Need Help...Welding Thin Sheet-Foil...Stainless...

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I need to weld very thin sheet or foil...about 0.1 mm to 0.3 mm...in stainless T-347...can this be done with a tig welder...?Regards,Gordon.
Reply:I welded something about 0,3-0,5mm, you need to clamp the sheet on a thick copper plate and use the wire from a stainless brush for filler, smallest tungsten you have , I had 1,6mm must sharpen it good and start the arc on the copper plate, a bit more gas then usual won't hurt. 5Amps.If it's 0.1mm don't bother , it's micro tig territory.--------------------------------------------------------------www.becmotors.nlyup, I quit welding.. joined welder anonymous
Reply:Thanks for the info...Glad to hear someone has welded that thin material...I would prefer to go thinner than 0.3mm but will settle for that if I have to...Clamping a very thick copper heat sink bar is not going to work...due to space constraints I can only get a 2.5 mm thick piece in there...The idea is to join two thin sheets arranged parallel to each other with a gap of about 2.5 mm between them...I was thinking of putting the copper strip in between and then laying a 2.5mm wire in the gap and resting on the copper...and then welding the thing shut...I was looking at the specs on some Miller machines and some of them claim down to 0.1 mm...these have high speed pulse up to 500 ppm...Not sure how optimistic that is...I should add that I have never tried tig and would need to buy equipment in order to do this project...I have owned an oxy-acetylene set for many years and have managed to get good results when need be...but never anything this thin...Regards,Gordon.
Reply:Originally Posted by gordonautI need to weld very thin sheet or foil...about 0.1 mm to 0.3 mm...in stainless T-347...can this be done with a tig welder...?Regards,Gordon.
Reply:Originally Posted by gordonautThanks for the info...The idea is to join two thin sheets arranged parallel to each other with a gap of about 2.5 mm between them...I was thinking of putting the copper strip in between and then laying a 2.5mm wire in the gap and resting on the copper...and then welding the thing shut...
Reply:Thanks again, D...I didn't really explain clearly what I had in mind with that wire...it's not meant to be a filler rod...it is basically a third piece of material...I would then proceed to make two separate welds...the one sheet to the wire...and then the other sheet to the other side of the wire...I have considered brazing but this piece that I need to build will see very high temperatures...my understanding is that the only way to braze for these high temps is in a furnace and in a reducing atmoshpere of some sort...preferably a vacuum...That is very expensive for a one-off piece...If hand brazing could somehow work then I would be happy to try that...the working temp of this piece when finished is going to be about 700 C...it's a heat exchanger for a gas turbine engine...Regards,Gordon.
Reply:Okay...I think microtig is going to be the solution for me...a little bit of searching turned up a UK company that makes what appears to be the most popular power supply for microtig...http://www.weldlogic.com/modelpa.phpThese are available used in good condition for as little as 650 lb sterling...Lots of options for micro torches out there too...And here is a video of one of these units laying down a tiny bead...and here is some really tiny welding...;the guy isn't even wearing gloves...Regards,Gordon.
Reply:in video 1 there's a guy with at least a few years of tig behind him , and the base material is a lot thicker then you want to weld.video 2 is laser welding.I would ask for a quote from a specialized company in micro if they can do it, it may be cheaper then you buying equip and with guaranteed better results if any.I googled a few hours last night about this and you don't have many realistic options, look at this http://www.lampert.info/jewellery.html--------------------------------------------------------------www.becmotors.nlyup, I quit welding.. joined welder anonymous
Reply:yes, I didn't realize that was laser welding...I looked at Lampert too but their unit costs over $5,000...Sunstone has similar equipment...but I think that weldcraft is the one best suited to my needs...I'm sure I could get a shop to microtig this for me...but the issue is the cost...there are over 300 pieces to weld up...each one consisting of over 1 meter of weld length...And then all those pieces have to be joined together in a certain way...I think that would cost a fortune to farm out...Regards,Gordon.
Reply:btw...here's a video of that Lampert micro welder...but it is really more of a spot welder...
Reply:Originally Posted by gordonautI should add that I have never tried tig and would need to buy equipment in order to do this project...I have owned an oxy-acetylene set for many years and have managed to get good results when need be...but never anything this thin...
Reply:Originally Posted by gordonautI'm sure I could get a shop to microtig this for me...but the issue is the cost...there are over 300 pieces to weld up...each one consisting of over 1 meter of weld length...Gordon.
Reply:With all the goings on about machines, techniques, and what will or won't work - what's the project?Photos would be even better.
