Thin anodized aluminum

By Paladin (***)

Date 02-04-2010 14:17

A while back I was asked if I would be interested in welding some anodized aluminum pans. At the time I did not ask what the thickness of the aluminum is. Turns out it is 0.035. I have asked but have not heard back what alloy the pans are broke up with.
Most of the aluminum welding I do is with a spool gun but do break out the TIG machine occasionally. The good news (I think) is that I have a Miller Dynasty 200 DX.

Any advice from you experienced Al TIG hands would be appreciated.

I did do a search on this forum but did not see anything on welding very thin anodized aluminum.

What size tungsten
What size and alloy filler?
AMPS?
Balance settings?
Frequency settings?
Use the Pulse feature or pulse with the foot pedal?

Any other advice (besides staying home sick Monday)?

Thanks.

By Lawrence (*****)

Date 02-04-2010 15:37

Paladin

First advice would be to remove the anodize coating prior to welding.

There are techniques for welding annodized aluminum, but in my opinion those techniques are pretty much limited to thick sections.

If you are doing pans a close fitup in the corners is a must. Both edges touching.. no gap with .035

a piece of angle, or a copper bar clamped flush to the inside can be used as a heat sink so that you can make a nice outside corner weld.

A 1/16th cerium, lanthanum or zirconium electrode would be best.. go ahead and put a blunted point on the tungsten.

Set your Dynasty to about 55% EN for balence control. Maybe set your current to 50 amps to start.. If pedal to the metal does not get you a nice bead than increase in 5 amp incraments. Frequency 200 Hz

If you are not seeing a nice etch at the toes of the weld than reduce EN in 5% incraments.

Remove the annodize with a 1 or 1 1/2" 80 or 120 grit silicon carbide disc in a pnumatic angle die grinder.

By aevald

Date 02-04-2010 15:51

Hello Paladin, as usual, Lawrence has included pretty much the complete package for being as successful as one might expect with the situation that you have described. I would only add considering the use of a SS angle, block, or other stainless steel backer, the tighter to the inside surfaces of the corner the better. You are certainly facing a challenge, anodizing will affect surface depth to varying degrees, .035 thickness doesn't leave a lot to work with so be as careful as possible with the dressing portion of your prep. You might also consider bending some lead in tabs to be clamped as close as possible to the start of the weld with the end of these angle tabs contacting the corner of the pan and starting your weld bead on them and then welding from the tab and then onto the corner of the pan this might prevent excessive burn-back on the start of the corner of the actual pan. Just a few more items for your consideration. Best regards, Allan

By Paladin (***)

Date 02-05-2010 03:47

Thanks for the advice. I will try those good ideas. I did get a sample piece to practice on. I too had assumed an outside corner joint. But the liaison for this job wants to fold the corner and weld the seam (a lap joint) on the inside. I'm not sure if this will be easier or harder. And he said it was 0.040 so I have another 0.005 to work with.
Thanks, Floyd.

By aevald

Date 02-05-2010 05:06

Hello Floyd, that might present some other challenges as you won't be able to clean the joint area where the top piece laps over the other surface. I don't envy you on this one. Good luck and best regards, Allan

By Paladin (***)

Date 02-11-2010 14:16

I was able to make the weld on a test piece. To tie in both edges I generally had to really stack up the weld. It did not look cosmetically good. So the contractor decided to calk the the joint instead. No big disappointment .
Thanks for the help. Lawrence your setting were right on and Allan the backing plate is a good idea.
Floyd.

By aevald

Date 02-11-2010 15:42

Well glad to hear that you got the issue resolved, don't think missing out on that particular task was necessarily a bad thing. Although, it certainly would have been a challenge, in both patience and ability. Best regards, Allan