How to Keep TIG Arc Inside Aluminum Lap Joint?

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SteveHGraham
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How to Keep TIG Arc Inside Aluminum Lap Joint?

Post by SteveHGraham » Sat Apr 29, 2017 4:55 pm

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

Post by GlennW » Sat Apr 29, 2017 6:10 pm

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

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

Post by SteveHGraham » Sat Apr 29, 2017 6:52 pm

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

Post by J.Ramsey » Sat Apr 29, 2017 8:49 pm

:mrgreen:
Last edited by J.Ramsey on Sat Apr 29, 2017 9:31 pm, edited 1 time in total.

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

Post by GlennW » Sat Apr 29, 2017 9:20 pm

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

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10KPete
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Re: How to Keep TIG Arc Inside Aluminum Lap Joint?

Post by 10KPete » Sat Apr 29, 2017 9:34 pm

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

Post by dbstoo » Sat Apr 29, 2017 11:07 pm

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

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10KPete
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Re: How to Keep TIG Arc Inside Aluminum Lap Joint?

Post by 10KPete » Sat Apr 29, 2017 11:35 pm

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
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