How to Keep TIG Arc Inside Aluminum Lap Joint?

Welding Techniques, Theory, Machines and Questions.

Moderator: Harold_V

Post Reply
User avatar
SteveHGraham
Posts: 7788
Joined: Sat Jan 17, 2009 7:55 pm
Location: Florida

How to Keep TIG Arc Inside Aluminum Lap Joint?

Post by SteveHGraham »

Today I started welding aluminum. The speed of preparation allows me to devote a much bigger percentage of my time welding instead of grinding and cutting.

Question: when you're lap-welding 1/8" aluminum, is there a secret to getting the arc to stay in the joint? I was chasing it all over, and the welds were huge and crazy-looking. I increased the frequency from 75 Hz to 125, and it made things easier, but it was not the answer.

The welder was set at about 140 amps and 25% AC balance. I was using a 3/32" E3 tungsten.

Flat beads seem to be as easy as they are on steel, or maybe a little easier. The arc stays put. It seems like the big problem with aluminum is trying to keep up with the melting metal. It goes much faster than steel.
Every hard-fried egg began life sunny-side up.
User avatar
GlennW
Posts: 7284
Joined: Sun Apr 15, 2007 9:23 am
Location: Florida

Re: How to Keep TIG Arc Inside Aluminum Lap Joint?

Post by GlennW »

A pic might help.

You may be holding the electrode too far from the puddle.

Do you have the high frequency set on "continuous"? (I've never tried AC without it, so I don't know what it might do)

Is that 25% EN or 25% EP? In other words, is that 25% cleaning or 75% cleaning. Different machines can display it differently. (I'm not an inverter guy)

Dunno anything about E3. I've used pure , Ceriated, and Lanthanated.

Also, if you contaminate the tungsten the arc spreads out,(and changes color) so the puddle gets huge.
Glenn

Operating machines is perfectly safe......until you forget how dangerous it really is!
User avatar
SteveHGraham
Posts: 7788
Joined: Sat Jan 17, 2009 7:55 pm
Location: Florida

Re: How to Keep TIG Arc Inside Aluminum Lap Joint?

Post by SteveHGraham »

The high frequency is continuous. I don't actually know whether the 25% is positive or negative, but it was recommended for this welder, so it ought to be pretty close to right.
Every hard-fried egg began life sunny-side up.
J.Ramsey
Posts: 147
Joined: Wed Jul 25, 2007 12:19 pm
Location: S/E Kansas

Re: How to Keep TIG Arc Inside Aluminum Lap Joint?

Post by J.Ramsey »

:mrgreen:
Last edited by J.Ramsey on Sat Apr 29, 2017 9:31 pm, edited 1 time in total.
User avatar
GlennW
Posts: 7284
Joined: Sun Apr 15, 2007 9:23 am
Location: Florida

Re: How to Keep TIG Arc Inside Aluminum Lap Joint?

Post by GlennW »

SteveHGraham wrote: don't actually know whether the 25% is positive or negative, but it was recommended for this welder,
If that is the recommended setting it is displaying EP.
Last edited by GlennW on Sat Apr 29, 2017 10:09 pm, edited 1 time in total.
Glenn

Operating machines is perfectly safe......until you forget how dangerous it really is!
User avatar
10KPete
Posts: 440
Joined: Wed Sep 30, 2015 5:29 pm
Location: Nordland, WA, USA

Re: How to Keep TIG Arc Inside Aluminum Lap Joint?

Post by 10KPete »

Arc blow can be a problem with all welding but "open ended" AC on alum. it can be worse. Tight clamping of the joint and/or tacking and then welding toward the clamp/tack will really reduce arc blow. Start you weld no more than say 4 inches from the clamp/tack.

This assumes all else is good.

Pete
Just tryin'
dbstoo
Posts: 32
Joined: Sun Oct 05, 2014 11:45 pm

Re: How to Keep TIG Arc Inside Aluminum Lap Joint?

Post by dbstoo »

The clue may be in the phrase "The speed of preparation allows me to devote a much bigger percentage of my time welding instead of grinding and cutting. "

Aluminum develops a high resistance oxide very quickly. Standard prep is to clean it, then brush with a dedicated stainless brush, then clean it with acetone and then weld.

A real long taper on your electrode will tend to jump around more. A shorter taper will be more focused.

Dan
User avatar
10KPete
Posts: 440
Joined: Wed Sep 30, 2015 5:29 pm
Location: Nordland, WA, USA

Re: How to Keep TIG Arc Inside Aluminum Lap Joint?

Post by 10KPete »

I haven't used one of those new inverter supplies yet, but I doubt the basics have changed...

I/we always used pure tungsten for AC and at most just broke the sharp corners off the end with the grinder. The tungsten forms a nice ball on the end naturally with argon. Even with a few percent helium cracked in. This was true with the old equipment as well as the SyncroWave running square.

Pete
Just tryin'
Post Reply