Most people assume that TIG welding anodized aluminum is just like welding any other aluminum piping. That is absolutely wrong and one of the big secrets that very few welders know. Anodized aluminum requires bumping or spot welding! Yeah, that the big secret!
In order to get this type of pipe welded you need to do two passes. The first pass is spot welded all of the way around with the filler wire being added. On the second pass you spot weld all the way around but without the filler wire added this time. The reason for this is anodized aluminum has a very hard coating that is difficult to melt through. The first pass will join the two pieces together but not melt the anodized coating into the weld area thoroughly. Since the coating is not melted properly the weld will look very rough. The second pass is used to melt the anodized coating into the weld better and give the weld its smooth appearance. Finally the weld is painted with weld paint. This is done because the anodized coating will no longer completely cover the weld area, so weld paint must finish the job to protect the weld area.
TIG welding anodized aluminum requires three things:
- First is an A/C and D/C TIG welder with a high frequency start button on the TIG torch.
- Second is a pure tungsten electrode with a tapered ball shaped end.
- Aluminum weld paint,
To prepare the tungsten to weld anodized aluminum you need a tapered ball shaped end. To do this you simply put the tungsten into the TIG torch. Next turn on your welder and set it to D/C electrode (+) positive. Finally hit the high frequency start button and strike an arc on a piece of clean steel or ideally pure copper. Once the arc starts keep turning up the amperage until the tungsten starts to melt. Finally when there is a tapered ball end, stop the arc. That’s it!
The actual welding is done by spot welding all the way around the pipe. The first thing you will need to do is set the TIG welder to A/C alternating current. Typically there will be two passes needed to weld the pipe. The first is with the filler wire added and the second it to smooth out the weld. The trick to TIG welding anodized aluminum is to keep your amperage on the high range and the spot welds should typically last about one second in time each.
Once the welding is finished all you need to do is paint the welds. That’s all there is to TIG welding anodized aluminum! Once you get going with this type of welding procedure you will be amazed how good the welds look on anodized aluminum piping!