[TIGolBiddies]

Hi, everyone. This is my first post on here and its great to see a community with so many experienced guys trying to help each other.

I've got some background with MIG on mild steel, mainly fabricating parts for turbocharged setups on cars and some art work. I'm just self-taught.

I always wanted to learn how to TIG, and a few months back found out that my company had a little Miller DC TIG unit that I've since been practicing on over my lunch hours. I've gotten to the point where I can get a decent bead on stainless, so I decided to give aluminum a shot.

I read some previous threads on DCEN and Al, and I think my main issue is failing to get the oxide off before welding. I'm running 100% argon, which I know is not optimal, but it's what I have available, so I'm trying to make it work.

Today, on my latest try, I used a new stainless steel wire brush wheel on an angle grinder to grind away material in an attempt to remove the oxide layer. The aluminum looked bright, but still wouldn't form a puddle like I'm used to with stainless. I used a larger cup (7) and upped the argon to 25-30 cfm, but still couldn't get a decent puddle going. These were all just autogenous passes on 1/8" stock.

Instead of pudding up, the metal would just darken and then eventually begin to melt away underneath the outer skin as the heat built up.

Can anyone offer any tips for getting a really basic setup like this to do crude work on aluminum? I'm not expecting it to be great, but I've seen some excellent results from far more experienced welders working with similar setups, so I feel like there may be something technique-oriented that I can fix to get some sort of improvement. Eventually, I plan on getting a proper AC rig but, in the meantime, it would be nice to have some ability to build with aluminum.

Thanks for any advice.

-Rob

[weldin mike 27]

Hey Mate,

Welcome to our forum, glad to have you here,

I havent tried to weld Al like that, but as you said, others here do it, I think it is used on thick stuff that uses high amps(?) It may require a change in polarity. Not sure, Good luck with your practice, someone with real experience will be along soon to help you out.

Mick

[Otto Nobedder]

I want to say DCEN aluminum requires at least a high-helium mix, if not a 2% hydrogen,

but I'm speaking out of turn.

There are a few here with experience who will speak up once they notice the topic.

Steve S

[StephanusThie]

I think this could help

http://forum.weldingtipsandtricks.com/v ... f=5&t=2002

Steve

[TIGolBiddies]

Thanks for the replies, Steve and Mick. That actually brings up a related question I've wondered about. What is it about some processes that make helium, argon, CO2, etc. the best choice for that operation and not others. Given the idea of a "shielding" gas as something to prevent oxidation, I can't figure out why argon, helium or another noble gas wouldn't always be a good choice, as they are the least reactive. Any thoughts or good references on the chemistry?

Thanks,
-Rob

[TIGolBiddies]

Steve, that's actually the thread I read that seemed to provide the most hope for this DC + argon idea. I suppose I'm just trying to dig out more specific advice, either on cleaning aluminum or using argon with a DC arc from people who have messed with it. I'm nut sure why the stainless wire wheel seems to fail at oxide removal. Maybe I'm using it wrong, I'm thinking.

Thanks,
-Rob

[zigeuner]

I recall that many years ago when I worked at Rocketdyne, there was some excellent welding being done on aluminum and stainless as well. This was before square wave and inverter technology was invented. The machines used were some of the big Aircos and other so-called Heli-arc machines. They used straight helium and lots of amperage on DCSP (DCEN). The welds were just superb. All welds were X-rayed and stamped by an inspector as to their integrity. There was no shortage of stacks of dimes on those welds, ether.

So, sure you can weld aluminum on a DC machine. The negatives are that helium is very expensive in comparison to Argon and it's also prone to leakage due to the small molecule. It also takes a lot of power to do it properly with helium, but yes, it can be done.

[robertnz63]

I have a small vintage japanese motorcycle repair shop with a lot of repairs bieng done to aluminum casings that are getting hard to replace so we tig them up. No shielding gas required just some coated aluminum rods (hobart OK, alumweld etc) and your machine set to DCEN. The flux reduces the concentration of heat and readily breaks down the oxide layer allowing full penetration welds. 80 amps is sufficient to weld up 1/8" casing but move fast after establishing the puddle it will not fall out as badly as shielding gas method (Heliarc). works great everytime im on to get the flux mixture from superiorflux because these rods are expensive (but well worth it). The next thing to do is build an xray machine this fall so i can examine the welds in detail. you will be very happy using this method for those smaller random jobs its cheap too my 3 in one chinese CT312 (120 amps)cost me 350 dollars. and puts casings together like a pro.!!
cheers Rob

[Cortesjoel]

Aluminum requires high frequency so it's used with AC polarity

[zank]

This video will get you going.

http://youtu.be/H_DwA0vzKXI