MIG AL project. Need help soon.

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So, working on this aluminum basket-like object. It is 20 vertical fins snapped together on these gear-like rings. Provided a few pics below. We waterjet-cut little notches in all the parts so we can just snap it all together and go. All is well so far, we have to make fillet welds at every joint. the fins are cut from 3/8" but the rings are cut from 1/4", all 5052 AL I believe.  The rings are about 3/4" deep, so there's not much area for the weld. I've had intermittent success working around 26V, 29 arc, and 600ish wirespeed, with .035 wire. I've tried varying between 25 to 30v to hone it in and fiddling the wirespeed a bit, but I'm not having any luck nailing it down.  This is spray arc, btw. I feel there is just not much penetration and extra voltage seems to just make things ugly without much more punch. Been on this for a while and I think I'm hitting my wall. I'd love any guidance on this matter.
Reply:Well you could start at the open end of the joint. Starts tend to be cold with alum mig so the open end will heat up faster. Then as you work your way to the more solid part of the joint you will have some heat built up in the metal, terminating at the inside. Then you could dress your starts for appearance. 4943 filler wets like no tomorrow, and coupled with Ar75/he25, you will get a smaller weld with more penetration. You could also bevel where your start is and dwell a tad there before moving to the inside. At least you will have your penetration there. Are you breaking the oxide layer at your welds before assembly?Weld like a "WELDOR", not a wel-"DERR" MillerDynasty700DX,Dynasty350DX4ea,Dynasty200DX,Li  ncolnSW200-2ea.,MillerMatic350P,MillerMatic200w/spoolgun,MKCobraMig260,Lincoln SP-170T,PlasmaCam/Hypertherm1250,HFProTig2ea,MigMax1ea.
Reply:Judging by all that black smut I see it looks like you're probably pulling the puddle.   You need to push it.And like shovelon's already said, start on the open edge (where you've been stopping) and work back into the joint and wrap it around the back side of the ring piece.
Reply:Seems like way too much wire speed and voltage for .035.
Reply:yea 035 is too small for what your doing id switch to 047 5356 but thats my prefrence with your setup id hit 26v 500 wire with the 047 and turn your argon up to 40 or more.   i did notice you said water jet cut so are you doimg any cleaning befor welding ? of not the joints need to be cleaned water jet imbeds sand into the alu.High Octane Welding
Reply:Have to work from the outside in unfortunately. This thing is a tight squeeze and going to get tighter as we add the rest of the parts.  Parts are all stripped of the mill and brushed down at the joint just previous to welding. Ive been starting the weld about 1/2" front the joint on the plate to "use up" the cold start before I get into the joint. You can sort of see it in the 1st pic. Ive been beveling the thicker plate to get the metal thickness closer to the 1/4" rings.Last edited by Edward Bil; 09-24-2014 at 02:06 PM.Reason: Number
Reply:I am pushing the wire. Smut is for some other reason.  Does the 4943 or 5356 bond well enough with 5052? Thanks abec and shovelon for the specific help. With my clarifications, any other factors that could be in the way?
Reply:Originally Posted by Edward BilHave to work from the outside in unfortunately. This thing is a tight squeeze and going to get tighter as we add the rest of the parts.  Parts are all stripped of the mill and brushed down at the joint just previous to welding. Ive been starting the weld about 1/2" front the joint on the plate to "use up" the cold start before I get into the joint. You can sort of see it in the 1st pic. Ive been beveling the thicker plate to get the metal thickness closer to the 1/3" rings.
Reply:Originally Posted by Edward BilI am pushing the wire. Smut is for some other reason.  Does the 4943 or 5356 bond well enough with 5052? Thanks abec and shovelon for the specific help. With my clarifications, any other factors that could be in the way?
Reply:Originally Posted by HT2-4956Judging by all that black smut I see it looks like you're probably pulling the puddle.   You need to push it.
