TIG Welding

Tips and techniques for better welding

Tungsten inert gas (TIG) welding, also known as gas tungsten arc welding (GTA welding or GTAW), is often used in aircraft applications.

TIG welding provides a clean, strong weld joint that makes it ideal for assembling and repairing various aircraft components. In this article, we will discuss the basic theory of TIG welding and discuss some tips for better TIG welding results.

Basic Theory

In TIG welding, a non-consumable tungsten electrode is used to establish an arc on the base metal. The heat of the arc produced melts the base metal and produces a weld pool. In contrast to normal stick welding, when TIG welding, an inert gas shields the weld area in order to prevent air from contaminating the weld. This shielding gas prevents oxidation of the tungsten electrode, the molten weld puddle, and the heat-affected zone adjacent to the weld bead.

In a typical TIG setup, an AC/DC welding machine is used with a flow of shielding gas. The shielding gas goes through a regulator and flow meter and on to the torch. The torch has a collet/collet body combination that holds the electrode. A heat-resistant cup or ceramic nozzle surrounds the electrode and controls the gas shield. In addition, water-cooled TIG machines are available for high-amperage welding applications.

Personal Protective Equipment

Although TIG welding does not produce all of the metal spatter that is associated with stick welding, it still generates intense heat and light. In fact, the clearer atmosphere around the TIG arc can cause up to twice the amount of infrared and UV rays compared to normal arc welding.

Any exposed skin will be burned similar to an extreme sunburn. Welders should wear personal protective equipment such as a welding helmet, welder’s protective gloves, and clothing. Of course, fire-resistant cloth and leather clothing and accessories are recommended. A word of caution — cotton should not be used as it does not provide sufficient protection and it deteriorates quickly under the infrared and UV rays produced by the TIG welding process. As a tip, dark clothing should be used to reduce reflection of light behind the helmet.

Other Safety Precautions

The following general precautions should be observed to protect you and co-workers from the hazards associated with TIG welding:

Ensure electrical connection leads are in good condition and tight prior to use. They should be protected to prevent accidental damage from hangar traffic.

Make sure you have adequate ventilation. Since TIG welding uses inert gases to shield the weld area, if it is used in an enclosed area it can displace breathing air and can be hazardous. Ensure your work area has proper ventilation. In addition, ozone is produced during the welding process. Anyone who has been around a TIG welder knows the sweet smell associated with TIG welding. But high levels of ozone can be hazardous. The amount of ozone produced varies with the type of electrode used, amperage, and argon flow. In poorly ventilated areas, ozone levels can increase to irritating or harmful levels. Whenever possible, draw fumes and contaminated air away when welding.

Flammable materials should not be carried in clothing pockets. Shielding curtains should be placed around all jobs so that workers in adjacent areas are not exposed to the welding arcs.

Shielding Gas

In TIG welding, the gas used to shield the welding arc and hot metals is an inert gas. Inert gases are gases whose atomic structures do not allow them to react with metals or other gases. Argon, helium, or an argon-helium mixture is used as the inert gas in TIG.

Argon is a relatively heavy gas. It has several benefits when used in TIG welding. It requires a lower arc voltage than other shielding gases for a given arc length and current used (ideal for thin metal welding). It also provides easier arc starting. Its heavier weight as compared to helium provides for good shielding with lower flow rates.

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