TIG Anguish :( Can't Fillet or Lap weld Aluminium

[spudboy]

Anyone here a TIG welder, and does aluminium?

See attached photos for the mess I am making! Photos are basically the same, just one with a flash and one without.

I can run a reasonable bead with a filler rod on flat sheet, and can join with a butt weld 2 pieces, but as soon as I try and do a Lap Weld or a Fillet Joint it all falls apart.

My basic setup is an AC/DC Kemppi 230A unit, no foot control, air-cooled torch, running pure Argon, and "White tipped" 1% Zr tungstens (sharpened slightly to a blunt cone, not a fine sharp tip).

I am experimenting on Aluminium checker plate, just under 3mm thick. Am brushing it with a stainless steel wire brush - which is not used for anything else except aluminium brushing.

I seem to be "eating" the top sheet. I have tried numerous combinations of:
- Amps - around 80 but as low as 40 and up to 140
- Stickout distance of the tungsten
- a new tungsten
- putting the gas flow from 6LPM up to 8LPM
- going from a #6 shroud to a #8 shroud (made it worse)
- Fiddling with the AC mix, and injecting a bit of DC time
- Pulsing the AC
- Adjusting the AC frequency (between 60 to 120, even a bit at 200Hz, but mainly around 100Hz)

I seem to have contamination, often when I try introducing the filler rod. It starts spitting at me and gets the nasty blueish flame edges.

Anything anyone can suggest most welcome, as I am ready to go back to MIG welding steel and forgetting aluminium (well, that's how I feel tonight.....)

Cheers
David

[bblaze]

All the tigging Ive done has been stainless so no clue really. Could it be creating an air gap between the overlap so your top plate is getting to temp but the lower plate is way to cold. Why do you need to overlap, can you engineer to do fillets as like you say your flat plate welds look ok
cheers
blaze

[spudboy]

Well - my test welds are with the two flat sides of the chequer plate together, so not much of an air gap (at least not as much as there would be if the plates were around the other way....). However, they are just sitting on top of each other with gravity - do you think clamping them tightly together might help?

The torch is 80% focused on the base sheet so that's where most of the heat'd be going I reckon. Torch angle would be 10 degrees off verticle (looking from the front - pointing in the direction of the weld) and 20 degrees angled back "into" the join.

[John W]

It has been 25 yrs since my tig time but the edge of the overlap top plate does not have the heat dissipation that the base plate will have and as it is relatively thin at 3mm and presumably with air gap checker plate minimal contact with the base plate, so I would have started with a bead on the base plate and then run the bead up to the top plate edge with the arc flame largely on the bead.

[spudboy]

That is basically how I am doing it. I can get a nice shiny puddle on the base sheet, but I can't get the top sheet to "wick" together into the bottom sheet puddle.

It's like dealing with "reverse mercury". The two pools of molten ali do not want to join up and become one :mad:

[John W]

As said it has been a long time but we did have a white paste that was a flux for aluminium. Only remember using it for a couple of small jobs I did with an acetylene torch but cant think why it would not work with TIG. You are trying to do a challenging weld. The difference in heat sink with the 2 plate and a low tolerance between just right and a puddle not easy.

[Slunnie]

I've got no idea with the Kemppi as ours is an ESAB, also I'm not much into TIG work.

We turn the AC balance of the phases right down to the lowest base level and don't play with it - this stuffs the welds and burns the tungsten if you run too much heat into the tip.

We don't run DC at all with Aluminium - it doesn't allow the TIG to penetrate the Al oxide layer. Run DC when you are TIGing steel.

The high frequency is to start the arc without striking the tip and contaminating it, and so with AC current used for Al it needs to stay on all of the time as the current cycles.

You also need to sharpen to a tip with the grind pattern running down to the tip (ie not around) to prevent the gas from swirling on the tip.

Without being there, I would have also thought that you'd be running somewhere around 40amp to start at least - it just sounds hot, and you may also try to get more filler into it.