Reply:the presence of black smut on alu welds is an indication that the weld is lacking in cleaning which could be cuased by direction of weld, lack of sheilding gas, dirty material, and machine setupHigh Octane Welding
Reply:Okay. 5356 .047 26V 500ws 40psi. Pull method. not much rocking, just keeping the angle even in the 1/2 second I have on the joint. seems to have a slightly better root. What do y'all think?  Also, just for scale, there are 20 fins and 15 rings, so 300 points of connection like this one.  Total object weight should be around 900lbs. Hence the concern for good penetration.  We probably have a bundle of sticks kind of strengthening here, so no point alone will make or break it. We have an engineer, just want some better welders than me to have a look. Last edited by Edward Bil; 09-24-2014 at 03:40 PM.Reason: Added thoughts
Reply:Here's a pretty informative article on aluminum welding smut.http://www.thefabricator.com/article...mize-weld-smut
Reply:Originally Posted by HT2-4956Here's a pretty informative article on aluminum welding smut.http://www.thefabricator.com/article...mize-weld-smut
Reply:Agreed. Thanks HT.  By that I'd guess my smut is from the fact that this is 5356 and my gas was too low. I'm not going so far as scrubbing these with acetone, but the workspace is pretty clean otherwise.
Reply:Originally Posted by Edward BilOkay. 5356 .047 26V 500ws 40psi. Pull method. not much rocking, just keeping the angle even in the 1/2 second I have on the joint. seems to have a slightly better root. What do y'all think?  Also, just for scale, there are 20 fins and 15 rings, so 300 points of connection like this one.  Total object weight should be around 900lbs. Hence the concern for good penetration.  We probably have a bundle of sticks kind of strengthening here, so no point alone will make or break it. We have an engineer, just want some better welders than me to have a look.
Reply:Bill,I just checked this chart   http://www.alcotec.com/us/en/support...tion-Chart.pdf  and it looks to me that 5356 is a pretty good choice for welding on 5052 base material.
Reply:That looks better to me. Can you wrap around the corners at the terminitions?Probably not with any skill, but I'm planning on hitting them with a pass from the other side, just to seal the joint from elements if nothing else. Wanted to leave them open for the purpose of showing some small version of a cross-section for you guys. I expect lots of post work cleaning these up, just need them to bond, much less concerned with pretty welds.
Reply:Ed,I see what's coming for you as you try and put those remaining fins in and it's not looking pretty.  I honestly don't how you're ever going to get a spool gun in there for most of it.   I can't see where even a regular MIG gun would gain you much advantage.   I think you might be hard up against one of those situations where the designer of the part doesn't understand the difference between theory and what's actually possible very well.   I wish I had an answer for you but I just can't think of one at this point.  I don't know if it will make you feel any better about your situation, but for what it's worth I don't think that even the best among us here would have much chance at getting good welds on that.   Maybe if you told us more about what that assembly is for (and what kind of environment it will operate in) some one might have an idea.   The answer might involve getting rid of welding that joint all together.  For instance, some form of mechanical lock or epoxy adhesive.Last edited by HT2-4956; 09-25-2014 at 10:50 AM.
Reply:Well I fabricate for an artist, so theory and reality rarely are in the same room. It is a basket like structure sticking up in the air about 22ft. It only needs to support its own weight. It will be in Albuquerque looking pretty and doing nothing functional.
Reply:Originally Posted by Edward BilWell I fabricate for an artist, so theory and reality rarely are in the same room. It is a basket like structure sticking up in the air about 22ft. It only needs to support its own weight. It will be in Albuquerque looking pretty and doing nothing functional.
Reply:Locktite makes amazing adhesive nowadays. I think if got a little more stickout (the distance between the contact tip and the work) you would see an improvement. For short welds with Aluminum you want a spray transfer with a long arc.  Make sure you make use of the two stage trigger, flooding the area for several moment with gas before you start the arc. You will probably need to wipe the weld down to remove some black, but it should be light if all is well.Constant Current Weldor.