weld processes that employ gas shielding but have greater travel speeds than the TIG process.

Process and heat

TIG also produces a welding heat is that is confined between the weld and base metal at the point of fusion and produces a narrow heat affected zone. This reduces stress, cracking and distortion in the finished weld. Spatter is not produced by this process, leaving the weld and surrounding metal clean. Because of the lack of spatter and flux smoke, the TIG process allows the operator a clear view of the weld puddle. The torch body in most cases is small enough that the operator can hold it in the same manner as he would hold a pencil allowing easier manipulation.

Power sources

The TIG welding power source is constant current, either AC, DC, or combination AC/DC. Type of metal determines which type is used. DC (direct current) is most normally used for TIG welding of stainless steels and mild and low alloy steels. AC (Alternating current) is used for TIG welding of aluminum. Surface oxidation is automatically removed by the action of the arc each time the electrode becomes positive, (60 times per. second). Because AC crosses over the zero volt point 120 times per second (once going positive and once going negative each cycle), the arc shuts off 120 times per second. To keep the arc going when using AC, a high frequency "arc stabilizer" is used. The high frequency also allows the start of an arc in DC mode without having to "strike" an arc, thereby reducing the possibility of tungsten contamination. If the electrode accidentally touches the weld pool, it becomes contaminated and must be cleaned immediately to prevent weld contamination. TIG requires an extremely clean surface to weld successfully and is a fairly slow operation.

On the plus side, TIG produces high quality work and does not generate slag or spatter. The welder can adjust the heat input while welding by using foot or hand amperage controls.

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