TIG Welding: Scratch Start, Lift Start, or High-Frequency?

Man TIG welding a stainless steel pipe

TIG Welding: Scratch Start, Lift Start, or High-Frequency?

When considering a TIG welding machine, the number of features, modes, and settings can be daunting. One of the most critical to understand, however, is the arc initiation method a machine is designed to utilize. These are the three types of arc starting methods:

The Scratch Start Method in TIG Welding

The scratch start method is the oldest, simplest, and most difficult to use. With the scratch start method, welders must manually “scratch” their electrode across the workpiece, similar to This Photo by Unknown Author is licensed under CC BY SA striking a match.

This is not very user-friendly and takes quite a bit of practice, as the electrode tends to stick to the workpiece, leading to point loss on the electrode and contamination of the weld. When using this method, the operator must also manually terminate the arc by pulling away from the workpiece. Gas is controlled by way of a valved torch head instead of being controlled by a gas solenoid in the machine. This arc starting method will only be found on older machines, entry-level machines, and machines converted from SMAW operation. If you are new to TIG welding, machines utilizing scratch start will be difficult and frustrating to learn on.

The Lift Start Method in TIG Welding

Lift start is a common method used on many TIG welding systems. To use this method, the welder will touch the electrode to the work piece, depress the foot pedal or finger switch, and “lift” the torch off of the workpiece to form an arc.

This arc initiation method is much smoother than scratch start and will not disrupt nearby sensitive electronics like high-frequency start circuitry can. Lift start is very often found on multi-process machines where the TIG process may only be used sparingly.

The High-Frequency Start Method in TIG Welding

This is the most common arc initiation method for industrial TIG welders. High-frequency start is the only true “touchless” method of arc initiation in TIG welding and is sometimes required in applications where any contamination of the weld puddle would result in a structural defect, most notably aluminum pipe work. High-frequency arc starting is also the most user-friendly method, as the welder may simply hold the torch where they want to start an arc and depress a foot pedal or finger switch. Machines which utilize scratch or lift start can be upgraded by adding on a module with high-frequency capability.

High-frequency systems can cause issues with nearby televisions, radios, computers, lighting, pacemakers and other sensitive electronics and machines equipped with high-frequency arc starting capability will usually have the option to switch to lift start when it is needed.

Scratch start, lift start, and high-frequency start all have their pros and cons, but it’s definitely important to know the difference to know when to choose each method for MIG welding.

For more information about TIG Welding practices, you can read more of our guides & blogs here at American Torch Tip.

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