Reply:Originally Posted by gordonautThanks again, D...I didn't really explain clearly what I had in mind with that wire...it's not meant to be a filler rod...it is basically a third piece of material...I would then proceed to make two separate welds...the one sheet to the wire...and then the other sheet to the other side of the wire...I have considered brazing but this piece that I need to build will see very high temperatures...my understanding is that the only way to braze for these high temps is in a furnace and in a reducing atmoshpere of some sort...preferably a vacuum...That is very expensive for a one-off piece...If hand brazing could somehow work then I would be happy to try that...the working temp of this piece when finished is going to be about 700 C...it's a heat exchanger for a gas turbine engine...Regards,Gordon.
Reply:Originally Posted by gordonautbtw...here's a video of that Lampert micro welder...but it is really more of a spot welder...
Reply:Originally Posted by DanTWith all the goings on about machines, techniques, and what will or won't work - what's the project?Photos would be even better.
Reply:Originally Posted by RojodiabloMy thoughts on this are to find a resistance welder; ie clamp or pinch welder. While there are a couple guys who might pull this off (Engloid comes to mind) I really don't see anything going down without MASSIVE warping.
Reply:Yeah, that is definitely a resistance welding item. Like the little Lampert welder delivers a shot of energy, this would be the way to keep the heat/ warping down. Seam welder is a more likely way to go.And then, after so much work...... you have it in your hand, and you look over to your side...... and the runner has run off. Leaving you holding the prize, wondering when the runner will return.
Reply:Originally Posted by RojodiabloYeah, that is definitely a resistance welding item. Like the little Lampert welder delivers a shot of energy, this would be the way to keep the heat/ warping down. Seam welder is a more likely way to go.
Reply:I do stainless steel window moldings for classic cars that have had the tops chopped.  These typically are about ,015-.019 thick.  The best I can get is .023 ss wire from a spool gun and straighten it with a very unique process....not mine.  The wire is still a bit too thick but does work.  The big problem is that most of the classice car SS is of unknown alloy.  The customers don't want to see the weld color so it forces us to shear very thin strips of scrap moldings.  These are never straight and vary in width.  They really complicate the welding process.Fortunately there is a grinding a finishing process after the welding so a high bead is ok and preferred.I use a number of copper backup blocks and strips.  I also use my double regulator and purge as much as possible.  The amount of gas used in a day is astronomical.The guy I do these for is a master metal worker and finishes these moldings like new.  Occasionally I have to fill in a dent and he calls this Stainless Bondo.Overall this is an extremely tedious and tiring process.  10 hours of welding this stuff is like a whole week of production tig welding crammed into one day.  I can say you need an extremely steady hand and at 70 I'm not as steady as I used to be.I use both my Lincoln 175 sq wave and the new Syncrowave 250.  Both work but I prefer my Lincoln as the torch is smaller and lighter.To answer the OP question....if you are low time tig welder this is going to be a monster of a problem.  It takes a lot of hood time and patience to develope the control required for this thin stuff and any unusual positioning or cramped welding corners will be even more of a challenge.
Reply:Can you pinch the edges of the sheet together and weld them as edge welds?  You could then pinch them in between nice heat sinks on either side, leaving just the edge sticking out past the heat sinks, ready to be fused together with TIG process autogenously (and probably a fairly quick travel speed).That would give you your best shot at manually TIG welding something this thin repeatedly and reliably (it could would make it easy for the right guy to do, actually, if you've got enough test material to dial in a technique with it first.)  Perhaps you could form the 2.5mm cavity inside the tubing after the edge welding is complete.Not to mention if you've got 300 of them to do, autogenous welding the edges is going to dramatically pick up your travel speed.  Also as an edge weld, you will not need to worry about backpurging and you will have a totally oxide free backside (or "inside".)While you are at it, you might as well just fabricate out of one piece per "tube" rather than two sides, so you'll only have one weld to do.  Fold one piece of sheet around a 2.5mm wide barstock.Last edited by jakeru; 07-31-2012 at 01:13 AM.
Reply:Jakeru...thanks for some good suggestions...I had considered pinching the edges together and thereby eliminating the need for a filler piece...however I figured that forming the piece in such a way would require special stamping dies which would be expensive...Plus there is a concern that the inside of the cell which is only 1.5 to 2.5 mm wide...could eventually collapse if there were not a filler piece to hold the sides apart...I had not considered the idea of bending a single piece and then having to make only one weld...that is a great idea if it can work...I do think this could be doable...not being a metalworking expert I cannot say for sure but I certainly hope to find out as this would definitely be the way to go...If nothing else it could be possible to just manually form each thin sheet around a wire rod of ~2 mm...but I will look into having this stamped out in some way if possible...If we could then just seam weld the other end shut then we would be in business...What dows "autogenously" mean...?...is that welding without filler material...?Regards,Gordon.Last edited by gordonaut; 07-31-2012 at 03:49 AM.
