The TIG welding torch is a critical part of the TIG process. It is the point at which the arc is created and whilst the majority of heat goes into the arc the TIG welding torch is subjected to high heat levels.
As the TIG torch is held by the operator it must remain cool whilst still being easily manoeuvrable and compact in size. This heat is removed from the torch by either air/gas cooling or water cooling.
Where TIG torches are required for high production or use high amperage then these would normally be water cooled and where lower amperage or lighter duty welding is required these would normally be air cooled.
Air/Gas cooled TIG torches require no additional cooling other than the surrounding air and gas flow. Higher current air cooled TIG torches are often larger and less flexible to use than water-cooled torches.
The cable carrying the welding current must be heavier than the cable in water-cooled torches.
Water-cooled TIG torches are designed so that water is circulated through the torch cooling it and the power cable. The power cable is contained inside a hose and the water returning from the torch flows around the power cable providing the necessary cooling.
This method of cooling means the power cable can be relatively small, making the entire cable assembly light and easily manipulated. Care must be taken when using a water cooled torch that a lack of coolant or no coolant at all will cause the polyethylene or braided rubber sheath to
melt or possibly the power cable will melt. Always check the flow rate required to cool the TIG welding torch.
TIG Welding Torch Components
TIG Torch Body / Head
The torch body is usually covered by a rigid phenolic material or a rubberised covering. They can be rigid or flexible variants, with or without valves.
Collet Body
The TIG collet body screws into the torch body. It is replaceable and is changed to accommodate different size tungsten electrodes and their respective collets.
Collet
The tungsten welding electrode is held in the TIG welding torch by the collet. The collet is usually made of copper or a copper alloy. The collet’s grip on the electrode is secured when the torch back cap is tightened in place. Good electrical contact between the collet and tungsten electrode is essential for good current transfer.
Gas Lens Body
A gas lens is a device that can be used in place of the normal collet body. It screws into the TIG torch body and is used to reduce turbulence in the flow of shield gas and produce a stiff column of undisturbed flow of shielding gas. A gas lens will allow the welder to move the nozzle further away from the joint allowing increased visibility of the arc.
A much larger diameter nozzle can be used which will produce a large blanket of shielding gas. This can be very useful in welding material like titanium. The gas lens will also enable the welder to reach joints with limited access such as inside corners.
Ceramic Cup
Gas cups are made of various types of heat resistant materials in different shapes, diameters and lengths. The cups are either screwed onto the collet body or gas lens body or in some cases pushed in place. Cups can be made of ceramic, metal, metal-jacketed ceramic, glass or other materials. Ceramic is the most popular but can be easily broken.
TIG Tungsten Welding Electrodes
TIG welding electrodes are a ‘non consumable’ as it is not melted into the weld pool and great care should be taken not to let the electrode contact the welding pool to avoid weld contamination. This would be referred to as tungsten inclusion and may result in weld failure. Electrodes will often contain small quantities of metallic oxides which can offer the following benefits:
• Assist in arc starting • Improve current carrying capacity of the electrode • Reduce the risk of weld contamination • Increase electrode life • Increase arc stability
Oxides used are primarily zirconium, thorium, lanthanum or cerium. These are added usually 1% - 4%.
For more information on the different types of tungstens please see our blog post
