Aluminum firmly entered into human life. Every year its consumption only increases. In industry and the household, there are many products from this metal. To create new or repair old items for various purposes, an aluminum electrode is used in the welding process. How to use it correctly, you should understand before carrying out the work.
Aluminum properties
To understand how to use an electrode for aluminum welding, one should understand the inherent qualities of this metal.
The surface of aluminum during oxidation in air is covered with an oxide film. It is quite difficult to melt. Also, aluminum welding with an electrode should occur in a special gas environment. Otherwise, molten droplets of the substance in the air will become oxidized and will not merge into a single substance. In this case, a seam cannot be created.
For welding aluminum with a tungsten electrode, argon or its more expensive mixture with helium is used.
Despite the fact that aluminum is a faster molten metal compared to steel, it requires 1.2 times more welding current to process it.
Electrode welding principle
To understand how to cook aluminum with an electrode, you need to understand the essence of this process. There are two main varieties of it. The first uses a tungsten electrode when welding using inert gases. It is called AC TIG.
The second method is the use of coated melting electrodes without the use of inert gases.
In both of these cases, the general principle is the need to melt the oxide film. For this, alternating or direct current of reverse polarity is used. This leads to cathodic destruction of the film. Another type of current, an aluminum electrode will not be able to perform its functions.
Coated Electrode Welding
Welding of structures with a metal thickness of 4 mm or more is carried out using piece coated electrodes. This mode is called MMA.
This type of welding gives a low quality of the seam, a sufficiently large spatter of metal and poor removal of solidified slag. The latter provokes the formation of corrosion.
An aluminum electrode of modern grades allows welding almost all aluminum alloys. The process occurs using direct current having the opposite polarity.
In order for the quality of the weld to be within normal limits, you should first warm up. For a workpiece of medium thickness, it is 300 degrees, and for a thick one - 400 degrees. Heating and gradual cooling ensure good penetration of the metal and avoid the formation of crystallization cracks.
Welding occurs continuously using a single electrode. They should not do lateral vibrations, as with steel.
Tungsten Welding
The previous option, due to insufficient quality, is rarely used by professionals. Today, craftsmen use such a variety of work as welding aluminum with a tungsten electrode in an inert gas environment.
This method is used for designs that have high demands. A tungsten electrode provides seams with maximum strength and aesthetics.
When welding is used, argon or helium is used to protect the surface of aluminum from oxidation. The arc is supplied with alternating current. This allows you to qualitatively break the film on the metal.
The torch is moved behind the filler wire, and not in front of it. You should also consider a heat dissipation system. This is especially important for thin workpieces.
It should also be remembered that too high an inert gas flow will suck air into the arc region. Too little gas or too fast work will cause the aluminum surface to oxidize anyway. Argon must be started 5 seconds before arcing. After its break, the inert gas turns off after 7 seconds.
Having familiarized yourself with the welding technology that uses an aluminum electrode, you can carry out this process at home. However, before starting work it is better to practice a little on unnecessary workpiece. Then the seam will be smooth and strong.