Common welding related questions we hear. Part 14

Quite often, perspective TIG welder customers who are new to TIG welding often are trying to figure out what type of TIG they need and are confused by the terms of “Lift Start”, “Scratch Start” and “High Frequency Start”. It’s not uncommon for even a pro to mix-up and confuse the terms of “Lift Start” and “Scratch Start” and even occasionally “High Frequency start”. To cover these differences, we’ll take a look at each over the next few blogs and discuss how they are commonly used.

To begin with, it should be made clear that High Frequency start has nothing to do with High Frequency AC welding in the purest use of the term when talking about modern, inverter welders. High Frequency refers to high voltage energy that is created similar to the way an old points style ignition system on an automobile was created. This energy creates a spark similar to that of a spark coming from a spark plug. This spark is used to “Pilot” a path of electricity since it is capable of jumping an air gap for the welding arc.

This means that High Frequency start is a touchless, easy type of start for a beginner to learn and master. This is also the preferred type of start when welding aluminum as it helps eliminate tungsten contamination. High frequency start is confused with High Frequency AC aluminum welding because transformer welders rely on High Frequency to start the arc and to keep it stabilized while welding. This is because a transformer switches so slowly that the arc itself will go out as the wave form goes through the zero point.

In an inverter this isn’t a problem as the switching is nearly instantaneous by comparison and HF isn’t used unless it is to establish the arc. Usually this takes less than a second. It can be used to weld in DC mode as well, and is a nice and preferred feature to have for both AC and DC modes if it is available. HF however, relies on a switch or foot pedal to activate the high frequency. For off the bench, in the field type work, it is not commonly used.