Thin Anodized Aluminum?

[jeffscarstrucks]

I have some .040 anodized aluminum that I would like to repair a short crack in as well as a couple of small pieces that I would like to join in an outside corner type weld (fusion). I tried some different settings as I have read Hawk's posts on this before but really only had limited success. The machine is a Dynasty 200. I tried using 1/16 Lanthanated but didn't have a chance to sharpen up the .040 tung yet. I am looking for some specific settings if anyone has any ideas. I can do fine on standard Al but it is the anodizing I'm trying to get a handle on. The standard answer is to remove the coating but this is fairly cosmetic and visible and I have read about tecniques that allow a nearly weld-through process (next time I'll copy them!). Thanks, JEFF

[HAWK]

Jeff,

Have you tried just scratching enough anodized to get a good arc on the material? I have had pretty good luck starting the arc on bare metal and using 500PPS with 55% peak time and 30% background amperage settings. If you are running helium in your shielding gas, try cutting your peak time to 35% and background amperage to 25%. A higher arc frequency should help regardless of argon or argon/helium shielding.

I did some .0625" anodized material earlier this week with a 50/50 helium/argon mix using the settings above with 115 amps on the machine and 1/16" ceriated tungsten. The frequency was 250HZ and the foot pedal was about half way down. It ran hot and the bead was a little wide. However, ther results were much cleaner than with argon only. Just a thought.

[jeffscarstrucks]

Thanks Hawk, I'm going to get back to it this evening or tommorrow at the latest and will try your settings. I knew you had a considerable amount of experience with this and was hoping you would see this post. I remember a thread that dealt with welding through the coating on tubing in marine applications but I wasn't sure how it would apply to thin material. Thanks again, JEFF

[glockdoc]

With a squarewave machine I've used DC positive. Really good cleaning action. Best on really thin AL and requires big tungsten. Not sure if this will work with your machine though.

[ASKANDY]

Most of the anodized that I do is thicker than that but the method I use is a trigger spot at the set amperage. I push the trigger and quickly add filler, stop, move over slightly and trigger again. With your .040 on an outside corner, you'll have a tougher time.

A-

[HAWK]

Jeff,

Andy is right! You wil get less graying of the anodized coating by spotting. I mis- read the outside corner joint. The 250HZ arc is probably going to be too tight for this joint. Open up the arc by dialing down around 110-125HZ.

[jeffscarstrucks]

I wish I was writing with test results but instead I realized that I'm out of small pieces to experiment on. I have enough for the small items I have cut already and a full sheet on the wall. I can't bring myself to hack on a full sheet for practice so I'll wait until I can nab some scraps from a friend. I will report back as soon as I get back to this project. I have written all of these variables down and they are on the machine waiting for trial. Thanks as always for detailed answers and taking time to post! JEFF