Striking an arc means to establish a welding current across a gap between the welding electrode and the base metal.1 Welding training programs may offer instruction in how to strike the arc in different types of welding methods, including TIG welding.
What is TIG welding? And what are the 3 ways to strike the arc in TIG welding?
What Is TIG Welding?
Ionized gas is a good conductor of electricity. TIG welding stands for tungsten inert gas welding. In this welding method, tungsten gas can be ionized by applying heat and/or applying high frequency voltage.2
Tungsten has an extremely high melting point. This means that a tungsten electrode will get very hot but it won’t melt and become a part of the weld, like some other welding processes. Because a TIG electrode does not melt, it is considered a “non-consumable” type of welding. MIG welding and stick welding, on the other hand, are considered “consumable” types of welding because the electrode melts and becomes part of the filler metal.3
TIG welding is a type of welding used to weld thin metals. TIG welding can be used in pipeline welding and with exotic metals. Usually, TIG welding involves metals under ¼ inch, except in cases of aluminum and magnesium.4 Striking an arc in TIG welding can be less intense and much quieter than MIG or stick welding.5
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3 Ways to Strike an Arc in TIG Welding
There are three ways to strike an arc in TIG welding:
1. Scratch Start
Scratch starting in TIG welding is similar to scratching a match across a matchbox.6 A TIG electrode is attached to a low-cost inverter welder machine that has been designed for stick welding.7 After turning the gas on, the arc must be established by sweeping the electrode across the plate or base metal to make contact.8
Scratch start can be used on low-cost machines to initiate an arc.8 This means any DC stick welder can be used as a TIG welder. Scratch start can be a good way to get started with TIG welding and is the oldest method for starting an arc.6
It can be difficult to start and end the arc without sticking and leaving tungsten on the metal.8 The tungsten gets hot very quickly as the arc is struck and can break off into small bits that are left on the weld, which could cause structural problems later.6
2. Lift Arc (Lift TIG)
Lift arc starting may look very similar to scratch starting, but it is not the same. Like scratch starting, lift arc starting uses a tungsten electrode to make contact with the base metal. But the difference is that the electrode is brought down very quickly and lightly, and then quickly lifted to “draw” up the arc.6
Though they may at first look similar, lift arc starting is very controllable, creating consistent, positive arc starts.7,9 This method also uses DC output rather than a high frequency current.9 As an alternative to high frequency starting, lift arc starting can be used any time there are problems with frequency in the area, such phone or computer problems, or if you are near an airport or tower.8
Lift arc may not be 100% clean and the tungsten can still get contaminated, but generally less so than scratch starting. Lift arc starting should not be used with aluminum because tungsten and aluminum already have a natural affinity for each other.6
3. High Frequency Start (HF Arc Start)
High frequency (HF) start can be a popular option for TIG welding.6 In this method, the tungsten electrode is connected to a machine that generates a high frequency arc. This high frequency arc ionizes the air and bridges the gap between the tungsten electrode and the base metal for a non-contact start.6
The arc created by HF starting is generally very clean and does not leave tungsten contamination.6 Some welding procedures specify a non-contact starting method, such as pressure vessels and process piping, so this would be a good method to use.9 This can also be a good method to use for TIG welding aluminum.6
While HF starting is sometimes considered the best option for TIG welding, it is more expensive. Not all welding systems provide high frequency starts because incorporating HF components may add hundreds of dollars in cost to a power source.9
Practice Striking the TIG Arc in Welding Training
Would you like to practice striking an arc in TIG welding? Signing up for welding classes could give you the tools and instruction you desire. Tulsa Welding School offers hands-on experience in its welding training programs. Call (855) 237-7711.