Getting soot when I MIG aluminum

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I am relatively new to MIG welding of aluminum and seem to be having a soot problem.  I know the welds are messy too, but I wanted to figure this out first.  I am using a Hobart 210 with spoolgun and100% argon and 0.030 4043 wire.  The regulator is set at 25cfm when the gas is flowing.  I have been trying this on some scrap "U" channel aluminum I bought but was not labeled, so I am not sure what type it is.I am curious what I am doing to cause so much soot.  Once I stop welding, I can see little red hot "burning" embers run through all the soot, almost like when steel wool burns. I am brushing everything with a SS brush prior to welding, and have checked to see is gas is coming out of the hose on the spool gun.
Reply:Try to push instead of pull on al.PeterEquipment:2  old paws2  eyes (that don't look so good)1  bad back
Reply:These were made while pushing, i am guessing i held it at about 15 deg.
Reply:Crank your flow meter up to 40 or so, push the weld at a slight angle, pay attention to your stick out, avoid drafts.
Reply:You may want to spray your argon connections with soapy water make sure you dont have a leak.   Like they said push  with a 15+deg angle and keep a shorter arc length.  If your arc length is too long you can have sooting problems even tho every thing else is correct.“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:Always use the "push" technique when MIG-ing  Al. Your biggest problem is likely to be improper settings.  Best settings for 030 wire is about 550 in/min and 22 volts. Buy a voltmeter if you need one.  You can use a stopwatch to get a good estimate of the feed speed. Just pull the trigger for 6 seconds, measure the amount of wire hanging out, then multiply by 10Most of the black soot is actually finely powered aluminum+aluminum oxide. The boiling point of Al is around 4450 degrees F. whereas the arc can be 6,000-12,000 deg. F. So if you have unstable metal transfer, the arc will tend to vaporize some of the the molten end of the wire. Excessive soot may indicate erratic metal transfer. In turn that is most often caused by less-than-ideal settings. Some soot is inevitable.I like to use slightly higher gas flow rates with Al, I use about 40-45 CFH.Clean your welds off with acetone or alcohol. Then use a stainless wire brush, or even better, a wire wheel attachment for a grinder. Some people on this site recommend oven cleaner. I haven't tried that.  Cleanliness is very important with aluminum MIG, more so than when TIG welding.
Reply:I got the same soot; much less but a pretty good bit, when  was GMAW on Delta II rockets. That was 2014 aluminum and I know it was cleaner that school marm pu,,,,,,,,,,,,,,,,,,,,,well it was very clean. Funny thing about it was inside that dark space, when you lifted your shield, the soot had a trail of fire that took off from your termination and went all the way around the circumferential weld to the start point.  Not a flaming fire but more of a glowing spark that was chasing the soot around the weld.  Strange. My engineers were baffled as to this phenomenon as well.Two turn tables and a microphone.
Reply:I've seen that orange glow go around the weld when I finish a few times.  It's really cool  reminds me of the terminator movies when they get sent back in time.  2 things that also come to mind.   Bad ground.  If you dont have a really good ground sooting happensAnother reason I had sooting problems is the Aluminum was damp.  It needs to be dry.  Ive used rod ovens or stored it with a 500 watt buld on it so it didnt absorb moisture overnight.  the rest is all about cleaning pass after pass.  The stainless tooth brushes are what i use.  I mostly run .035 or 1/16"  al.  So my settings are lil different. Josh gave you a good base line to start with. Start there and tweak it slightly till you start to see cleaning action. If your using a cleaner DO NOT USE cloth that has been dyed. Cheesecloth works the best wont leave a residue.  Aluminum is very porous.  It absorbes impurities weakening the weld area. Attached Images“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:Originally Posted by PangeaFunny thing about it was inside that dark space, when you lifted your shield, the soot had a trail of fire that took off from your termination and went all the way around the circumferential weld to the start point.  Not a flaming fire but more of a glowing spark that was chasing the soot around the weld.  Strange. My engineers were baffled as to this phenomenon as well.