As I said, I'm not into TIG so others may have better info.

[spudboy]

We don't run DC at all with Aluminium - it doesn't allow the TIG to penetrate the Al oxide layer. Run DC when you are TIGing steel.



Thanks Slunnie - The DC thing when welding Al is called "Mix" mode. It mostly runs AC, but for a short period (maybe 20%) it goes to DC to get more penetration, then flicks straight back to AC mode. It happens so fast you can't see it, you just hear a slightly difference tone when welding.

[Slunnie]

Thanks Slunnie - The DC thing when welding Al is called "Mix" mode. It mostly runs AC, but for a short period (maybe 20%) it goes to DC to get more penetration, then flicks straight back to AC mode. It happens so fast you can't see it, you just hear a slightly difference tone when welding.
Ah thanks for this. Our machine doesn't have that. This is more than just altering the time balance between the AC phases by the sounds of it.

[NomadicD3]

Ho Spudboy, i too have taken on tig welding in my garage and had similar problem, all solved with the following
- clean ally with white sprit and wire brush as per uour doing
- use the correcdt type of filler rod 5356 is great for structural ally ie:6xxx or 7xxx series or for 5xxxx series 4043 or 5356 will do fine but 4043 has better weld properties.
- gas flow should be 10-12 ltrs/min, no higher
-frequency at 100-120 is good
Do youy have AC balance? It controls the percentage of time that the electrode is postive and negative. more time positive = more heat input more time negative = more cleaning effect on the material. Start at about 50% then as you get better go with more pos.
Now all that said and just guessing really i'd say that you need to start with attaining your molten pool on the main piece of material then wash across to the edge of the other piece, but once you have your molten pool on the main piece add some filler wire then wash to other piece of material edge.
Mate i have no idea if this will help but it's what i do and i've been getting some really good welds. That said for the first few days i was where you are.
Keep at it it's worth the effort!!!!!:)

[awabbit6]

... Now all that said and just guessing really i'd say that you need to start with attaining your molten pool on the main piece of material then wash across to the edge of the other piece, but once you have your molten pool on the main piece add some filler wire then wash to other piece of material edge.
Mate i have no idea if this will help but it's what i do and i've been getting some really good welds. That said for the first few days i was where you are.
Keep at it it's worth the effort!!!!!:)

I'd go along with this method too. Let the filler wire melt to bridge between your pool on the base material and the top piece. As you form your main pool, watch the piece on top as it will heat quickly (as you've found) and alter the torch position and angle to control it. Once the bridge is formed, use a combination of torch position and the addition of filler wire to help control the heat.

If you need to you could try clamping a heavy piece of steel across the top of the job about 1" behind the area to be welded and running the length of the weld. This will act as a heat sink and reduce the likelihood of the top piece pooling away from the edge.

I've done similar welds when I constructed my ally boat loader for the roof of my Disco. I really didn't find these welds too difficult - probably had a lot to do with the hours of practice I did on scrap to get a feel for the machine.

My TIG has no fancy settings. The AC is a straight 50-50 balance at 60Hz - no option to change. I think this worked in my favour as I had nothing to fiddle with except my technique.

Lots of practice ...

[spudboy]

I have gone through a whole bottle of Argon practicing :eek: Wonder how much that will be to refill....

NomadicD3 - if you are nomadding past Adelaide call in and give me a quick lesson. I will pay you in beer or wine!

It is only my first tank of Argon, so guess I will just have to put in some more torch time. I did have a bit more success, and managed about 3 or 4 sections which joined nicely, and just when I thought I had it sussed, I lost my mojo and it all turned nasty again.

Am going to take my sample welds into BOC tomorrow when I get more gas and ask them to show me how it's done. They sold me the Kemppi, so hopefully they might give me a few pointers.

Thanks for all the advice and words of encouragement. Will keep at it, as when you get one right it is a pretty good feeling :eek:

[spudboy]

- use the correcdt type of filler rod 5356 is great for structural ally ie:6xxx or 7xxx series or for 5xxxx series 4043 or 5356 will do fine but 4043 has better weld properties.


