Aluminium Welding Machine
Not every welding machine is suitable for every kind of metal.
Aluminum is one of the more difficult metals to weld because of its natural properties, and an aluminum welding machine is necessary to make consistently good welds on this substance.
Nearly any kind of welding machine can be used to make an occasional weld on aluminum, including small MIG welders, but stick welders with shielding gas supplied by a heavy flux coating on the electrode rod are completely ineffective.
The welding machine best suited to fusing aluminum is a TIG (tungsten inert gas) welder.
These devices are the aluminum welding machines par excellance, and if serious aluminum welding is being contemplated, then investment in a TIG machine is the essential first step.
TIG welding is especially suitable for welding the thinner weights of aluminum, and since this metal often appears in thin sheets for various applications, the welding machine is likely to handle most welding tasks involving aluminum that general users are likely to encounter.
TIG welders of all sizes exist which are capable of welding aluminum. Small, portable TIG welders that are carried with a shoulder strap or even a suitcase-like handle can be used for aluminum welding as much as their larger, more immovable counterparts.
Most modern TIG welders can switch between direct current and alternating current. Alternating current (AC) is the one most suitable for aluminum welding, and current technology built into TIG welders keeps AC welding arcs very stable for a clean, effective weld.
Special considerations in welding aluminum
Aluminum can be a difficult substance to weld because of its unusual characteristics. One of the largest obstacles to successful aluminum welding is when the metal is not cleaned properly before the weld is made.
Aluminum develops a “skin” of aluminum oxide on its surface very rapidly, and if this skin is not removed immediately before welding, various unexpected and unpleasant events can follow.
The oxide skin has a melting point of 3,200 degrees Fahrenheit – far above that of the aluminum itself, with its melting point of 1,200 degrees Fahrenheit. This skin can therefore deflect an incautiously-directed welding arc, resulting in an erratic or feeble weld. Aluminum has a lower boiling point than its own oxide coating, so it is also remotely possible to heat the aluminum inside its skin until it sprays out as a liquid.
Fortunately, it is possible to clean the oxide layer off aluminum before welding.
This should be done no earlier than eight hours prior to the actual welding, and should be done even closer to the welding time if possible.
A strong alkaline solution should be used for the initial cleaning, followed up with water washing.
Nitric acid should then be used for a second cleaning, with another water rinse after that, and thorough drying before welding. If a brush is used, the bristles should be stainless steel, and the brush should be used in one direction only.
If the oxide layer is especially tenacious, then filing or grinding can also be applied to clean and prepare the surface – a drastic but effective measure.
Contaminated filler wire is another source of weld weakness when welding aluminum. The wire used as filler in the weld pool should be high quality aluminum welding wire, manufactured to prevent contamination, and carefully stored up to the point when it is actually used.
Other issues affect aluminum welding machine performance as well, but cleanliness of the aluminum surface and the filler wire are two of the most important things to consider when preparing for aluminum welding.
Aluminum Welding Machine
Of all the materials that the welder is likely to come into contact with regularly, aluminum has the most unusual welding characteristics, and requires special handling to some degree to produce a solid, effective weld.
An aluminum welding machine is a regular MIG or TIG welder being used with these special requirements in mind, and with its settings adjusted to meet the needs of the aluminum welding process.
Even stick welding machines and gas torches can be used to weld aluminum if the proper precautions are taken, although this requires both skill and perhaps a bit of luck as well.
Preparing the aluminum for welding
Regardless of what kind of aluminum welding machine is used, the aluminum must be prepared for the weld by thoroughly cleaning the surfaces that are going to be welded.
Aluminum does oxidize slightly, and this creates a layer of aluminum oxide on the surface of the metal which cannot be seen with the naked eye.
However, this layer has a melting point three times higher than that of the aluminum beneath it, and, as a result, it will cause erratic welding arc performance.
The aluminum oxide will shield the aluminum to a degree, and this can result in weak welds.
To clean the aluminum for the aluminum welding machine, the welding surfaces should be washed with acetone. Brake cleaning fluid should not be used for cleaning, as it can make poisonous fumes when vaporized by the arc welding machine.
Washing the welding surface with water and a stainless steel brush after using the acetone will complete the process of preparing it for welding.
The weld must be completed within eight hours of this cleaning; if it is not, then the welding surface must be cleaned again in exactly the same manner.
MIG aluminum welding
The best aluminum welding machine in the MIG (metal inert gas) style is one that can handle higher voltages and higher amperages than are typically used for steel. If thick aluminum is going to be welded, then at least 200 amperes is required.
A continuous voltage machine is the best choice for aluminum welding, because the ability to fine-tune the voltage will make it easier to find the proper level for the specific workpiece that is being welded, but a cheaper tapped-control welder can also be used if that is what is available – as long as the user can accept slightly less perfect welds.
The shielding gas that should be used with MIG welding of aluminum is pure argon. Under no circumstances should CO2 be used as shielding gas, since this will cause rapid oxidation just as oxygen does with regular steel.
Ordinary gas hoses can be used for argon, although CO2 regulators will need to be switched out if they are installed on the machine.
The wire electrode needs to be carefully chosen as well, since aluminum welding requires special wire of a specific size.
Soft aluminum alloy gives the best weld, and 0.035” wire is practically the only diameter that will function properly with a regular MIG welding machine, as thinner wire will not feed properly and thicker wire will not be melted by the typical MIG arc.
Adding an aluminum feeder kit to the machine will greatly assist in using the MIG as an aluminum welding machine – the contact tips are particularly important, since these will have a larger hole, and aluminum expands to a greater degree than steel when it heats.
The wire spool’s loose end must be held firmly until it is locked between the rollers, because any unraveling of the aluminum wire spool will completely destroy any chance of using that particular spool successfully.
The aluminum should also be preheated to a maximum of 230 degrees Fahrenheit, or the welder will be risking weld cracking. Aluminum welding must be carried out using the push method, as any other method is likely to allow oxidation to occur.
TIG aluminum welding
Many of the same considerations that apply to using a MIG device as an aluminum welding machine also apply to TIG welding of aluminum. The aluminum should be cleaned in the same fashion, using acetone followed by water and a stainless steel brush. Preheating is also necessary.
TIG welding machines do have a number of special considerations when welding aluminum, however – some of these positive advantages over the MIG method, and some less advantageous.
On the plus side, many TIG machines offer an alternating current (AC) setting, which is excellent for welding aluminum because it provides a more stable arc with this metal.
High amperage is still necessary, and water cooling is helpful to the process. (A copper heat sink should probably be attached to the aluminum parts as well, to prevent warping from heat escaping from the welding area.)
TIG welding machines can also use harder aluminum alloy feeder wires than MIG machines can, meaning that there will be less feeding problems during welding.
Argon or an argon/helium mix are both acceptable as shielding gas with a TIG aluminum welding machine.
On the downside, the tungsten electrode of a TIG welder may become contaminated while welding aluminum and need to have its tip snapped off to clear the contamination.
The pieces must also be fitted more snugly than is the case with more rough-and-ready MIG welding – the TIG weld will be of higher quality, but narrower than the MIG weld, so good fitting is essential.
Regardless of the exact type of welder that is available, it can be adapted to function as an aluminum welding machine by taking a few simple steps and precautions.
MIG and TIG welders alike can be used to conquer and fuse this difficult substance and create good, lasting welds.
Argon Welding Machine
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.
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.