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

Man TIG welding a stainless steel pipe

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 the machine uses. In this article, we will discuss the three types of TIG welding techniques used for starting an arc.

The Scratch Start Method in TIG Welding

The scratch start method is the original arc starting TIG welding technique. With the scratch start method, welders must manually “scratch” their electrode across the workpiece. The motion is often compared to striking a match.

This arc starting method is not very user-friendly, and it can take quite a bit of practice. The electrode tends to stick to the workpiece, which leads to point loss on the electrode and contamination of the weld. To avoid getting the electrode stuck to the workpiece, it is important to maintain control over the torch at all times. When using this method, the operator must also manually terminate the arc by pulling away from the workpiece.

As opposed to a gas solenoid in the machine, a valved torch head controls the gas in this TIG welding technique. 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 techniques, machines utilizing scratch start may be difficult and frustrating to learn on.

The Lift Start Method in TIG Welding

Lift start is a common TIG welding technique used on many welding systems because it is very user friendly. 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 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” TIG welding technique for arc initiation. Applications where any contamination of the weld puddle would result in a structural defect, most notably aluminum pipe work, will usually require high-frequency start..

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. For machines that use scratch or lift start, adding on a module with high-frequency capability can upgrade the machine.

The downside is that these arc starting systems can cause issues with nearby televisions, radios, computers, lighting, pacemakers and other sensitive electronics. Fortunately, 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. Knowing the difference between these arc starting TIG welding techniques will help you choose the best method for your project.

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

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