This Time It's Personal: Welding training at Delta's TechOps Center raises the bar

This Time It's Personal Welding training at Delta's TechOps Center raises the bar By Mike Sammons When it comes to welding , Delta Air Lines Technical Operations Center (TOC) at Atlanta's Hartsfield International Airport performs...

By controlling the initial volume of current, this machine offers "soft start," "standard start," or "hot start" arc starting conditions. Soft start helps operators working with small diameter tungstens or thin metals, while hot start improves starts with the larger diameter tungstens used for welding thicker material.

"It doesn't take much to blow through the .012-inch honeycomb skin of an exhaust sleeve," notes Scott Morris, TOC welder. "Before we had the new welding power source, we had problems welding at lower amperage. Now that we have the Syncrowave 250 DX, we have better control, better arc starts, and [we] don't fight problems with weld quality. Another thing I love about this machine is its Fan-On-Demand®. The cooling fan only runs when needed. This shop is quieter than most, and Fan-On-Demand lets us play our radio or talk. Before this we sometimes put in ear plugs."

Like all Syncrowave machines, the new machine's squarewave balance control permits tailoring the arc for more cleaning action to remove heavy oxide layers or more penetration on thicker aluminum and magnesium. Miller Electric introduced the Syncrowave welding machine with its squarewave AC output technology. Squarewave technology minimized the problems inherent with AC welding on aluminum and magnesium: arc stumbling, wandering, and outages.

Welding power sources with a sine wave output typically experience problems during the Electrode Negative (EN) to Electrode Positive (EP) transition of the AC sine wave. Sometimes, these older units 1) did not have enough "push" to drive the arc through the zero amp range and then re-establish the arc at the electrode or 2) they could not transition through the zero amp range quickly enough.

If five or six EN to EP cycles fail in a row, the welding output begins to resemble DC. If this occurs, a TIG machine reaches for open circuit voltage in an attempt to get enough voltage to re-establish AC welding output. Unfortunately, the excess voltage can cause current overshoots (voltage spikes). During the EP to EN half cycle this may produce tungsten migration, which degrades weld quality.

Squarewave technology shortened the switching time between EN and EP, so it created a more desirable arc. So desirable, in fact, that all higher-end AC TIG machines now feature squarewave technology (Miller's patent expired in 1994). Instead of a sloping sinusoidal wave, a squarewave makes a nearly vertical transition between EN and EP. This greatly increased arc stability, improved arc starts, and reduced arc wandering.

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