aluminum help

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Been practicing with my new tig machine... tig is an amazing process with which to weld...but I am running into some trouble while doing some practice welding on some aluminum intercooler piping.I have a few dozen feet of 3" OD mandrel bent aluminum tubing (~.085 wall?) which has been pulled from customers trucks as they upgrade to larger turbo kits (which come with mandrel bent mild steel tubing)so...I have ALL of this piping around...and if I can figure out how to get a decent weld on any of it, it will come in handy when fabricating other projects...I *think* the real problem with this particular tubing is that ALL of it has previously been run on trucks where the crankcase breather is redirected back into the turbo inlet...so all the pipes have been exposed to months/years of a nice hot oil mist being blown through the inside...I've tried wire-wheeling off the (factory) aluminized-ish "paint" back 1/4" from  the ends prior to welding...and a general wipe down with clean rags (no solvents, yet) but the weld puddle sort of 'skins over' as I'm welding this tubing back together...compared to you folks, my beads are pretty rough...but I can lay a (comparatively) decent stringer on some bits of scrap alum diamond plate sheet...but this tubing is kicking my arse!  any magic you folks can offer will be appreciated~take care~Dave
Reply:Welcome to the forum Dave. Yes, tubing is difficult. Get comfortable and practice, practice, practice. No magic...just practice like anything else you learn...you do it long enough, you either become good at it or quit. John -  fabricator extraordinaire, car nut!-  bleeding Miller blue! http://www.weldfabzone.com
Reply:Hey Dave,Welcome to the web!I "think" you've already identified your problem as the cleanliness of the tube.If you have some acetone, give the tube a really good wipe down and try again. If you don't have any acetone you can use some NON-chlorinated brake cleaner or some other form of degreaser/cleaner.It sounds as if there is still a good amount of "crap" on the tubes. Are you sanding the inside of the tube as well? If not, you might want to hit it with a little bit of sandpaper.I always wipe down aluminum with scotch-brite and acetone before I weld it.Also, what are your settings and consumables?Give it a shot. Post a pic or two if you can...that would help a lot in figuring out exactly what the problem is.- Paulhttp://all-a-cart.comWelding Cart Kits and accessories
Reply:*zoinks*  so the 'skinning over' isn't contamination...just technique? wow.. I DO need to practice, LOL! I am really surprised at HOW dang hard it is to get the aluminum to act right...any good products to recommend on cleaning the tubing prior to tig?xylol? MEK? HelP? Millermatic 251Syncro 200
Reply:hey golfer,the 'skinning over' could be lack of cleanliness and/or techniqueas said, cleanliness is very important with Al. degrease first (NON chlorinated brake cleaner, acetone etc) and then remove the natural oxide coating with scotchbrite or a STAINLESS steel brush. scotchbriting the filler is a good idea toothe oxide layer has a melting temp around 3 times that of aluminium (you can melt the Al and still have a skin of solid oxide laying on top). the oxide layer begins to reform imediately which is why AC is used.the balance setting determines how much is removed by the arc (different machines perform differently here). start at around 65% EN and adjust from there- more EN gives less cleaning. if all is good the puddle will be shiney with no trash floating in it.torch and filler angles are more critical with Al and harder to keep correct with tubing as they're constantly changing. have a look at http://www.millerwelds.com/resources...ur-skills/tig/, the tig hand book covers torch and filler angles and much more
Reply:Hey Dave(golfer),I do agree with the previous posts and can only add that you may want to consider cleaning the weld area to at least 1 inch or a bit more. Also, a drum sander to do the inside will help and I also highly recommend acetone and a vigorous brushing with a SS brush to the weld area just prior to welding. You will find aluminum to be quite finicky and chemical cleanliness is an absolute must. And......PRACTICE!!!!!! It only makes you better and provides answers to issues or problems......Good Luck....DennyComplete Welding/Machine/Fab. ShopMobile UnitFinally retired*Moderator*"A man's word is his honor...without honor there is nothing.""Words are like bullets.... Once they leave your muzzle, you cannot get them back."
Reply:Originally Posted by hotrodderthe oxide layer has a melting temp around 3 times that of aluminium (you can melt the Al and still have a skin of solid oxide laying on top).