Reply:Bentwing...thanks for the input...It sounds like you are doing some very thin material with more or less standard tig equipment...with a power supply like that weldlogic that goes down to 1 amp or even less...plus one of the microtorches...it sounds like you could even go thinner yet...Regards,Gordon.
Reply:Originally Posted by gordonautThanks again, D...the working temp of this piece when finished is going to be about 700 C...it's a heat exchanger for a gas turbine engine...
Reply:Originally Posted by JoshfromsaltlakeHi, Gordon, I think what you're talking about is sometimes called a "recuperator"You're not just dealing with elevated temps, you're also dealing with high-flow pressurized gases. There's is no way in hell 0.3mm 347 is going to tolerate that at 700 deg. C.See for example, "stress on a clamped plate."http://www.efunda.com/formulae/solid...C_PUniform.cfmBtw...I should add that I have worked out the math in terms of structural strength needed to withstand the moderately elevated pressure on the cold side...that is not an issue...even with 0.1 mm foil...the reason being that the design includes support along the side walls...although I can't get into that because some of the design aspects are proprietary....But the thinner foil does not stand up to oxidation very well...which limits the recuperator's useful life to only several hundred hours...so that is why I am looking at going as thick as 0.2 to 0.3 mm...Regards,Gordon.Last edited by gordonaut; 07-31-2012 at 07:31 AM.
Reply:GordonautI'm just using plain machines although the Syncrowave does have all the options.I sure would like to try out those micro TIG machines. I'm right at the edge of control with these 2 machines.  I even use an 8 manual lens as the suto dark is too dark.  I use a halogen light on the work surface so I can see with the hood down.I designed 2 automated TIG welding machines years ago that welded battery cases.  This was done inan enclosed chamber in which we pulled a very low vacuum then back filled it with argon.  The Torch was just a collet assembly and electrode with no cup or hose since it was in an argon atmosphere.  x ray quality welds.......military stuff......cost was no object.
Reply:Originally Posted by gordonautJakeru...thanks for some good suggestions...I had considered pinching the edges together and thereby eliminating the need for a filler piece...however I figured that forming the piece in such a way would require special stamping dies which would be expensive...
Reply:Originally Posted by gordonautJosh, that's correct...a heat exchanger is used in the recuperation of exhaust heat energy in a turbine engine...The pressure on the hot side is atmospheric...on the cold side...which is the flow coming from the compressor...the pressure ratio on this engine is about 4...so that is about 4 times atmospheric pressure...about 60 psi absolute...or 45 psi gauge (at sea level)...which is not very high...recuperated engines work best with low pressure ratios...Thanks for the link...I'm an aerospace engineer with lots of experience with turbine propulsion engines...so far none have used the recuperated cycle successfully...that is the idea behind this project...
Reply:Originally Posted by jakeruI wouldn't think it would be hard to form due to how thin the material is.  If you can get it in a softer work hardening state (that is called the material's "hardness", and may be available in for example, annealed, quarter-hard, half-hard, full-hard, etc), that would make it more formable.  Full hard material would probably not be a good idea.  With it quarter-hard or annealed especially, it shouldn't take that much force to get it to move how you want it to.Maybe you could form a flange in one or both sheets, in preparation for edge welding, with an inexpensive hand-held flanging tool (such as attached).  There are also tools that give similar results using rollers that cost more, but might be worth it given you have 300 of these tubes to fabricate.  I'm not sure how long each tube is, that would definitely be a consideration.The other way would be, weld it first, then afterwards, form in some volume inside somehow (like inserting a wedge or strip inside to deform the tubing outwards) after the welding is complete.  (The welding would actually anneal the stainless in the heat affected zone near the weld, so it may form that way a lot easier than you might think.)Yes, that's right; Just melting two pieces together without adding any filler rod.  The attached picture shows .012" thick copper sheet being edge welded autogenously using the manual TIG process, as an example.  In this example, the sheets were not restrained by clamping as I suggested, but they were tack welded about every inch to keep the sheets from pulling away during welding.  The edges need to be kept very close - ideally touching - for this to work.