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New to Aluminium Tig, no penetration

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New to Aluminium Tig, no penetration

Postby musccoo » Mon Feb 12, 2018 5:17 am

Hi guys,

I am self taught, just like doing my own and friends projects in the garage. Have got reasonably ok at mild and stainless steel tig, so thought I'd try give alloy a go.

Firstly, machine settings, Boc Smoothcraft 185 hf:
3/32 tungsten, White band (Zirconiated)
1/16 filler 5356
AC balance pretty neutral about 50%
Pure argon gas
Gas lens #8

Aluminium, not sure what type, about 2mm thick, I clean it with acetone before welding.

So practiced on some flat plate, varying with amperages, think I got it going ok and ended up on about 58amps (top middle ones)

Image

Then trying on some intercooler pipe I had lying around was an absolute disaster. Same settings and as soon as I get the puddle going it caves in.

So I keep trying turning the amps down about 5 at a time, I end up on 30amps and its still doing it. I can stuff the filler in and just try save it but its not right. Then the penetration looks messed from the other side, I doesn't even look like its penetrated, I'm really confused.

I can't even get a nice bead going.

Any help MUCH appreciated!

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Re: New to Aluminium Tig, no penetration

Postby cj737 » Mon Feb 12, 2018 11:28 pm

Change the balance up to 70%, 50% is actually creating too much penetration.

In your two pictures of the interior of the tubing, the large “warts” is the penetration soaking through due to excessive heat and balance. Aluminum once hot, holds it heat. So get your puddle, then add filler and taper off your amperage with your pedal.your material is pretty thin, so it will be difficult to weld if you keep practicing on the same piece without allowing a significant cooling time. Or quench it with a water bucket as you practice.
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Re: New to Aluminium Tig, no penetration

Postby Arno » Tue Feb 13, 2018 3:06 am

cj737 wrote:In your two pictures of the interior of the tubing, the large “warts” is the penetration soaking through due to excessive heat and balance.


Yup.. Also keep in mind that the oxide 'skin' on alu remains intact on the back side so unlike steel(s) the back won't really want to 'fuse' into a single weld but tends to stay 2 pieces. That's what usually happens.

Jody has this video where he shows the back of an alu pipe as he's welding on the front and you can see the way the back remains 'covered' by the oxide layer (around 1:38):

https://www.youtube.com/watch?v=XzsfBV6_vNY

I guess to get a smooth fused weld on the inside too you'd need to progress to a gapped style setup where the filler basically bridges the gap between the material ends and that way creates the new inner surface.

Bye, Arno.
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Re: New to Aluminium Tig, no penetration

Postby musccoo » Tue Feb 13, 2018 4:46 am

Change the balance up to 70%, 50% is actually creating too much penetration.


Ohh right, ok that makes sense. I don't have a pedal at the moment was thinking I might get away without while I learn a bit.
So that would be why its caving in too fast...too hot and too much penetration..

Ill try change the balance, but do my amps sound about right?

Jody has this video where he shows the back of an alu pipe as he's welding on the front and you can see the way the back remains 'covered' by the oxide layer (around 1:38):

https://www.youtube.com/watch?v=XzsfBV6_vNY


Thanks his vids are great, I was looking for one like this but couldn't find it cheers!
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Re: New to Aluminium Tig, no penetration

Postby tweake » Tue Feb 13, 2018 5:17 am

musccoo wrote:Firstly, machine settings, Boc Smootharc 185 hf:

hows the welder?
i see they are on special at the mo, looking at getting one myself. btw pedals are on special to.
tweak it until it breaks
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Re: New to Aluminium Tig, no penetration

Postby Bill Beauregard » Tue Feb 13, 2018 8:26 am

You are using far too low a current. Aluminum conducts heat FAST. The bubbling on the backside is because you had to wait around too long to get a puddle to flow. Turning up the heat, then moving faster will improve that.

Willie
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Re: New to Aluminium Tig, no penetration

Postby cj737 » Tue Feb 13, 2018 8:35 am

To expand on Bill's point...

