Aluminum Welding: Aluminum is one of the most notoriously difficult metals to weld.
It has a reputation for being difficult and unforgiving and it's not an experience many people take to easily. However, there are some basic tips that can be kept in mind while one is learning aluminum welding. Try not to get frustrated, as even experienced welders experience many problems with their first tries on any aluminum projects.
The first thing that you must do when welding aluminum is to clean it first. Aluminum is much more finicky than steel in that regard, and cleaning it doesn't mean just wiping it off either. You have to clean it with a solvent of some kind first and then after that, rinse it, and then scrub it with a STAINLES steel brush. When scrubbing with the brush only scrub in one direction or you stand the chance of actually embedding impurities into the soft metal, which you defiantly don't want.
TIG welding works well for many people for the purposes of welding aluminum although different people prefer different methods. When TIG welding aluminum it works best to use only an argon gas or possibly an argon helium mix. If you're MIG welding you'll want to use argon as well. You also want to use equipment exclusive to aluminum welding. For example the steel brush should only be used on aluminum.
Here are two thoughts about heat and aluminum to keep in mind. You may want to use a heatsink to draw heat away from the metal. Heat travels very well through aluminum and once you get your weld area hot enough to weld that heat can travel through the rest of the sheet to the extent of causing warping if you're not using some kind of a heatsink. Also, think about preheating your aluminum before welding. This is a subject with a little bit of "heated" debate going on, but especially if you're welding thicker pieces of aluminum you will find preheating to give you an easier time of it than not.
Follow the usual rule of using the same kind of rod as base metal that you're working with and use aluminum while welding aluminum. The final tip for aluminum welding is to weld hot and fast. If you take too much time while welding aluminum you can end up burning holes right through your material very easily.
There are some basic pointers to keep in mind while welding aluminum. It is a difficult metal to work with, but because of its flexibility and lightness if you can master the working of it you will be a much more versatile metal worker in the long run.