Ali GMAW - defect rates - spray, pulse

Posted in s.ej.w. primarily, due to content; but not much activity
there, so putting plea here...
Hi
Plea for real experience information.
Thicker Ali at above about 130A.
Probably wire-feed-speed at or above 10m/min (394ipm)
Thinking of marine-grade 5000-series Al-Mg, but experience of other
grades would apply regarding this question.
For welds, compare / contrast:
* spray-transfer/smooth-run
^
v
* Pulse-mode/stepped-progression
Or any comparison of spray/Pulse modes and of smooth/stepping
progression.
Flaw and defect rates, please.
This would be by radiography (x-ray) and mechanical test (strength
alone will reveal everything important about Ali?).
Here in UK we have an orthodoxy about which process / approach must be
used.
Defect rates are /
can-be high.
Which surely simply cannot be the case universally???
Unfortunately I have not been able to test the welds I trust the most.
Thanks in advance,
Rich Smith
Reply to
Richard Smith
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Posted in s.ej.w. primarily, due to content; but not much activity there, so putting plea here...
Hi Plea for real experience information....
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I'm better at Googling than welding. Here's some hands-on experience on material prep that I didn't hear in welding class:
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Reply to
Jim Wilkins
They sound good and talk sense. All they mention are pre-requisites. However - they talk of GTAW (TIG), not GMAW. GMAW you have to use for boat *building*. Much more productive when you have long weld runs. GTAW you'd use for making an Ali ladder - or doing a patch repair - because GMAW becomes unworkable for short runs and GTAW has no such limitation. You can adapt a lot more with GTAW. GMAW you pull trigger and go - and you are commited to a run at that condition.
Reply to
Richard Smith
They sound good and talk sense. All they mention are pre-requisites. However - they talk of GTAW (TIG), not GMAW. GMAW you have to use for boat *building*. Much more productive when you have long weld runs. GTAW you'd use for making an Ali ladder - or doing a patch repair - because GMAW becomes unworkable for short runs and GTAW has no such limitation. You can adapt a lot more with GTAW. GMAW you pull trigger and go - and you are commited to a run at that condition.
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I took night school classes in acetylene, stick, GTAW and GMAW welding and became able to pass a bend-double test with 7018, fabricate a log splitter, a sawmill and a hydraulic bucket loader for my tractor and patch rust holes in my vehicles. I didn't practice out-of-position other than vertical because I make fairly small things I can lift and turn, and I didn't do well with TIG or MIG on aluminum. I soldered electronics for a living which is also about making molten metal flow where you want it to, and not where you don't.
The beam I was asking about became a hand-portable (in pieces) overhead gantry hoist 16' long with a tested 1 ton capacity. It's about the biggest thing I expect to weld on.
Tell me more about short runs with GMAW. Auto body repair consists of tack welding a sheet steel patch loosely fitted into the cleaned-up rust hole, then removing the clamps or magnets and filling between the tacks in burst short enough to minimize heat distortion and avoid melting through. After grinding the weld flush there will be (for me) voids and pinholes to fill in with weld metal. I've practiced filling in a coin-sized hole in sheet metal.
Reply to
Jim Wilkins
Real world Experience. Almost none.
I said "almost". I did some 3/8 (9.5mm) 5052 with full bevels, and massive preheat with a torch using a Miller 212 with a spool gun. It looked terrible. I ground out and re-welded portions of it several times. I made it "look" ok with a flap disc. It didn't break. I don't recall the settings. I used what it said on the flip card on my welder, and found a little more wire than that worked better.
I've tried welding 1/2"(12.7mm) 6061 a couple times and it was pretty much terrible no matter what I did.
I had heard you could go with an Argon Helium mix and get better results, but I have never done it.
Reply to
Bob La Londe
6000-series (extrudable alloys) kicks the arc off itself. Welding 6000-series to 5000-series is worse... Familiar experience (?).
I've only used pure Ar (argon). It works fine.
I've had Ali-GMAW which look just like a steel T-fillet weld but matt-silver Ali appearance.
However - my first couple of days were "unpromising". It was only the raging covid19 pandemic and "lockdowns" which had me persevered-with until I got the other side of "the learning curve" hump.
Reply to
Richard Smith
I found 1/4" (6.35mm) would allow me to wallow around like I was welding steel. 1/8" to 1/4" seemed to be the butter zone for 5052 for me. I was successful with 5052 as thin as .080" (the boat hasn't sunk yet) and I managed to stick .043" once, but thinner aluminum isn't as easy as thinner steel. I have to go crazy fast and still only run short beads. I never tried "stacking tacks" with thin aluminum like I have with thin steel.
Didn't we have this same conversation last year?