Reply:[IMG][/IMG]this is a clean(er) piece of scrap Dplate which was wiped down with MEKThis weld is MUCH better than those on the 3" piping...I'm having trouble keeping the pool from getting pretty wide...looks to be just under 1/2", and from looking around at y'alls welds...they look to be 1/4-5/16" wide.Also, [IMG][/IMG]this shows hardly any penetration...so I figured I would be able to break the weld rather easily...so over to the bench vice [IMG][/IMG]and I tried to bend it over and break it...also tried twisting it to try to break it...surprisingly the weld is probably (sufficiently) strong due to the width of the weld...not due to penetration...so it didn't snap  I'll get a stainless bristled brush for cleaning prior to welding...and get a scotch brite pad (or ten) and keep them for alum use only.I'm still learning how to use/apply the pulsing feature of the Syncro200...but it was on...set to 9.5 (min is 0.1, max is 15.0) though I don't know what units...pulses per sec? maybe...I set the upper limit on the voltage to about 100-110...and never went past 3/4 pedal...guessing I was running @ 80ish volts...and about 15CFH on argon.thoughts?thanks~DaveMillermatic 251Syncro 200
Reply:Overall I don't think you're doing a bad job at all for just starting on aluminum.As you mentioned...maybe a little wide on the bead....even looks a little hot to me.What is the thickness of the diamond plate?What size and grade of filler rod are you using?Are you using the pulse feature of the sw200? Any pics of how your tungsten looks after those welds?- Paulhttp://all-a-cart.comWelding Cart Kits and accessories
Reply:Yes i agree, looks to be a little hot, and wide.  one thing to remember aluminum heats up fast.  When welding aluminum you will be able to ease up on your peddle a bit and gradually run cooler as you go to keep the puddle the same.  In other words it takes less heat at the end of the weld as it does at the start.  Looks like you are getting the hang of it.  Keep practicing.I'm a Lover, Fighter, Wild horse Rider, and a pretty good welding man......
Reply:Originally Posted by golfer[IMG][/IMG]this is a clean(er) piece of scrap Dplate which was wiped down with MEKThis weld is MUCH better than those on the 3" piping...I'm having trouble keeping the pool from getting pretty wide...looks to be just under 1/2", and from looking around at y'alls welds...they look to be 1/4-5/16" wide.Also, [IMG][/IMG]this shows hardly any penetration...so I figured I would be able to break the weld rather easily...so over to the bench vice [IMG][/IMG]and I tried to bend it over and break it...also tried twisting it to try to break it...surprisingly the weld is probably (sufficiently) strong due to the width of the weld...not due to penetration...so it didn't snap  I'll get a stainless bristled brush for cleaning prior to welding...and get a scotch brite pad (or ten) and keep them for alum use only.I'm still learning how to use/apply the pulsing feature of the Syncro200...but it was on...set to 9.5 (min is 0.1, max is 15.0) though I don't know what units...pulses per sec? maybe...I set the upper limit on the voltage to about 100-110...and never went past 3/4 pedal...guessing I was running @ 80ish volts...and about 15CFH on argon.thoughts?thanks~Dave
Reply:thanks for the encouragement  hopefully I can keep improving.---The tungsten looked pretty horrible after that pass...like the end just burned up, LOL.  so maybe I'll turn the heat down a tad. And the arc was all over the place...so I just kept stuffing rod in there...I don't know what the specs are on the filler...whatever the guy gave me when we picked up the machine last Friday.As far as am I using the pulse feature... I *think* so...still trying to figure out what does what...maybe time to read over the manual again...I may have not have been on pulse...but on whatever the squarewave button thingy... I think that's the ratio of on time vs off (lower volt?) time...I guess I'll need to spend as much time remembering WHAT settings I am using when test welding to give you guys as much info as I can...I sure do appreciate the feedback though...take care~DaveMillermatic 251Syncro 200
Reply:Another thing to try out on your syncro -- turn the balance to 10.  The clean width even with balance set at 10 is plenty.  Will be a little less tough on your tungsten and give a little more arc focus. (not a whole lot, but a little).Favorite right now is a Miller Syncro 200.Tons of tools and I blame at least one of them when things don't go right.