new to aluminum, question about sooting.

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Hi all.    Ok here it is, yes I am relatively new to welding for those of you wondering here is my background experience. 1/2 hr to an 1hr of Oxy, 0Hr stick, about 5 - 6 Hrs or gasless wire welding, and about 2 Hrs of Mig welding aluminum. Yea I know, I like to dive in head first but I am a quick learner, however. I am having a little trouble figuring out why my welder is doing what it is doing. Project info... basically all I am doing right now is some intercooler piping for my car. Nothing structural just welding some 2.5" aluminum piping that will see no more than 35Psi of air pressure Max. Now while my welder isn’t the best in the world I did manage to get it set up well enough to make an acceptable weld for my purposes (only took me about an hour to figure the welder out). I am using 100% argon shielding gas but no matter what technique I use (push/pull) or how hold the gun (angled/straight up down) or how close/far from the work piece I am my welds end up with black soot all over it. The tank I am using was given to me by my father-in -law and is quite old but was just recertified, is it possible that it just isn’t clean anymore and I am just not getting good clean argon from it?Any help you can provide would be much appreciated.ThanksMike
Reply:guess 1  would be contaminated tungs. grind if you dipped it 2.. too much gas or nonetoo much gase 12-15----20 CFM not psi ac current ,HF turned on, clean clean clean alum SS brush ,an acetonemore ifno on machine and setting will help dio your prob PICS helpidealarc 250/250 ac-dc tigidealarc 250/250 ac-dc tig #2 used for sticklincoln sp100hh125dual arbor grinder polisher30 yrs of hand tools52 pitch blocks 6p-26prake gauge -pitch gaugeG&D prop repair 918-207-6938Hulbert,okla 74441
Reply:it sounds like he is running migDynasty 200DXPassport plus w/ spoolmate 100victor 315c oxy/(act and prop)Miller digital elitemilwaukee power tools
Reply:Yes, using DC MIG not TIG.10 - 20 CFM argon flow? Or would those settings be more for TIG? Everything I have been reading so far has been telling me 20 - 25. So maybe I need to go lower than I am now??? Think the lowest I have been going with my setup is 18. Could it be a clean part issue then as well? The way I understood it was that I wouldn’t get a good weld if it wasn’t clean enough. The welds are pretty good and they look like I am getting pretty good penetration, they are just covered with black soot when I get done.I will have to fire up the rig tomorrow and get some PICS of the welds. I’m at work right now and most of the work I have already done has been ground down and smoothed out for polishing. As for the machine I am using. It is a Century 155 that I converted for use with aluminum. Both the wire speed and voltage are turned all the way up. No spool gun. But I found that the closer you have the wire tube to the roller the less likely it is to bird nest. :PLast edited by mikec96; 02-17-2011 at 02:43 PM.
Reply:OOPS  my fault mig will give of soot but cleans off easyidealarc 250/250 ac-dc tigidealarc 250/250 ac-dc tig #2 used for sticklincoln sp100hh125dual arbor grinder polisher30 yrs of hand tools52 pitch blocks 6p-26prake gauge -pitch gaugeG&D prop repair 918-207-6938Hulbert,okla 74441
Reply:Usually just changing the angle does the trick.   What position are you welding in btw?Have you put your hand up to the gun to see if the argon is flowing correctly.  It sounds like you have bad argon flow.   You should be up around 20-25 cfmPlease post a pic of your machine and gun.  I cant picture the machine your using.Last edited by galencwi; 02-17-2011 at 03:17 PM.“I'm going to do the thing that God put Galen Beasley on this Earth to do:Have Salon quality hair and weld.Nothing like a good cup of coffee and the smell of 6010 burning in the morning. 971-204-3444 cell API ASME Structural NDT and Repair
Reply:If you have the right angle "" pushing 7 to 10 degrees forward ", there's shouldn't be too much soot, not on the weldment anyways. But you're still will have some soot.
Reply:Originally Posted by galencwiUsually just changing the angle does the trick.   What position are you welding in btw?Have you put your hand up to the gun to see if the argon is flowing correctly.  It sounds like you have bad argon flow.   You should be up around 20-25 cfmPlease post a pic of your machine and gun.  I cant picture the machine your using.
