Work on thin aluminum with the TIG method (GTAW)
Most welders are trained to master the gas tungsten arc welding (GTAW, better known as the TIG process) process by first joining pieces of carbon steel and then working towards aluminum samples, usually 3mm thick. They soon learn that aluminum, with its low melting temperature, higher thermal conductivity, and lower tolerances to surface contaminants, poses different challenges than welding steel.
When the job requires welding thin aluminum, starting at 1.5mm or less, welding is much more difficult. It's just not going to be as forgiving as when working with a thicker sheet.
Fortunately, the necessary motor skills learned in TIG moderately thick aluminum sheets are also applicable to welding on thinner material. It's just a different kind of welding that, like everything else, takes practice. These tips can help ease the transition for welders working with thin aluminum for the first time.
Take appropriate security measures
The fume extraction steps that most metal fabrication shops take to remove welding fumes and meet minimum safety requirements will work for the TIG method. The TIG process produces fewer fumes than other open arc processes, including gas metal arc, shielded metal arc, and flux-cored arc welding.
On the surface, that seems like a huge benefit to the welder because the shop can efficiently be meeting the guidelines and requirements, but the lower level of fumes means that the ultraviolet (UV) rays that result from the arc welding process are much more. Due to that and the fact that there is no slag system, the ultraviolet light emanating from the TIG process is more intense than with other welding processes at the same amperage level.
Because sparks and spatter are minimized with TIG, the temptation is to weld without protecting your skin from burns from molten metal. However, welders should be aware of the risk of failing to protect exposed skin from the UV light emitted during the welding process. Long-term burns and skin damage, similar to those associated with sunburn, can occur if the welder does not take precautions to cover exposed skin.
Welders need to select the correct shade on the masks for the process and current level used. Because the arc associated with TIG is very bright, a welder needs a darker shade than he might need for another welding process at the same current level.
Shade selection guides and other important safety information can be accessed free of charge by downloading ANSI Z49.1, available from the American Welding Society site (www.aws.org) or the websites of major manufacturers of welding equipment.
Adjust font values without fear
The DC power source used for the TIG process also works well for the electrode welding (SMAW) process, making it a multi-process machine. Welders often use welding power sources designed for the SMAW process to do some TIG jobs. When welding aluminum, and especially thin aluminum, it is essential to have a machine designed for the job. Aluminum welding is usually done with alternating current and some remote control type that allows the welder to adjust the current while welding, sometimes well below 10 amperes for some material.
When welding thin aluminum, the rule of thumb is to use about 1 ampere of current for every 0.025mm. The thickness of the material; that means around 50 amps for 1.25mm aluminum. This rule of thumb is just a guideline and is governed by many other factors, such as arc length, feed rate, joint configuration, and the amount of surrounding metal available to dissipate heat. Given this process variability, the welder will need to see the puddle and adjust as necessary.