TIG or GTAW (Gas-Tungsten Arc Welding) is widely regarded as the best method for finer welding of metals like aluminium. The welds are some of the finest, and with skill, may not even need any grinding. It also allows a welder to work with metals like aluminium, expanding their repertoire. In return, TIG does require you to learn additional skills, the primary ones being handling the filler rod with your free hand and potentially learning to control the output current with a pedal. The pedal control can be done away with in some cases where the welder provides some form of advanced automatic control. This gives you the opportunity to weld while standing up, something that is quite hard to do when controlling a foot pedal.
TIG welders come in many shapes and sizes, and the sheer variety is mind boggling. For instance, not all TIG welders have the AC functionality. However, to make the most of your TIG welding skills on aluminium, an AC/DC welder is a must. It allows you to weld metals like aluminium and magnesium. While small strips of such metals can be welded with just DC, they lack strength and will break under load. The high temperatures required for welding these metals with DC may also cause injuries or will damage your equipment.
AC/DC dual functionality is clearly the way to go, but there are some caveats to using such a TIG welder. The three most important ones are mentioned here.
• Rectification: At normal AC frequencies, the arc produced is unstable. As the AC cycle switches polarity, the arc may fail completely. High-quality AC/DC TIG welders avoid this problem by proving high-frequency output, square wave output, or both. The idea is to change the polarity extremely fast or switch it without causing a dip in the output current, which happens naturally in a regular sine wave AC output.
• Arc Start Options: The arc can be triggered by physically touching the electrode to the metal or with a remote start option. Remote starts use a high-voltage and high-frequency current to initiate the arc before they return to set values. This can be done with a torch that has a switch or a foot pedal trigger. The primary advantage is ensuring a clean work surface and control over accidental arcs.
• AC Output Control Features: These are features that determine how good an AC/DC TIG welder is. To put it simply, the ability to control the wave pattern of the AC output, as well as variable voltage and amperage adds a lot of versatility to how and what you can weld.
These features do not come cheap and high-end AC/DC TIG welders can cost almost five times as much as just a DC TIG welder. However, the options and features that such AC/DC TIG welders offer make the investment worthwhile.