The +He is recommended for thicker aluminum or so I have heard. I've got a lot of scrap 1/2" 6061 flat bar from bad cuts and bad decisions machining. It would be nice if I could weld it together and make stuff out of it. It wouldn't bother me in the least if one side still showed the failed mold cavities that turned it into scrap. In fact the tool racks on my CNC mills are made from such scrap.
Reply to
Bob La Londe
Yes this is a repeated plea. Maybe made earlier this year.
With
* the covid19 pandemic recent and a counter-useful "lockdown" (it would have had nett negative consequences) only just averted - the Government passed in Parliament another set of restrictions but desisted in the face of all reality
*
the Ukraine war had kicked-off and negative economic consequences to Europe figuratively flashed in bright neon signage
* I had to walk out of an Ali welding job, talking over the foreman trying to describe the next job he wanted me to do, saying "I just want out, immediately" (I'd just completed a safety-critical job against all the mounting odds, protecting those I worked with, as a "last push")
I was exhausted and confused.
I've had other things to do since - taken care of. But never resolved these questions. They lingered in the background. Perturbing me what I contemplated returning to weldign work.
That was the space I was in when I wrote that plea only a couple of days ago.
But that as a process served a purpose. Because...
Today I woke up bright with a fresh head on, pumped wieghts in the garden, then read the Lincoln advice on Ali-GMAW.
That's their well-known c8100.pdf "Aluminum GMAW Gas Metal Arc Welding for Aluminum Guide"
Coming back after so much experience, I read and understand so vastly much more of what is there. I *
think I see* many answers to my questions. I see answers in what I have already read, but didn't have the practical experience to assimilate then when going into the Ali welding jobs.
I still would like to hear from those with real-world streetwise experience - who have done Ali-GMAW welding including testing like radiography, mechanicals (tensiles), bends, carefully considered and controlled "sledgehammer" break tests on test welds, etc.
Best wishes, Rich Smith
Reply to
Richard Smith
I still would like to hear from those with real-world streetwise experience - who have done Ali-GMAW welding including testing like radiography, mechanicals (tensiles), bends, carefully considered and controlled "sledgehammer" break tests on test welds, etc.
Best wishes, Rich Smith
---------------------------
A former neighbor is a certified pipe welder who specializes in alumin(i)um GMAW. If I see him I'll ask if he is willing to chat about it.
Reply to
Jim Wilkins
That would be so appreciated.
Reply to
Richard Smith
P.S. I have two boat projects (full builds, not repairs) in the works. I have the metal on hand for one. Do you want to hear about all the dropout holes I blow in the sheet? LOL.
I may be pushing my limit. The first boat is designed to be a light shallow runner with only .080 hull and bulkheads. I've mig welded .080 before, but it was tedious at best with lots of double/repair work. I imagine it will be good practice for the second one and the one I really want to do. A bit larger (longer wider) faster shallow water runner with a .125 hull.
Reply to
Bob La Londe
Completely different domain from where my cry of continuing pain comes from.
Below 4mm - certainly 3mm - the benefit of Pulse GMAW is unmissable.
* >= 10m/min - spray at about 24-ish volts * < 10m/min - pulse
(/ 10e3 25.4) ;; 393.7007874015748
BTW I'd say always think wire-feed-speed with GMAW, because that is interchangeable and transportable across machines and workplaces. (if you set an all-singing all-dancing machine to "8mm Al", what that means will never be known to you and if you "calibrate" how you visualise your welds according to that, you will have nothing when you move to another job). What is the same with my "cry of pain" message - the Laws of the Universe make wire-feed-speed with GMAW the central measure which is impossible to circumvent. What I mean is, "snake-oil salespersons" you can have this, that AND the other, but Laws like heat conductivity, latent heat of fusion, the electrical ionisation of argon, etc., mean this is 100% drivel.
Anyway, digressions...
At these lower thicknesses where the wire-feed-speed falls below 10m/min (394ipm), do switch to "Pulse", which will work brilliantly, and I haven't met a Pulse-GMAW machine yet where the "Synergic" single-knob control doesn't give you an ideal condition (no "my 'magic' settings").
Now, that is in an industrial setting with top-brand welding machines costing thousands of US$ equivalent. This would be talking about a workshop environment where everything is 3-phase power.
So what I am saying might come from a different world. But putting 3mm (1/8") end-plates capping extruded 4mm and 5mm wall rectangular hollow sections with outside-corner welds (very low heat demand) - easy money for me switching to Pulse-GMAW.
Thanks for all help, and I just want to be helpful in return.
Best wishes, Rich Smith
Reply to
Richard Smith
If only I had a pulse MIG. The Miller 212 is straight DC manual set. My best results came from lots of tacs, and then random stitch and fill with plenty of cool down. Since it welds best with brushing and chemical cleaning just minutes before welding cool down is part of the process. I did pickup an AC DC pulse TIG a while back, but my abilities with it are much worse as of yet.
