|Oscar Kjellberg Founder of ESAB|
As early as 1903, Oscar Kyellberg, founder of the ESAB welding machine company,created a heavy-flux welding rod to create an envelope of shielding gas around the welding point. In the absence of shielding gas, molten metal tends to oxidize rapidly,causing problems such as brittleness and other weld defects. A large advance was made in the World War II era – again, pioneered by ESAB – when shielding gas was fed directly through the nozzle from a separate tank, allowing welding machines to be made which removed the need for flux coating – and the slag and dross it leaves behind on the workpiece surface.
The initial shielding gas used in ESAB welders was helium, giving the first machine to use this type of gas feed the name of “Heliarc,” after “helium” and “arc.” It was soon discovered that other gases, such as argon, were cheaper and equally effective, however,so helium was relegated to a role as a gas to be mixed into the argon when special welding needs were being met.
Today, various gases are used depending on the type of material being welded.The closest thing to an argon welding machine is a TIG welder with an alternating current option to be used on aluminum. The main model of ESAB TIG welder is still called the Heliarc, even though it now mostly uses argon, or argon slightly diluted with helium, as its shielding gas.
Argon Welding with TIG
Any welding machine that uses a separate gas supply for the shielding gas (rather than a flux-coated electrode rod, as in stick welders) is a candidate for functioning as an argon welding machine. A MIG welder can potentially be used with 100% argon shielding gas. However, since MIG welders are used frequently for ferrous metal welding, being less suited to welding aluminum or magnesium, the usual shielding gas employed for this welding is carbon dioxide (CO2) or a combination of CO2 and argon, since pure argon causes erratic arc performance when welding steel.
TIG welding machines, on the other hand, almost always use argon, either in its pure form or combined with helium (and occasionally other gases), as the shielding gas. Pure argon is the choice for very thin pieces of metal, with helium added once the pieces reach a certain thickness, and more helium added as thickness increases. Sometimes, the argon concentration will sink as low as 25% of the total, depending on the type of material, its thickness, and the depth of weld that is needed.
Read also : Amperage and Other TIG Welding Settings
Helium makes the weld penetration deeper, and is also useful for creating a higher welding pool heat with copper and aluminum, which tend to conduct heat away from the welding point rapidly. Helium also increases welding speed. The tradeoff is that the weld quality is significantly lower than is the case when argon alone is used, which can be a major problem if the weld will be subjected to heavy stress or pressure.
Argon welding machines provide an excellent weld when used with alternating current. The weld quality is high and the appearance of the weld is smooth and attractive as well. This method is best for aluminum and magnesium. Nickel and stainless steel are welded with a mix of argon and a whiff of hydrogen – the latter gas is used in higher concentrations for copper, but cannot be used for aluminum, magnesium, or stainless steel because of the chance of damaging the metal and the weld.
Argon welding machines are typically best used with the push method of welding, where the torch or welding gun is pointed forward towards the welding pool. This is exactly contrary to the pull welding method used most of the time with carbon dioxide welding.
Welding with argon is a skilled, but highly flexible, task that can be used to bond all types of nonferrous metals and is especially useful when alternating current is the power source. Together, these factors make a strong, high-quality weld with a stable arc, and are especially suitable for aluminum and magnesium – two of the most demanding metals to weld.