Among the various welding methods, none can produce results that are finer than those obtained by TIG welding. It is little wonder that TIG (or Tungsten Inert Gas) welding has been the mainstay of aerospace fabrication, construction and repair.
TIG uses a non-consumable tungsten electrode to create the arc between the torch and the workpiece. The result is a smooth and refined finish. TIG also has the added advantage of being an excellent choice for welding metals like aluminium.
When welding Aluminium and other similar metals, they form an oxide layer when subjected to high heat. In order to break through the oxide layer, an AC current is required. Without going into specifics, the AC cycle allows the welder to alternate between penetration and cleaning the weld. The best TIG welders are AC/DC machines that are often more expensive than just DC TIG machines. AC Balance is a key feature that is prized by professional and hobbyists who work with aluminium or even thin steel and iron sheets. AC balance allows the user to control the AC output polarity ratio. In simpler terms, it allows control over how long an electrode stays positive or negative. Thus, a user is able to control the weld by balancing the penetration and cleaning cycle.
However, using AC also leads to the problem of rectification. Rectification causes the arc to break as the electrode switches polarities as a normal consequence of the AC cycle. This effect can be negated by using an AC/DC welder capable of providing a square wave output. High-frequency AC can also solve the problem. The best AC/DC TIG welders have both options.
People often find it hard to switch from welding iron and steels to aluminium. It is important to first practice with aluminium sheets and blocks. The results may vary, but the idea is to learn, not create a masterpiece. Eventually, you will learn to adapt and weld any kind of metal.
The only thing that remains is to acquire an AC/DC TIG welder. While a few welding supply stores in larger cities stock them, they are far from common. The extra cost often means inventory lies stagnant. The best bet is to opt for an online welding supplier. Buying online opens up the market where you have access to more brands and models. You can compare prices and features before choosing one that suits all your needs.