Since you are not using a pedal, and you are welding thin aluminum with thin filler, ONLY filler rod can control your heat while you weld. That means, once you get a puddle, you need to rapidly jam filler in to prevent melting the base material and getting blow-outs or burn-throughs. This is pretty challenging for a new welder.

Each time you add filler, the filler material cools the puddle to a small degree. With aluminum, the base gets hotter very quickly which is why a pedal or switch to control your amperage while you weld is very common. So you have that challenge. Then, you are relying on small filler wire which will barely cool your weld, another challenge. Until you get a pedal or switch, upsize your filler on tubing. You can still "dab" only a smaller amount (or more) and then you travel a bit quicker to control your heat-soak and prevent burn-through. Make any sense?

And welding tubing is very hard in steel, really hard with ally, and near impossible with thin ally, no pedal, and a new-to-welding welder. So you got all that going for you! :) Grab some slightly thicker material, up your amps, work in flat positions for more time to get your technique right, then work on vertical UP, edge welding, and then when you get a pedal, attack some larger tubing. Your results will be vastly different. ;)
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Re: New to Aluminium Tig, no penetration

Postby Bill Beauregard » Tue Feb 13, 2018 9:07 am

Lets use the analogy of an ice cube. Ice is liquid or solid at the same temperature; 32F. Yet the transition from solid to liquid in either direction involves 746 BTU per pound. Latent Heat Of Fusion. Dropping in Ice, even at 32 degrees will chill your drink. It won't freeze it because heat transfer slows as ice, and drink equalize in temp.

A puddle of aluminum will immediately transfer heat to filler rod. As aluminum is super efficient at conducting heat throughout the piece, the back of the weld solidifies as fast as new filler liquifies. The stack of dimes appearance comes from the rapid freezing of each puddled bit of filler. Usually stepping up a size in filler, is very beneficial. I use 3/32 filler even on very thin aluminum sheet.

When we make a fillerless weld, no chilling ice cube effect happens. Aluminum is very fragile in this not quite solid, not quite liquid state. Dipping filler, melting it, draws the heat away from the very near part where we no longer want it wet. It is no longer as weak.

Willie
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Re: New to Aluminium Tig, no penetration

Postby noddybrian » Tue Feb 13, 2018 3:07 pm

In pictures that model though basic appears to have slope down so it's still possible to get away without a pedal hitting the initial amps hard then using the downslope as a kinda pulse.
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Re: New to Aluminium Tig, no penetration

Postby musccoo » Tue Feb 13, 2018 3:19 pm

Wow thanks for all the suggestions, this forum is really helpful.

hows the welder?
i see they are on special at the mo, looking at getting one myself. btw pedals are on special to.


Yeah seems pretty good for a 'cheapy', I have an issue with the pulse not working but warranty will cover that when I can be bothered, everything else seems pretty good for the money. I might just go get the pedal lots of people recommending it

You are using far too low a current. Aluminum conducts heat FAST. The bubbling on the backside is because you had to wait around too long to get a puddle to flow. Turning up the heat, then moving faster will improve that.

Willie


Right that makes sense, I realise Alloy needs a lot more current than the equivalent thickness steel, what would be about the right current on this size? 100?

Each time you add filler, the filler material cools the puddle to a small degree. With aluminum, the base gets hotter very quickly which is why a pedal or switch to control your amperage while you weld is very common. So you have that challenge. Then, you are relying on small filler wire which will barely cool your weld, another challenge. Until you get a pedal or switch, upsize your filler on tubing. You can still "dab" only a smaller amount (or more) and then you travel a bit quicker to control your heat-soak and prevent burn-through. Make any sense?


Yeah that does make a lot of sense thanks!

In pictures that model though basic appears to have slope down so it's still possible to get away without a pedal hitting the initial amps hard then using the downslope as a kinda pulse.


It's only got down slope for end of the weld not the start. I might just go get the pedal haha
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