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TIG Welding Aluminum on DC

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TIG Welding Aluminum on DC

Postby RedIron881 » Wed May 09, 2012 9:23 am

I've gotten into this debate many times with younger welders right out of school all the way up to welders twice my age and experience. The debate about TIG welding Aluminum on DC. They all say you Can't do it! One thing I've learned in my 15 years in welding is there no such thing as Can't in this industry, you just don't know how. So, figured I'd post something about it and see what all you welders around the world have to say.

Here is the recipe I like to use...

Set machine for welding Steel no more than 190-210 amps regardless of thickness, need a foot pedal for this
Standard or gas lens set up (Gas lens is a bit cleaner but not needed)
2% tungsten works fine 3/32-1/8 sharpened
4043 rod 3/32 (depending on thickness of course)
25-30 psi of Helium (use the helium to bump up the heat not the amps)
5 psi Argon (helps clean up the weld a bit but also not always needed)

A few Pros and Cons

Pros...

-Don't have AC and need to weld aluminum!
-No Preheat for thick parts
-Makes for a great small root pass (preheats for the cap) or one large pass
-Burns much hotter so you can get in and out with minimum warpage but still getting good penetration

Cons...

-Dirty looking weld (until you figure out the right angles). If the material is dirty it really shows in the top and bottom of the weld (as in the photo) but comes right off with a wire brush. This was just handles for a base plate so didn't need to clean up nice.
-Wire will ball up very easy if not added properly. It's not forgiving so add it in the right spot
-Uses a lot of Helium which isn't cheap but if you're welding of a machined billet plate that can't warp too much...


Anyone else ever try this? If not give it a try.
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Re: TIG Welding Aluminum on DC

Postby CoreyMac » Wed May 09, 2012 11:08 am

I guess if you found a procedure that (gets you by) then more power to you. But you NEED AC to do a proper weld because one cycle digs and one CLEANS. If you take the cleaning cycle out the weld will be dirty (to say the least) and won't pass any inspections (if needed). If your just sticking 2 pieces of aluminum together fine but I'll stick to AC.

IMO
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Re: TIG Welding Aluminum on DC

Postby ajlskater1 » Wed May 09, 2012 1:35 pm

CoreyMac wrote:I guess if you found a procedure that (gets you by) then more power to you. But you NEED AC to do a proper weld because one cycle digs and one CLEANS. If you take the cleaning cycle out the weld will be dirty (to say the least) and won't pass any inspections (if needed). If your just sticking 2 pieces of aluminum together fine but I'll stick to AC.

IMO

ya i agree. I have done some welding aluminum on dc before as kinda of quick get by type of deal for a couple buddies when my syncowave broke down at the shop at the house a couple years ago. But I definetly would not want to do it on some critical and it also kinda took the fun out of welding aluminum for me because I was not able to get that nice stacked dimes look.
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Re: TIG Welding Aluminum on DC

Postby RedIron881 » Wed May 09, 2012 5:54 pm

IMO,

I have to disagree with you about passing inspections using DC. I have passed many NDT tests using this process (Penetrant and X-Ray), so it can do much more than just get you by. Yes, AC is preferred 98% of the time but just wanted to share with others looking for that 2%. When it is called out on the print it's handy to know how to do.
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Re: TIG Welding Aluminum on DC

Postby rahtreelimbs » Wed May 09, 2012 8:17 pm

You seemed to have proven your point to yourself. But I have to ask..............can you weld aluminum on AC ??? If so, why not stick to AC ???
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Re: TIG Welding Aluminum on DC

Postby RedIron881 » Thu May 10, 2012 8:48 am

rahtreelimbs wrote:You seemed to have proven your point to yourself. But I have to ask..............can you weld aluminum on AC ??? If so, why not stick to AC ???


Yes, I can weld aluminum on AC. I learned it just the same as everyone else that welds aluminum. Where DC comes in handy is in that photo the base plate has a vacuum sealing surface on the other side, so with DC you can get in and get out with very minimal warping. On AC with those thicknesses you have to linger around a lot longer putting more heat into the part which could warp the plate out of tolerance. Could you put the parts in a oven heating everything evenly, weld it on AC and let it cool to get less warping, absolutely. DC is just another option and in some cases with thicker parts a faster one. Which is why I wanted to share this Tip on the Tips and Tricks forum for other welders that might not have ever known how or tried it. Use it or not is solely up to the welder with the torch in their hand (and there employer...)
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Re: TIG Welding Aluminum on DC

Postby bryce39 » Sat Oct 06, 2012 11:38 am

Sorry, I had to register to comment on this. Yes, aluminum can be welded with DC and pass whatever tests given all day long! The preferred method is AC because people do not know what they are doing when it comes to aluminum DC plain and simple. If you brush the material with a stainless brush, clean with acetone, machine settings, torch angle, etc the weld will be just as pretty as AC and have deep penetration as well. The sooty layer will be present in the weld but very minimal, just lightly brush it off and you are good to go.
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Re: TIG Welding Aluminum on DC

Postby rahtreelimbs » Sat Oct 06, 2012 2:31 pm

bryce39 wrote:Sorry, I had to register to comment on this. Yes, aluminum can be welded with DC and pass whatever tests given all day long! The preferred method is AC because people do not know what they are doing when it comes to aluminum DC plain and simple. If you brush the material with a stainless brush, clean with acetone, machine settings, torch angle, etc the weld will be just as pretty as AC and have deep penetration as well. The sooty layer will be present in the weld but very minimal, just lightly brush it off and you are good to go.



I would really like to see some examples on DC welded aluminum !!!
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Re: TIG Welding Aluminum on DC

Postby bryce39 » Sat Oct 06, 2012 3:45 pm

If I can remember, I will take some pictures of welds on a 1/4 t joint and upload them. If everything is correct, people cannot tell the difference between DC and AC aluminum. I will take a picture of the weld before I brush it off so you know that I am not bullshitting you
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Re: TIG Welding Aluminum on DC

Postby Otto Nobedder » Sat Oct 06, 2012 4:07 pm

Bryce,

Don't be "sorry" that you had to register. All input is welcome here. I have no doubt on the DC Al. Though I've never had to do it myself, the logic is sound. The pre-clean is the key, as you don't have the electrode-positive phase to do that work for you.

I look forward to seeing the pictures, and since I love to learn new things, I may have a question or two for you and RedIron. I have a great deal of autonomy at work, so I can experiment with this there. There is an application that comes to mind where the penetration is more important than the appearance (as I assume, like most things, I won't master it in the first go :lol: )

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