Following on from a post on another thread, I am having problems welding aluminium with my tig set.

I am a pretty handy welder on steel and stainless, but am struggling with ally, and I think I must be doing some thing fairly fundamentally wrong!

Obviously I am using AC and permanent HF.

Each time I try, I can't seem to create a properly oxide-free puddle, then, when I try to dip the rod, the radiated heat melts the end of the rod before I can get it near to the puddle, balling the end of the rod up and blowing it away from the puddle area.

I end up with a slightly sooty cratered mess to be honest.

I'm not 100% sure that the alloys I am trying are weldable, that could be one issue, but I have tried on several pieces of different types with similar poor results!

I might not be using enough gas, do I need a lot more than with stainless??

What I really don't understand is why the rod keeps melting before I get near the puddle, no matter how quickly I try to move it!

what am I doing wrong????

any tips greatly appreciated!!

[Edited on 16/11/06 by NS Dev]

Oxide free puddle?
Are you using the right gas and have you got enough flow?
You must use almost pure argon for aluminium.
As to the rod melting back, most problems are to do with the angle of the torch when you introduce it.
Trying to weld cast aluminium, contamination from oil or the welding of maizac will cause dirty welds.
Maizac is an aluminium zinc alloy which is brilliant for fine castings but is unweldable as the maizac disintergrates faster than you can weld.

[Edited on 16/11/2006 by nitram38]

quote:

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Originally posted by nitram38
Oxide free puddle?
Are you using the right gas and have you got enough flow?
You must use almost pure argon for aluminium.
As to the rod melting back, most problems are to do with the angle of the torch when you introduce it.
Trying to weld cast aluminium, contamination from oil or the welding of maizac will cause dirty welds.
Maizac is an aluminium zinc alloy which is brilliant for fine castings but is unweldable as the maizac disintergrates faster than you can weld.

[Edited on 16/11/2006 by nitram38]

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Your gas flow should be about half way on the gauge and the torch can be tilted slightly.
Also try your welds on known aluminium to make sure that what you are welding isn't the cause of the sooting problems.

Also, is your tungsten rounded or pointed?
It should be rounded for ali and pointed for steel.

Other than that, feed the rod FASTER!!!!



[Edited on 16/11/2006 by nitram38]

yep torch needs to be nearly vertical as the arc tends to get blown about by the gas flow. a larger gas shroud may also help. if you are right handed with the torch you need to be welding right to left with a slight angle in the direction of welding, also try to move the torch back to the right of your pool then introduce the rod then move the torch back over to the left of the pool.

There's a bit here that has something sounding like your problem Nat. I only tig welded steel and it was years ago so I can't comment on how right he is but it says for beginners so he may have some helpful comments.

no matter how good you can tig steel ,ally is another matter .i can get bywith ally but as soon as i strike i back right off the power with the pedal as the same thing happened to me with the rod dissapearing before it touches the job. i can stick two pieces together but havent managed to make any thing pretty yet i have a mate who is superb with ally and he put me right but i cant seem to get consistent results no matter what i do

Also if I remember rightly, zirconium tungsten tip for ally and ceriated tungsten for steel.

Dave

One or two pointers that may help when TIG welding aluminium
The rod should be approximately the same diam as the thickness of the material to be welded and of a similar composition.
Up to 14swg use 10 cubic ft/hour flow argon flow. Increase this flow slightly if material is thicker.
Use Ceriated tungsten electrode which is suitable for both aluminium and steel.
Electrode should have a rounded end and before welding, condition the tip by setting to maximum and striking the arc on a block of thick copper or aluminium etc. This should produce a hemisphere on the end of the rod.
Aluminium is super sensitive to the distance of the rod from the job, idealy about 3mm. A much greater gap will cause oxidation.
You should aim for an angle of 90 degrees between the torch and the rod.
Typical welding currents
18 swg 60-70 Amps
16 swg 70-90
14 swg 90-110
Post gas is very important so set this to at least 7 seconds.
Make sure the aluminium is actually melting before you dab in the rod. Be prepared to burn a few holes until you can recognise when it is ready for the rod.
When butt welding aluminium, unlike steel there should be no gap. Tack every inch to ensure minimum distortion and maximum heat transfer. Use a higher current to tack so that you can go straight in and out.
I believe the Miller website is helpful and can I'm sure explain things much better than I have done.
http://www.millerwelds.com/education/library.html
Anyway, I hope you succeed but do please send a U2U if you have anything that you think I can help you with.

alb

John

thanks folks!

Hi.

I've been thinking about your problem and reading and rereading this thread.

There is much useful advice above and I don't want to contradict anyone,
but a thought or two on gas flow has crossed my mind.

Small gas shrouds, for a given flow rate, tend to create a jet of gas.
A larger shroud, with the same flow rate, gives a more gentle flow.

If the angle of the torch is too shallow a high gas velocity will draw air in from behind, so big is best.

Ally because of it's heat transfer rate produces a wide weld for it's thickness, plus the area that
the cathodic action cleans, make the size of area to be covered with the argon even bigger.

I wouldn't use anything smaller than a 12mm ceramic, and would use 10 l/min flow rate.
If your torch doesn't have a diffuser gauze then stainless wire wool inside the ceramic can help.

The ball end on the tungsten is important so turn the heat up and arc up on some scrap to form the ball.
Don't forget to turn the amps back down though.



Now for the arc.

Does your welder have a wave balance knob?
This can be called by other names, depending on manufacturer, but basically it sets
the percentage of time the electrode is positive or negative.
i.e. when it's cleaning and when it's heating.

My Miller is variable between 20 and 90% if I recall. My Lincoln at work is 1 to 10 and also has an auto balance setting.

You should be able to weld newish sheet ally with just a light degrease.
Grind, sand, or wire brush on old castings only.

I take it your tungsten is not protruding too far, just enough to be able to see it, and that the torch
is almost upright, and the arc gap is not too long, or too short.


Hope this helps

ATB

Paul G

Cheers Paul!

I need to sort my power supply out as with it being dark all the time I am at home now the trips are more than a nuisance!!

I have all the bits to wire it up nicely, just need some daylight!!

I'll try a bigger cup and gas lens, and keep the torch more vertical, I have tended to have it at quite an angle