Reply:I would turn up wire speed, and voltage down a touch.Dynasty 200DXPassport plus w/ spoolmate 100victor 315c oxy/(act and prop)Miller digital elitemilwaukee power tools
Reply:Thanks everyone.  I will give all of these a try (I am going to get some new aluminum today) and will post some pics to show how each of these did.Thanks!!
Reply:Another good habit to start now is crater filling. At the end of your welds pause an extra second and fill that craterIf you don't. 99% of the time it will crack.“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:Here are the things I did this evening:spray your argon connections with soapy water - I checked everything from the tank to the gun.  I even took everything apart to check internally (solenoid).  There is a very small leak where the air tube goes into the main hose connection.  It looks really small though.Always use the "push" technique when MIG-ing Al. -   I did my best here.Best settings for 030 wire is about 550 in/min and 22 volts - I did the test and found I was at about 480, I sped it up to 550 which is about 90 on the Hobart.  I measured the voltage and found it to be 28V@#6.  So that is high, but I am not sure whatit would be when in actual operation.higher gas flow rates with Al, I use about 40-45 CFH - Set to 42.Clean your welds off with acetone or alcohol - used some acetoneBad ground - This is interesting because I think that the clamp that comes with the hobart seems a little crappy.  It could very well be the case.  I have to figure out how to test this further.Something seems wrong with the spool gun now since I took the cover off it.  If you look in the last photo, the wire is now coming out sideways.  I can actually seethe wire curling out while operating, so it is not staying "centered" in the "work area". Also, the motor seems to start a little slow, and then speed up in half a second.  I think I might have misaligned something when rassembling.Here are some photos with soot, and with soot removed for comment.  I can tell that I start out with the metal cool, and as it heats up, I am trying to move faster, but in the end I get a crater because it is starting to melt through (1/8") at the end.  This is 6063 aluminum and the width of the piece is 1.75" just so you know the scale of the pictures.
Reply:Resize your pics.
Reply:You might notice that I am having some image issues.
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Reply:Is there any chance that the alum is coated with a clear coat? Try welding on another piece or right over one of the welds on your practice piece. Just a thought
Reply:Soot happens! It wipes off after you are done and it doesn't really seem to affect weld performance. I think your issues are all technique related. Try working with your setup, remembering this is spray arc, not short circuit. Turn it up hot, pull the trigger and haul arse, pushing the gun. If you pause for a second and it does not burn through, leaving your weld in a puddle at your feet, you are doing something wrong.
Reply:thomas, my opinion is the weld is TOO  hot, turn it down!The lead is OK but the absence of a narrow clear track next to the bead seems to indicate you may need more argon.Both 5356 filler and 4043 will break down when they are in spray mode, with extremely long arcs. This means the alloy becomes separated and the magnesium deposits out and then flashes from the charged capacitance left from the over powered spray.  The soot is normal for Aluminum MIG; all Al MIG. The beads you show are flat, pointed and sagging, so that makes me conclude the amperage is way, way too high.I have welded aluminum for a while and I prefer to weld between spray and short arc.  So working in that 'cusp', or point of change, allows many welders who use this method to have the spray to wet the area, then they whip the puddle in a micro sized lower case 'e' or 'c' and that change in R (tip to work) allows the weld to cap in short arc mode, resulting in a different look than you're using.I'd turn down the power, up the argon, and adjust the wire to burn/deposit more uniformly.Others have suggested different methods that probably work for them, but this is the idea/method/concept I use.Cheers,Kevin MorinKenai, AK
Reply:Thanks for everyones help! I will keep practicing and experimenting to get everything looking good.
Reply:Originally Posted by thomaskuhnThese were made while pushing, i am guessing i held it at about 15 deg.
Reply:silly question, you have pure argon and not the co2/ argon or trimix blend for steel, right?  ( I have never tried aluminum mig with the wrong gas so I dunno if this could be possible or not)miller syncrowave 250hobart handler 140home made 400 amp engine driven in progress...
Reply:Lots of reasons, dirty liner, dirty tip, bad gas, dirty material, wrong gun angle, etc..... eliminate the obvious first.Disclaimer; "I am just an a$$hole welder, don't take it personally ."