TIG Welding super thin stainless steel?

[Andy Wilson]

Hi there,anybody got any thoughts on welding super thin stainless steel? I have been tasked with welding damaged aircraft exhausts with a very thin,0.010" and less, blanket over a heat barrier welded to the exhaust duct. It is literally like welding a thin foil patch to a thin foil jacket! Luckily my Fronius magic wave can turn right down but any advice would be appreciated,thanks.

 

[BrokenBiker]

move quick and don't hesitate. 10 thou should require 10 amps using the rule of thumb but if you can i would be inclined to go lower, although my inverter claims to have a 5 amp start but im not too sure it actually is 5 amps.

 

[daleyd]

Surely you need.............

http://www.mig-welding.co.uk/forum/...or-at-least-that-is-what-i-think-it-is.44202/

 

[Andy Wilson]

Thanks guys,think going to pass on that £1700! Cheap and cheerful welder,made that mistake before and that's why have a Fronius now! I practiced on a waste exhaust and the margins are very tight! By the time it is enough of an arc to weld, it has blown through! Any thoughts on adding Helium to the mix?

 

[Paul.]

Helium will only make things hotter, I'm not sure that manual tig is your answer here, perhaps plasma arc may be suitable, doesn't aircraft work have to be carried out by a certified welder working to a wps ?.
I once made some helicopter exhausts, wheeled up from flat sheet in 2 halves but the customer wouldn't let me weld them, they went off to a specialist company to be welded.

 

[hotrodder]

Helium will make it hotter as said. Pulse is your friend for stupidly thin stuff... at high frequencies it constricts and stiffens the arc improving focus and stabilty. Still no margin for error but a bit more forgiving than constant current. Undoubtadly a lot easier than what you're trying, probably part geometry more than the fact it was a tad thicker at 14 thou but FWIW... http://www.mig-welding.co.uk/forum/threads/cross-eyed-fun-stoopidly-thin-stuff.27937/

What dia filler wire and tungsten are you using? Personally i don't bother with tungstens smaller than 1.6mm but when the welding gets silly thin i pay more attention to the prep, sharpening them with a longer taper and much finer finish than i normally bother with

As Paul, i've had to pass on aircraft exhaust jobs before because i didn't have the relevant certs. That said CardiffRob (member here) has something like 'firewall forward' exemptions under the LAA which apparently provides more freedom

 

[toddy]

at my work we are having to work with 0.0010" or 0.25mm s/s

and it is great fun at least.. we currently use about 10a from a miller maxstar (found to have the best low end current rating)
and a 1mm tungsten at about 6ipm (inches per min)

 

[Freshfabrications]

Just incase its not patently obvious, and or hasn't been said, make sure things are clean and purge the inside or back of the weld. Not done tones of 0.5mm but I know from the tubes I weld for bike frames (0.6mm) that dirty can get your weld out of shape pretty quickly.

 

[Jim Davey]

I just sold an EWM Plasma 20 set, (20 amps at max power) goes down to fractions of an amp with a tig torch but even more controllable with the plasma torch fitted. About 5 grand as a tig only package, closer to 7 grand with a plasma torch, water cooler and the two multistage regs required for the gas mixer panel. Would do your exhausts no problem though.

 

[Eddiegrease]

Sounds like Great project! Like was stated you will need to be clean and use low amps with a backing purge...if no backing purge is possible use copper backing clamped tight... Liquid flux can be used also...good luck

 

[Andy Wilson]

Hi there guys,thanks for the help. Exhausts were for Eastern Europe helicopters and I am licensed and authorised to certify them. I used the pulsed mode at a high frequency on my Fronius MW 2000. I used a purging dam made from insulating putty and it worked well. I cut open a scrap exhaust after practice welding and it was only very slightly discoloured, so points to good weld. Current was 5 A and I used some multi strike tungstens from Huntingdon Fusion Techniques. I ground them on diamond wheel to a long point, approx 8D. Very happy with results and exhausts back in service with happy owner.
Anybody else tried these tungstens? I really like them and impressed at excellent tip duration. They don't exactly specify dopants they weld like 2% lanthanated .

 

[hotrodder]

I switched to 'em several years ago. They're a mixed flavour; lanthana, yttria and ceria IIRC

 

[whm_fab]

Hi there guys,thanks for the help. Exhausts were for Eastern Europe helicopters and I am licensed and authorised to certify them. I used the pulsed mode at a high frequency on my Fronius MW 2000. I used a purging dam made from insulating putty and it worked well. I cut open a scrap exhaust after practice welding and it was only very slightly discoloured, so points to good weld. Current was 5 A and I used some multi strike tungstens from Huntingdon Fusion Techniques. I ground them on diamond wheel to a long point, approx 8D. Very happy with results and exhausts back in service with happy owner.
Anybody else tried these tungstens? I really like them and impressed at excellent tip duration. They don't exactly specify dopants they weld like 2% lanthanated .

this sounds nice, get us some pics Andy!

 

[lshigham]

Hi there guys,thanks for the help. Exhausts were for Eastern Europe helicopters and I am licensed and authorised to certify them. I used the pulsed mode at a high frequency on my Fronius MW 2000. I used a purging dam made from insulating putty and it worked well. I cut open a scrap exhaust after practice welding and it was only very slightly discoloured, so points to good weld. Current was 5 A and I used some multi strike tungstens from Huntingdon Fusion Techniques. I ground them on diamond wheel to a long point, approx 8D. Very happy with results and exhausts back in service with happy owner.
Anybody else tried these tungstens? I really like them and impressed at excellent tip duration. They don't exactly specify dopants they weld like 2% lanthanated .

I use them too. Expensive, but nice to use

 

[HughF]

Good job for the old boc micro plasma I have sitting in the shed, never used it! 20 amps maximum

 

[cardiffrob]

That said CardiffRob (member here) has something like 'firewall forward' exemptions under the LAA which apparently provides more freedom

Ahh, that was just for the one airframe for which no plans existed and everything had to be "Do what you think is best".