I don't know if I told the story about how this machine sucked for years welding steel with gas, but now its pretty decent. I actually ran this machine with flux core for steel those years because it sucked so bad with gas.
Reply to
Bob La Londe
Can't fault you for perseverance! :-) Best wishes,
Reply to
Richard Smith
I am not a welder. I am sure that's clear. The thing is everybody told me how easy MIG was. I had a little flux core Horrible Fright wire feeder, but it was pretty miserable. Even after cutting a giant hole in the case and adding a cooling fan it still only made about 1-1/2 to 2 inches (35-51mm) of weld before going unstable. I finally broke down and bought the Miller 212 some years back. All the wannabe pros at the time were pooping on auto set machines so I went for a manual set machine. It still was not cheap. After a huge learning curve I was able to hot glue aluminum together with the spool gun, but it absolutely sucked running GMAW with the regular stinger. I could swap the leads (have to open the cover to do that) and run unshielded flux core all day long (and its easier for out of position welding), but it absolutely SUCKED in the most unpleasant way trying to MIG weld with gas. Finally one day I decided I was going to do what I was best at. Troubleshooting. (licensed communication contractor)
I walked into the back shop and told myself I was going to figure out what was wrong with the stupid machine or destroy it trying. I powered it up, put my hand in front of the stinger and pulled the trigger. I felt gas. I saw the wire feeding. I pulled the hood, put my hand next to the electrode, and pulled the trigger again. I saw the wire feeding, but I didn't feel any gas. I ran my hand all around the nozzle and felt gas coming out of the tip, but nowhere else. That didn't make any sense to me. If that's where the gas comes from what is the point of the nozzle. I didn't really know what I was looking at or what the parts were called, but I knew something didn't look right. After some image searching online I found a picture of the parts for other welding stingers. One part caught my attention. It was called a gas diffuser. The thing is all the ones I saw on-line had holes in them... I took pictures of the pieces, and posted them on the Miller Welds Forums asking, "What's Wrong With This Picture?" A few people got close, but nobody got it. Then I didn't feel quite so bad. When I spilled the beans somebody with Miller sent me a private message asking for my address so they could send me a parts kit.
A few people tried to claim it was a used machine or a dealer restocked machine or make some other excuse. Nope. It was purchased brand new from Indiana Oxygen and drop shipped to me directly from Miller. Dual solenoid, dual bottle rack, dual stinger setup for GMAW steel or aluminum. Just swap singers.
I was really pleased after all those years I could finally start to learn to MIG weld. I was also really frustrated, because I allowed self doubt about my own abilities to over ride common sense. I thought all that time there was something wrong with me when there was actually something wrong with the machine. Something just snapped inside and told me, "IT'S NOT YOU BOB!"
I remember trying to get help, and everybody seemed to have the same attitude, "MIG welding is so easy even lower primates can do it. Just get out there and practice." I'm not going to turn a tree shrew loose in my shop with a MIG welder, but horizontal hot gluing steel together isn't to bad now. I do get frustrated when I try to vertical or overhead and forget its not flux core, but it finally works the way it is supposed to.
Reply to
Bob La Londe
I am not a welder. I am sure that's clear. The thing is everybody told me how easy MIG was. ...
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I just couldn't get thin sheet steel to weld until I tried pushing instead of pulling, then a nice thin flat puddle spread out neatly across the joint without burning through.
I never did learn MIG on aluminum, but I could manage with TIG on the little welding I needed for industrial robots. Welding the waterproof housing was a big enough job to contract out.
Reply to
Jim Wilkins
Bob - you describe what sounds like the pummeling my mind is having. A point I saw myself and someone said the next day - if Ali-GMAW is such a problem here; don't do it. There's other welding and other jobs...
Reply to
Richard Smith
I seem to recall earlier in this thread you said it was "thick" aluminum. As I made clear I am no expert, but aluminum is a massive heat sink that melts and drops out at lower temperatures than steel welders are used to, and there is no big color change to warn you as to the temperature of the metal. Thin metal falls out almost without warning, and thick metal steals your heat and spreads it across the entire work piece to dissipate with little affect. I think this means the skills are harder to learn and take more practice. No clear visual indicators and harder to control heat input.
The thickest aluminum I have ever MIG/GMAW welded successfully (that is arguable) was 3/8 inch (9.5mm). I did it by beveling (thinning the edge), and preheating with a rosebud. I literally clamped the rosebud to the structure so it was keeping the entire piece hot from the back side while I was welding. I had the welder cranked up, pretty fast wire speed, with 0.035 wire. It was crazy and dangerous to me. Cleaning was mechanical only for obvious reasons. Straight argon at about 30CFH inside a building with one door open to minimize air flow through the building. That's all basic stuff you already know.
I have heard that the addition of Helium is the magic sauce that gives you better penetration with thick aluminum.
