tig welding aluminium

[hornet]

I bought a Kemppi ac/dc tig at an auction about a year ago, i already have a dc tig but wanted to weld aluminium, it came with a torch , and a box of assorted tugnstens. i could not get it to weld aluminium ,the two surfaces seemed to be repelled from each other. no matter how we set the controls it would not weld aluminium. we contacted our local kemppi agent and he insisted on taking the welder away , when the welder was returned they had changed the torch for another kemppi one but this one has a gas lens where the old torch only had a collet/sleeve and ceramic , when i use it for aluminium it works fine, is it possible to weld aluminium without a gas lens ?

 

[shenion]

I did it without a gas lens without much problems. A gas lens helps as you can reduce the gas flow and it won't cool the weld pool as much.

The two sides "repelling" each other is normal, nature of the beast. I always have to make sure it has a real tight fit between pieces or bridge with filler first.

 

[Paul.]

I do a fair bit of aluminium and rarely use a lens, did you ask them what problem they actually found, you may have had a leak or it could just have been a problem with the torch drawing in air, faulty or missing back cap seal is favorite for that.

 

[voipio]

As Shenion said, using filler rod will definitely help. 4043 has good flow characteristics.

 

[hornet]

they said the torch was leaking air , it worked fine for stainless but not for ally .when i remove the gas lens and fit the new torch with the same white tungsten/collet and holder it is just the same as the old torch . no matter what i do i cannot get it to join two pieces together . with a gas lens and using filler rod it will weld a bead on the surface like a tilted stack of coins but without the gas lens i cannot get the filler rod to take at all .

 

[hotrodder]

As said definatly do not need a gas lens to weld aluminium

Some torches require the use of a different or additional insulator (white ring between ceramic and torch body) with a gas lens. Could be the source of a leak, i've seen it before but the other way round i.e. someone adds a gas lens to a torch without changing the insulator and shielding quality goes to pot

Odd thing regarding the stainless though as it's sensitive to shielding quality- i would expect a leak bad enough to make welding Al impossible to at least result in dark, dirty welds with stainless

 

[Freshfabrications]

If the Aluminium your welding is dirty, or has a poor fit up it will not take well to just trying to melt the parent prices together, if they melt they shoul go mirror shiny and join, you should always use a filler to tack and weld where possible, unles it's a specially designed joint, aluminium is hot short ie cracks when hot so it's good to use filler to reinforce!!

If you could post a better discription, ie get tecnical for me an list all the settings, material, prep, flow rate etc etc then I can have a think for you.

My main tip for now is tight joint fit up, unless it needs a root gap on a but weld, file the edges/burs off, gently wire brush by hand with a new wire brush just for ally a centimeter or so all allong and arroind the joint, then wipe the whole joint down with acetone or IP1 alcahol and allow to evaporate before welding ( be fire safe )
then make sure you use about 50-70% ac + on your setting for ac ballance so it's lightly less hot but more cleaning, controll the arc so you melt both peices evenly and when the metal melts to super shiny posetively push in a good bit of clean filler then withdraw it compleatly from the pool, it should be tacked then!

Ally has to be super clean to weld nice as does your tungsten ceramic etc

any questions pm me

 

[hornet]

i have removed and refitted the collet holder , collet , white insulator rear cap & ceramic checking the fit for leaks and now when i try to weld alu it works fine without a lens . i still have to old kemppi torch ( it was not returned with the welder but when they sent me the invoice i questioned what happened to the old torch and they returned it ) i thought i would try again with the old one ,when it was returned it was missing collar cap collet/holder and ceramic , upon inspection of the torch someone has cut the rubber where the white collar fits so now the neck is scrap . i have a neck for a parweld 17 and have made an adaptor to fit it and it works fine with a lens and without.

thanks for your help .

 

[pedrobedro]

There are different insulators for different ceramics, check you have the right ones for the job or they will not seal up to the rubber torch body.