Reply:Hey mikec,You also need to provide info on the wire type & dia.(4043/5356/.030/.035). Soot is gonna happen with MIG. I generally run 18-22cfh of Ar indoors. Try to turn both your heat & wf down a bit & some experimenting on some scrap pieces. Your gun angle should be close to 90* & about 3/8" stickout. Your tip should be .005 larger than the dia you are using, ie., .030 dia wire, .035 tip orifice, .035 wire dia, .040 tip orifice. Always cut the wire prior to starting as this will lead to better starts & less burnback. You want to "PUSH" feed the wire & only PULL if doing an inside corner on occasion. Remember, alum. runs hot & fast, & your travel speed & stickout distance consistency will render better welds.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 mikec96by position are you talking mainy about how i am holding the gun? normally it is right in front of me i try to keep it angled to one side or the other depending on which direction i am moving the weld but 9 times out of 10 it is angled slightly to the right and i am pushing the weld to my left. as far as argon goes i would say yea it is flowing how well out of the gun i am not sure exactly. with the welder off i can here the flow when i pull the triger and yes you can feel the flow, unfortunatly i dont really know what 20 - 25 CFM feels like.i will see what i can do about getting a pic of it up tonight.
Reply:Originally Posted by yorkiepapHey mikec,You also need to provide info on the wire type & dia.(4043/5356/.030/.035). Soot is gonna happen with MIG. I generally run 18-22cfh of Ar indoors. Try to turn both your heat & wf down a bit & some experimenting on some scrap pieces. Your gun angle should be close to 90* & about 3/8" stickout. Your tip should be .005 larger than the dia you are using, ie., .030 dia wire, .035 tip orifice, .035 wire dia, .040 tip orifice. Always cut the wire prior to starting as this will lead to better starts & less burnback. You want to "PUSH" feed the wire & only PULL if doing an inside corner on occasion. Remember, alum. runs hot & fast, & your travel speed & stickout distance consistency will render better welds.Denny
Reply:soot happens.... lol.... (couldnt help myself) mig aluminum is sooty... it is what it is. i can say that aluminum likes to be pushed using straight stringer style beads. basically, no torch manipulation i.e. the weave or wobble.... as yorkie said a 3/8 stickout is ideal, but you should look at about a 6 to 10 degree lead angle from perpindicular. aluminum also likes the spray transfer, short circuit transfer only gets you cold lap and incomplete fusion in the toes of the weld.i didnt see you mention the type of machine used, but i can tell you the parameters that i use on coded aluminum using a xmt304 and xr-a push pull feeder running .035 wire 5356 alloy. on 1/4 inch and above, i am running 25 to 26 volts and 700 to 800 wfs which of course will depend on ambient temperature and a few other variables.the biggest thing you should know about aluminum is this: cleanliness really does = godliness. aluminum forms a protective coating called oxides. you can brush it, rub it, polish it, acid wash it makes no matter, the oxides will start to form immediately. molten aluminum is more reactive to the atmosphere than standard a-36 carbon steel is and there are a couple more precautions that you have to take when welding it.no grease, oils, water or anything on it. i dont prefer mechanical means of oxide removal because you can smear the surface of the metal and bury the nasties only to bring them out to the surface while welding. i shape with a file, clean with acetone, then rubbing alcohol, then hit it with a hand SS wire brush (key note Stainless steel brush that has never brushed anything except for aluminum)some might consider my aluminum antics to be extreme, but i like to turn out perfect perfection and therefore, i gain much repeat customers and get to score the big "non-disclosure govt jobs"hope that ive helpedmigweld 250parcmate 205weldall 250piforcecut 80i plasma'07 pro 300 miller'08 trailblazer 302mm350pdynasty 700dynasty 200deltaweld 452xr-a 50ft push pull feeders and gooseneck
Reply:"It's OK to have a small amount of smut on the parent material outboard of the cleaning stripes. It's also common to see smut at starts, stops, and at corners. However, if the entire weld is coated with smut, you've done something wrong."http://www.thefabricator.com/article...mize-weld-smutBTW it is CFH  Cubic Feet Per Hournot CFM- you'd be outta gas in a minute if you set yer Gauge to 20CFMEd Conleyhttp://www.screamingbroccoli.com/MM252MM211 (Sold)Passport Plus & Spool gunLincoln SP135 Plus- (Gone to a good home)Klutch 120v Plasma cutterSO 2020 benderBeer in the fridge
Reply:i was just thinking that broccoli... CFM is a lot of gas. and yes normally the weld is covered in black smut... i will read that link here in a bit. dinner is about done.OK wife is still in the process of making dinner so i snapped some pics of the welder. i will try to see if i can get some pics of the welds tonight but it will more than likely be tomorrow for those.first pic is the front of the welder exactly as it was the last time i used it... not sure why i was messing with the wire speed must of thought it was the voltage accidental.second pic is exactly where the regulator was set last use. all i did for the pic was turn the bottle on and pull the trigger on the gun to show how much flow i am getting.Last edited by mikec96; 02-17-2011 at 09:47 PM.