How do I tell what type of Aluminium I am welding? It is just some Chequer plate I got to practice on from the local scrap yard. Looks mint, so it is not dirty at all. I am however not cleaning it with white spirits or acetone. Is that important?

How do I find out what "series" the chequer plate I'm using is, and therefore what rods I should use?

BOC sold me a 2Kg pack of 5356 as they said this was the most common one to use.

[spudboy]

Got some Ceriated (sp?) tungstens and a bigger pink gas shroud (up 1 size) today, so will be out in the shed later tonight trying that out.

Bloke at the welding shop suggested 7L/M gas probably wasn't high enough, so will try at 9 or 10.

[NomadicD3]

Hi Spud, If only i had read your post last week B4 i drove back from melbourne to perth:(.
I just checked and i'm reasonably confident that all ally chqer plate is 5052 h34 but not 100% on that. Won't matter 5356 filler should work fine.
Stick with the zirconated tips best for ally. ceriated is more for ferrous metals.
Gas should definately be about 10ltrs/ min particularily on fillets where the gas can vent through the gap in the materials.It's been a few years since i was tig welding in a workshop{ ex sheet metal wkr} and the machines have changed alot with the invertor technology but gas flow and filler rods are still the same.
And funnyily enough i'm looking at my last gas bottle bill for a refill from boc , it's $156 for an E size bottle.
Not sure i can help much beyond that spud. Looking at your photos your speed looks good. Hey go to utube and do a search for tig welding tips i think there is a welding tips and tricks guy on there somewhere.
Good luck mate keep at it :D.
Nomad or not mad u choose LOL

[spudboy]

Ah bugger - that was bad timing :D

Actually - I just read the invoice from today and it was not Ceriated they sold me - it was Thoriated (ones with orange ends) so I think they are OK for AC work. MIG is quite a bit simpler - that's for sure.

I think you may be onto something with the gap between the plates. I can see that the gas might be escaping through the gap instead of flowing over the metal, so that is something else to change.

[NomadicD3]

Hey spud, my memory's not so clear these days but i'm almost certain you want zirconated tips, the ones with the white tips and make sure they the good quality ones, there are some chinese ones that have a kind of off white tip on them and they are sh#*...:mad:, learnt from recent experience:mad:
Also i assume you are using 2.4 mm tips?
3mm ally can be welded with 1.6 mm tips but is alot easier with the 2.4.
True mig is alot easier but i did alot of reading about ally welding before i decided to take it up again and the effect of the true purity of the weld has incredible impact on the strength of the final product and looks heaps prettier LOL.
I'm about to start building an almost completely aluminium TRUE offroad trailer and have spent many hours researching relevant information over the past 8 months and without question mig welding would take half the time to build but sacrafice way to much weld purity for my liking.
Cheers mate

[spudboy]

Well.... the different tungstens seem to have made no difference at all. Am still destroying perfectly good aluminium sheets at a prodigious rate :p

Have put the argon flow up to 10LPM but can't see any difference.

It's 1:15AM, so time to give up for another day and think about it again tomorrow.

[roverrescue]

Ummm,
not a GTAW proponent (I think for 3mm Al you should just reach for the glue gun!!! MIG)
but anyways when you say "a whole bottle of Ar" tell me thats not like a D or E size bottle because if it is that seems way thirsty for dialing in practise - unless there are sheets and sheets of practise run we havent seen yet!!!!.

Is it possible your reg is playing up and your flowing too much gas causing turbulence and poor shielding? My understanding is turbulence is an even bigger issue with GTAW than SMAW?

Ive had a regulator go bad - never dropped or damaged. Three D size bottles of Ar through it and on the 4th the second stage just let go, gauge stopped working and would almost free flow. If you have a spare reg may be worth trying?

Steve

[spudboy]

The bottle size is sort of navel height. Just fits in across the back of a Disco. Not sure what letter it is.

