Stud Welding Aluminium

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Not quite welding but, closeWe're trying, with no success to stud weld Threaded M6 studs to some Ali we are fab'in at work. And for the life of us all we cannot get the bloody things to stick. It doesn't matter what power setting we have it on, whether it's wire bushed and wiped down with alcohol, or not. They come off with little effort.Any suggestions appreciated
Reply:Can't seem to find much info on the web.    This site mentions that the aluminum stud should be positive polarity, versus steel and stainless which uses negative polarity.  Also says alluminum may need inert shielding.http://www.welding-advisers.com/Stud-welding.htmlAny pictures of your welds?  So basically, do you think the weld needs more heat?  What is the base metal thickness, maybe this is a factor?Another article, didn't see if it mentioned polarity.http://findarticles.com/p/articles/m...n21316441/pg_1Last edited by pulser; 06-16-2008 at 05:19 PM.
Reply:I read the same web page.I figured the Stud need to be +, and have tried it, it did help but not much.The Base material is 3mm (1/8").The machine is a Discharge type, and I've had it blowing holes in the 3mm base. I did try Flux Powder, for gas welding and it again helped a little but they still twist off with little resistance.I'm going to try preheating the Base metal tomorrow, and see what that does. Unfortunately (yeah rite oh) I'm off to a bike rally in The Shetlands tomorrow night so I'll not be able to post pictures or results until next Tuesday. The job needs to out Tuesday night nd I have already started to weld the peices to the base instead of using threaded studs, however it would be nice to get it to work for the next time we use them.
Reply:clean, clean, clean! oxides form very quickly. clean- shoot stud, clean- shoot stud, clean- shoot stud.
Reply:believe me we have, to the extent, I've had a lad cleaning the base with a SSteel Bush with Alcohol rub in the other hand, right before I try and dab it on.ArrrrrrrrrrrrrrrrrrrrrrrrrrrrhIt not like I don't know what ALi is like to weld, that and SSteel is the only thing we touch
Reply:how many studs are you talking about? Is hand welding a possibility?
Reply:A lot. The sheets are 12'x6 that make up a large Sign, Raised letters are fitted to the face, This one is about 35yds long and 6' High.The studs hold a male and female connector that holds the sheets together down the vertical joints. 20 per joint. There's no weight on them, just stops the joints from opening. I'm welding them on at the moment but Studing them would be better as it would be quicker
Reply:any way rep out there filler or stud?
Reply:this may well be impossible for your situation if you cant reach all the locations .... but inertia weld them?   take a stud and chuck it in a vertical mill collet.wind the mill up, turn it off, and slam it into the sheet letting it coast down from a decent RPM.  and un-clamp.just a thought.
Reply:does the machine have a gap mode?
Reply:Even some steel applications require ceramic ferrules (with deoxidizers) in order for stud welding to work.  The same may be true for aluminum.  For sure, the oxides should be displaced from the weld.  The weld would have to squish out from under the stud for that to happen.
Reply:WOW 6' X12' sheets!!! One is 35 yards long!!!!!No wonder you are having problems.The sheet of aluminum would take a LOT of heat before it ever got hot.You would have to just about have to get the stud to the melting point.I would just drill and rivet the panels together.ALSO you could use PEM nuts, (pressure engineered machinings) nut plates, that you could use a hydraulic press to install.Last edited by Donald Branscom; 06-17-2008 at 08:17 PM.