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*** "The typical gas you will need to weld Aluminum is 100% Argon gas.
If you normally MIG weld mild steel using C25 gas, don’t worry you can use the same gas hose and your regulator designed for Argon gas.
Welding thicker pieces of Aluminum 1/4 inch to 1/2 inch then you may well find a mix of Argon and Helium better for deeper penetration." ***
I've seen numbers as low as 2% and as high as 25% helium stated. The article linked above says 25%. In this article linked below they say 25% to as much a 75% helium, but they also specify 1/2 inch or thicker.
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*** "However, MIG welding aluminum works best with a 100% argon shielding gas.
It involves using the spray transfer process with a flow rate of 20 to 30 cubic feet per hour for proper gas coverage. But if you are planing on welding thicker pieces of aluminum, 1/2” or more, 25% to 75% helium should be added for deeper penetration to be achieved.
Basically, 100% argon is used to keep the weld clean and free from oxidation. Helium is used to increase penetration ability when welding aluminum." ***
I seem to recall you mentioning that other gases or gas mixes you do not already have on hand are resisted by management. I can not help you there.
Getting back to the basics. Welding thick metal takes a lot of power. I must assume you have industrial machines much larger than the job shop size machines I own, so that should not be an issue, however there is another basic. See if you can talk to a company rep for the brand of machines you are running. They may very well be able to help you with a process for your applications. When I searched for conversations about "MIG welding thick aluminum," that was one of the responses I saw on the Miller Welds forums. Talk to the company rep.
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*** "Although the forum is a great place to get tips and advice you should also call your local Miller rep to come in and help you get things running correctly."
"And you may want Helium in your Argon mix for heavier parts. But I don't know until you try it. Post some pics too..."
More... *
**
From what I have read you will need MORE POWER, THICKER FILLER, and HELIUM for additional penetration for thick aluminum. That and more practice than you needed to learn any of the steel welding processes you already know.
I don't want to come off as the hack trying to teach the expert. I am a hack, and in many types of welding you are most certainly the expert. I'm just trying to help you get on track to learn it and become the expert in one more. I mean really. When I need to do something like that myself I want to be able to just ask you and have you tell me the mystical secret recipe.
Reply to
Bob La Londe
That was for >>>steel<<<.
That's right. Yes, it is a continuing big problem here. There is an orthodoxy for GMAW shielding gas compositions for steel here which doesn't seem to exist anywhere else in the World. It is technically "just wrong!".
On a plus side - I once saw a penetration bead through 8mm steel :-) ! That was an 8mm wall pipe onto a 25mm steel baseplate - presenting a fillet weld - with the component being rotated. Much quicker to have two welders, one on the torch and the other rotating the piece on a little table. Chasing "spray" at higher Amps, we were up at about 40V, as it never really broke into "spray". This is a fillet weld - you don't need penetration. You seek fusion to the fillet corner. No benefit in weld penetration to the opposite side of the World...
When you get one of these orthodoxies, the human dynamic is that you never get to try anything else. You put in a special order for a different gas: they specially deliver three bottles of the same gas the orthodoxy demands for which you have plenty of bottles, with an explanation that they had to "correct" (sic.) your order. Etc.
Kind of - you are locked into madness, and there is no explaining madness.
I'm suspecting the same with my Ali question. The conditions I find work well, not a problem to be found, are the ones the Lincoln Foundation recommend, by the way, just to strongly suggest I am standing on sound ground.
Reply to
Richard Smith
As best I can comment - yes, excellent article and you are well-served by reading it.
The Ar-He gas I can't comment, because if it's expensive there in the North America it's very very expensive here.
His wire-feed-speed is exactly where I would expect it to be (he uses 560ipm). His voltage is reporting a bit higher than I would have expected - but Volts is not a physically conserved quantity like Amps (you can measure Amps anywhere in the circuit). With the accuracy of voltmeters and maybe a bit more voltage drop between power-unit and the tip of the torch, it's probably one and the same voltage (I'd be looking at about 24V, if memory serves me rightly).
I am saddened that he is getting moments of instability, with welds in that area which are not what he'd be most proud of. Good cleaning - wire brushing just before welding - is always a first step in such troubleshooting. My max. Ali thickness yet is 1/2inch (12mm). He's going up to 1inch (25mm). Beyond my experience - don't know if there's anything "up there" I don't know about re. "spray" arc performance.
You'd have about 6kW of electrical power in the arc (250A*24V), so power draw "at the wall" would be something like 12kW. So yes, these are industrial powers.
I did go for a weld test at a stainless steel place where they used an Ar-He-O2 mix, and it welded well, and I suspect the He did have some good effect.
Back to Ali...
I wasn't wanting for anything with 100%Ar at 1/2" (12mm) thickness. Above that - won't comment on what I haven't experienced.
Reply to
Richard Smith

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