Aluminium TIG help

[Phataz1]

Hi everyone, after putting up a thread recently asking for help with welding up a stainless inlet manifold, and finding all the advice a massive help, I thought I would do the same with the aluminium one I am attempting. It has another 10mm flange in place of the metal gasket underneath the tubes which isn't in the picture;

Basically I am just finding it difficult to create a weld pool on both the surfaces to be joined, and the filler rod just wicks and drops off no matter the angle. I got the gaps between the surfaces mega tight as I know this is supposed to help. The runner tubes are 2mm thick and the manifold flanges are 10mm. I am using a 2.4mm tungsten and 4043 filler at 120 amps on AC. AC balance is around 50%.

After having similar problems with stainless and being advised to shorten my arc length to around 1-2mm (which helped), I thought it must be the same solution with aluminium. But the closer I got all it seemed to do was draw any filler material towards it like a magnet, so I end up touching down and contaminating the tungsten. What sort of arc length should I try to keep?

The other problem I was encountering is the filler wicking before it reaches the weld pool. I have seen plenty of tutorials on ali TIG and they all say that the angle of approach should be 90degrees to the torch, but this just would not work for me. The only way I found it to wick less was when I directed it in at around 45-60 degrees to the torch?! What angle should I aim for?

I have actually completed the welding on it and I will get some pics up to show how it turned out Some of the welds came out really neat, but the majority of them were a blobby mess. Hopefully someone will be able to offer me some advice.

Thanks,

Arun

 

[derekm]

...Basically I am just finding it difficult to create a weld pool on both the surfaces to be joined, and the filler rod just wicks and drops off no matter the angle. I got the gaps between the surfaces mega tight as I know this is supposed to help. The runner tubes are 2mm thick and the manifold flanges are 10mm. I am using a 2.4mm tungsten and 4043 filler at 120 amps on AC. AC balance is around 50%.

...
The other problem I was encountering is the filler wicking before it reaches the weld pool. I have seen plenty of tutorials on ali TIG and they all say that the angle of approach should be 90degrees to the torch, but this just would not work for me. The only way I found it to wick less was when I directed it in at around 45-60 degrees to the torch?! What angle should I aim for?

...,

Arun

120amps doesnt sound enough to do 10mm

Are you moving the torch away from the pool back along the weld as you dip the rod in?

 

[Drains]

Aye, current's low - should be more like 200 (or more) for 10mm. Also you need to allow for the aluminium sucking the heat away from the weld. Either be patient, or pre-heat the job.
Don't bother dipping the filler until there's a weldpool to dip into. You can leave the filler in the gas shield, but away from the arc until it's dip time. As I say, be patient and wait for the pool to form. If you have a footpedal, whack up the amps to speed it up, then back off to welding current when the pool forms.

 

[hotrodder]

Rtech 161 right? If so i'm afraid nowhere near powerful enough for that job really, at least with the parts set up for a fillet weld. Lots of preheat on the 10mm flanges may get it done

If you make the inlet runners so they pass through the gasket flanges (stopping short of the gasket face) making the welds a sort of outside corner come lap weld set up the amperage requirements will be a lot lower. Obviously need to consider what may be required match porting wise though...

Arc length is really related to amperage and tungsten size, typical rule of thumb is no longer than the tungsten diameter i.e. higher amperages = bigger tungsten and bigger weld = slightly longer arc length if that makes sense.

Biasing the AC balance towards %EN will put more heat into the weld. This came up recently with the Rtech manuals contradicting themselves regarding the effect of AC balance, IIRC it works backwards to normal and turning it down (towards 30) results in more workpiece heating and less 'cleaning' action.

Found the thread discussing Rtech balance settings

 

[Rick]

I weld 10mm inlet flanges at about 200 amps, obviously depending on how "big" the actual flange is, but I move pretty quick and back off on the pedal once started.

If you preheat you might get away with 140 amps but anything less you'll struggle.

 

[Freshfabrications]

As per Hotrodders info on arc length bigger tungsten = bigger arc length but also the fact that it's not the tungsten dia but in fact the ball dia on the end of the tungsten iapwYs run quite a bit longer arc length on AC than on DC if I was using 2 mm on DC I'd be at 4mm on AC and that's from the weld reinforcement.

One trick if your lacking the amps to get good penetration is: be patient, as sugested above, and use what is called the welders weave or whip technique.

This is to melt in a pool and advance forwards and melt it longer then back trackand add filler it's inportantthat it's a slow ish back and forward movement along the seam, always bias the heat to the thicker material, and add medium amounts of filler after each whip movement and it builds up nice little ripples too.

In essence you are preheating a good few milimeters in advance of where your about to add filler and thus not just heating and cooling as with normal step pause fill step technique....

Hope this makes sense!?!

Good luck

 

[derekm]

Rtech 161 right? ...

If you make the inlet runners so they pass through the gasket flanges (stopping short of the gasket face) making the welds a sort of outside corner come lap weld set up the amperage requirements will be a lot lower. Obviously need to consider what may be required match porting wise though...
...

A variation on this :
bore the flange from both sides so that the runners stop on a 2mm wide 2mm deep lip in the middle of thickness of the flange. Then weld on the inside.

With this techniqure see if you can use 6mm flanges as you may have much less distortion as the heat is in the middle of the flange and not concentrated on one face

 

[Phataz1]

Ahh I see, thanks for the info guys. I made the daft assumption that the amperage would be the same for the same material thickness, whatever the material


I think the method of having the tubes pass through the flanges is one I will start to use from now on, it seems like a much better way of doing it. Will just have to adjust the flange CAD files to suit.

Hotrodder, yes the AC balance information I read in the R-tech manual confused me as the results I found when playing around with it seemed to show the opposite of what it said...

Appreciate all the help and advice everyone Thanks very much.

I will give the ideas a go and report back

 

[derekm]

And you would be better with a 3.2mm tungsten if you are really winding the amps up.

just been messing around with some 6mm ally and changing to 3.2mm tungsten
from 2.4mmis quite dramatic. but thats on a 200 amp set.

 

[heinz57]

If it's more penetration from a smaller machine you want then you could try a Helium/Argon gas mix, although I know the helium is expensive. Just a thought
mate, best of luck.

 

[Phataz1]

Cheers for the advice everyone, I just thought I'd bump the thread to show you that I managed to weld the manifold up OK. Wasn't neat lol, but I welded it inside and out and it held together fine. filed away most of the un-neatness and here it is fitted;

I'm really warming to aluminium as a material, apart from the welding which I find more difficult than steel, its really nice and easy to shape and looks really nice and bright!