It has done quite a bit of steel TIG welding prior, so shouldn't really blame the Al welding solely for using it all up, but yes, I have done a lot of practice and wasted a lot of gas and filler rod :(

I have got a roll of Al wire and a new teflon 'sheath' for my MIG to try on Al, but not got around to testing that yet. I thought TIG would be neater and more controlled so was trying that first.

I did a dumb thing for 15 minutes last night, before I worked it out. I moved the welder on to the bench so I could change the controls more easily, and it was doing very bad welds full of contamination until I realised the cooling fans in the welder were blowing straight across where I was welding. TIG without Gas (or at least when you're blowing away your gas) is very nasty :p

[roverrescue]

If I had the machine I would certainly sort out Al TIG... as you say once dialled in you will have much better control. MIGing 3mm you gotta be quick on the gun, hot ally flows quicker than water!

Have you played around on <weldingweb.com> maybe do a search before getting flamed but plenty of pro welders on that board. They seem a little anti MIG for Al and are always recommending spool guns and what not (bad for me!) but in regards to TIG Im sure they will give you some leads on your dramas.

Steve

[spudboy]

That's a good welding website - just spent an hour reading articles on TIG, so thanks for that link.

[JohnF]

I started to do Aluminium TIG welding at TAFE [Techbnical College] on a Kempi welder. My son is an aprentice welder and learned TIG at TAFE on a Kempi.

Aluminium oxidises on the surface and that has a higher melting point that the aluminium just under the surface.

Perhaps their is a local TAFE where you can learn to TIG weld aluminium. It is worth while Ib believe, and the best way to go with aluminium.

Spudboy, my dad grew up in the Adlaide Hills [Mount Barker], and I lived there for a a couple of years fifty years ago.

[awabbit6]

I have gone through a whole bottle of Argon practicing :eek: Wonder how much that will be to refill....

That's about what I used to get my eye in. It takes hours of practice and lots of scrap.

I found that while I fiddled with the machine, I wasn't improving. I set everything to where I thought it was pretty right and then concentrated on my technique - that's when I began having success.

I also use 2.4mm Zirconiated tungstens for 3mm aluminium with 2.4mm filler wire. You can get away with a 1.6mm tungsten if your machine allows you to set the AC phase balance. If you set it to more penetration (more electrode negative time) the smaller electrode won't over heat and ball up too much.
I found I had better success with a bigger shroud (#6 or 7 I think - will check tomorrow). I can't remember the gas flow rate (because I don't touch it anymore) but I think it is set to 9L/min.

I also found this a very good resource for understanding the technical side of the TIG process.
Miller - Resources - TIG Handbook (http://www.millerwelds.com/resources/TIGhandbook/)

And this video was good to illustrate the correct technique.
YouTube - Tig Welding Aluminum - How to Tig Weld Aluminum - Aluminum Tig Welding Beads


and practice, practice, practice ....

[spudboy]

Just a quick follow up to this.

I got a new bottle of Argon, and hey presto - altogether different welding. I can now do nice shiny 'proper' welds that don't spit and erode half my sheets.

BOC (where I bought the Kemppi welder from) have been beyond brilliant. The regional sales rep visited my farm and took a look at the welder in situ to see if they could see what the issue was. Soon as we put on the new bottle of gas it was like a different machine. They are going to credit me for the dud bottle, which is very nice of them.

The bloke was there for over an hour and explained settings etc and got me to do some welds while he watched my technique.

So - high praise for BOC and now I can get started on my project :D

[NomadicD3]

That's awesome news Spud , great to hear and as i'm sure you have already found out, a good ally weld looks as sexy as hell by comparison to a ally mig weld. Good luck with your project. Sadly i have had to delay mine til for a few months however it to is a ally project so keep us updated and we can compare notes.
Bad gas was something that i would never have considered either in fact as far as argon goes it's the only time i have ever heard of it!!!!
Happy welding mate