Reply:thanks for the link B. i think that may have actually helped me out a bit. so after reading that from what i can gather i have a few things to try. from what i can tell the way i am holding the gun is OK, short of having someone who knows what they are doing come and watch me all i can do is assume that part is good. i suppose some schooling would help but at the moment i have neither the free time or money for that. so the plan is try a little different cleaning technique, i haven't been using and chemicals to clean with, i have been using sand paper to get the rough clean down followed be a SS wire brush before welding. also from that read and probably the more important part is it sounds like i need to get the gun a little closer to the work piece to get the weld more into the argon shield. lower the temp a little and play with the wire speed to see if i can keep the burn backs from happening. maybe leave the WS where it is now and start turning the voltage down until i get a colder weld/not really welding more of just making a mess out of the work piece. then bring the temp back up a little and adjust wire speed until the weld looks good? or just turn the voltage down a little bit and play with wire speed? the second option sounds more correct.and of course practice. practice. practice. thats partly why i am using my car as the guinea pig for this. i don't have a lot of scrap lying around or the money to buy a lot of scrap to practice on, that and the NEED to try to get this car running before i lose all interest in it and i sell the thing. so that is why at the moment what i am doing know is more like practice than anything else anyway (it will eventually all get redone once i get a better at this welding process and i get new piping). i have tomorrow off so while the wife is out riding her horse and my son is over at his friends house (yes he has the day off also which gives him a 4 day weekend) i will hit up the garage and trough some heat on the piping and see what i can come up with for a cleaner weld.thanks everyone for the advice.. it is almost 10pm so i am calling it a night. i will keep you posted...mike
Reply:Say tubing not pipe.Soot on aluminum is contaminants. Clean with a stainless tooth brush before welding.Try using less gas pressure.AWS certified welding inspectorAWS certified welder
Reply:well after a couple of days of messing with the welder i have started getting closer to what should be a better weld, however as i do it has started becoming more apparent that it may be time for a mew welder... not really surprising but not really something i can afford anytime soon. anyway i will kind of give you the cliffs notes of the last couple of days. let me know what you think. Friday started welding, about normal for me covered in black. played with both the voltage and the wire speed for a little bit and after about 10 or so beads the black started going away, and i was able to get the gun a little closer to the work piece. Friday start.started running out of room so i changed to a different work piece. and got i t better dialed in.after a couple more fine tunes i was able to get some welding done that didn't look nearly as bad an required very little cleaning. the 2 welds that are circled i didn't take a wire brush to at all prior to taking the picture.so i changed to my third work piece and couldn't get a solid clean weld to save my life... the welder just kind of spat the aluminum on the tubing in chunks and blobs the the welder would bog down like someone trying to drive a car up a hill in the one to high of a gear.so i figured that it was time to give the welder a rest for a bit and take a brake myself. i let everything cool down for about 2 hours or so and then made one more attempt at welding for the day and it was like being right back where i started that morning eve though i hadn't made any changed to the welder what so ever during my brake. Saturday roles around and i basically started the entire process over only i didn't have to make as many changes as i did on Friday. only this time after getting a halfway "OK" weld i start getting the bog down noise for about 1/2 a second then the welder caught and wasn't doing to bad for about 5 seconds then it just started spitting globs of aluminum at the tubing that really didn't do anything... (the coupler was kind of just shoved on there after the piece cooled for a bit)i might go mess with it one more time today just to see what i can come up with.
Reply:Originally Posted by Broccoli1"It's OK to have a small amount of smut on the parent material outboard of the cleaning stripes. It's also common to see smut at starts, stops, and at corners. However, if the entire weld is coated with smut, you've done something wrong."http://www.thefabricator.com/article...mize-weld-smutBTW it is CFH  Cubic Feet Per Hournot CFM- you'd be outta gas in a minute if you set yer Gauge to 20CFM
Reply:One thing with running mig aluminium is you will go thru a lot of consumables( tips ) when your learning.   Depending on how your machine runs the wire can burn back on the tip and affect the wire feed.   If you dont have a lot of new tips then try cleaning your tip every once in a while to make sure nothing is interfering with the wire feed when you experience sputtering like that.“I'm going to do the thing that God put Galen Beasley on this Earth to do:Have Salon quality hair and weld.Nothing like a good cup of coffee and the smell of 6010 burning in the morning. 971-204-3444 cell API ASME Structural NDT and Repair