Electrode in TIG welding

Electrode in TIG welding

In TIG welding, tungsten refers to the element used on the electrode. The function of the electrode is to serve as one of the electric terminals which supplies the heat required to the weld. Care must be taken so that the tungsten electrode does not come contact with the weld pool in any way in order to avoid its contamination resulting on faulty weld. Pure tungsten is less expensive and will carry less current. Some other elements may be added to the tungsten, like cerium, lanthanum, thorium and zirconium creating electrode alloys in order to improve arc stability, emissivity and bring higher mellting points. The electrode may contain 1 to 2% thoria(thorium oxide) mixed along with the core tungsten or tungsten with 0.15 to 0.40% zirconia (zirconium oxide).The thoriated tungsten electrodes carry high current and more desirable as they can strike and maintain a stable arc. The zirconia added with tungsten is better than pure tungsten but inferior to thoriated tungsten electrode.

In Tungsten Inert Gas (TIG) welding, the electrode plays a crucial role in the welding process. The electrode used in TIG welding is primarily made of tungsten, which is a hard and heat-resistant metal.

Here are few major points about the electrode in TIG welding:

Tungsten Selection:

TIG electrodes are available in various types of tungsten, each with specific characteristics suitable for different applications. The most commonly used tungsten types are pure tungsten (WP), thoriated tungsten (WT20), ceriated tungsten (WC20), lanthanated tungsten (WL20), and zirconiated tungsten (WZr). The selection depends on factors such as the type of material being welded, welding current, and desired arc stability.

Non-Consumable Electrode:

Unlike in other welding processes, TIG electrodes are non-consumable. This means that the electrode does not melt during the welding process and remains intact. It acts as a heat-resistant conductor, transferring the current to the welding arc.

Pointed or Balled Tip:

The tip of the tungsten electrode can be shaped in two ways: pointed or balled. A pointed tip is typically used for welding thinner materials, providing better arc control and more precise welding. A balled tip is created by applying more current and forms a rounded shape, suitable for welding thicker materials or when a wider weld bead is desired.

Electrode Size:

Tungsten electrodes come in various sizes, ranging from 0.5 mm to several millimeters in diameter. The size of the electrode depends on the welding current and the thickness of the material being welded. Thicker electrodes are used for higher currents and thicker materials.

Inert Gas Shielding:

TIG welding employs an inert gas, such as argon or helium, to shield the weld pool from atmospheric contamination. The electrode’s non-consumable nature ensures that it remains unaffected by the welding process and the shielding gas.

Electrode Holder:

The tungsten electrode is held in a specialized collet or collet body within the TIG torch. The electrode holder provides electrical contact to the electrode, allowing the current to flow through it.

Preparation and Sharpening:

Tungsten electrodes need to be properly prepared and sharpened before welding. The preparation involves removing any contaminants, such as dirt or oils, from the electrode’s surface. Additionally, the electrode tip needs to be sharpened to a specific angle, typically between 15 and 30 degrees, depending on the application. A properly sharpened electrode allows for better arc control and stability.

Gas Flow:

The TIG welding process relies on a constant flow of inert gas to shield the weld zone from oxygen and prevent contamination. The electrode design plays a role in optimizing gas flow. Some electrodes have built-in channels or grooves to improve gas distribution, ensuring effective coverage of the weld area.

Color Coding:

To distinguish between different types of tungsten electrodes, manufacturers often use color coding. Each type of electrode may have a different color band painted on the end of the electrode or on the packaging. It helps welders quickly identify the type of electrode they are using.

AC or DC Polarity:

Tungsten electrodes can be used with both alternating current (AC) and direct current (DC) power sources, depending on the welding application. AC is commonly used for welding aluminum and magnesium, while DC is preferred for welding stainless steel, carbon steel, and other metals. The selection of the appropriate electrode type and polarity is important for achieving desired welding results.

Electrode Contamination:

During TIG welding, it is crucial to avoid electrode contamination. Contaminants such as oil, grease, or moisture can cause weld defects, instability, or contamination of the weld pool. Proper storage and handling of electrodes, as well as regular cleaning, are necessary to prevent contamination and ensure consistent welding performance.

Electrode Life:

While tungsten electrodes are non-consumable, they do experience gradual wear during welding. The electrode tip may degrade over time due to factors like high temperatures and repetitive use. Eventually, the electrode may need to be replaced or re-sharpened to maintain weld quality and consistency.

Remember, TIG welding requires skill and practice to master, and the electrode is just one element of the overall welding process. Proper electrode selection, preparation, and handling, along with other factors like current settings, gas flow, and welding technique, contribute to achieving high-quality TIG welds.

Proper selection and preparation of the tungsten electrode are essential for achieving high-quality TIG welds. The electrode’s condition, shape, and size greatly influence arc stability, weld penetration, and overall weld quality.

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