First aluminum welds- nothing to write home about

[DaveO]

I thought I'd try the "pad" that Jody recommends, but it quickly became clear that I need to RTFM some more (and get more practice). Eventually I got around to some lap joints. What is the cause of the sooty looking coating on lap #3 at the bottom of the photo?

For the lap joints I scored a piece of 1/8" x 3" flat and broke off 1 x 3 pieces (roughly). The surfaces you see are all the underside of another weld, and all those pieces went from "shiny" aluminum to the brown discoloration. Is that overheating the base material? Controlling heat was a problem. The puddle would turn from fluid to ropy, and I was trying to recognize a pattern for what was causing it.

[sportbike]

Skip the joints until you can push a puddle and do some bead on plate welds.

The black soot is likely caused by you touching the tungsten to the aluminum puddle.

Did you clean the metal before starting to weld? It doesn't really look like you did. Try starting off with a flap wheel or other abrasive disc cleaning on the aluminum.

[sportbike]

What settings on the machine, what tungsten and argon flow?

Was the ground clamp clamped to the workpiece?



Once you get better, you can get away without cleaning the material as much and with more out of position and unusual joints.

[DaveO]

Argh, I thought shiny aluminum like that was clean "automatically". I wiped it down with acetone and the rag turned black, and I thought that was enough- too funny.

3/32" 2% lanth, 15 lph, 1/4" stickout, and I was adjusting weld amps looking for a sweet spot. I clamped the ground directly to that tread plate, and the lap joints laid on top of that plate. Thanks for your info- lots more study and practice for me.

[sportbike]

Try cleaning it first (abrasive)

Also, you may find better results with something closer to 6-8lph on the argon flow.

The regulator that comes with the welders (mine at least) is kind of crappy and the pressure regulation is poor. I usually tap the pedal to get the high pressure burst out of the way just before starting to weld. Probably not an issue for what you are doing.

When you use filler, try to keep it inside the shielding area as well, otherwise it can start to oxidize.

[DaveO]

Gotcha, thanks. I'm annoyed that I dipped the tungsten so frequently.

[Rambozo]

If you do tip the tungsten, resist the urge to just keep going. Stop and swap tungstens or grid off the aluminum coating on the one you dipped. It will make a big difference. Also grind or brush off the area of the plate where it went poof, and remove all the black soot, or just move to a fresh area. Cleaning action will break up oxides, but not much more. If it doesn't look clean, it isn't. Aluminum and stainless both have to be squeaky clean to get great welds. Do the grind/brush, then the wipe down with acetone. Also if your rods have been sitting around give them a wipe, too. If the rag comes back dirty, do again until it doesn't. Aluminum oxidizes up instantly after you grind it. The cleaning action will take care of that, but anything more, you have to remove before you start.

Any idea of what your amperage was? Use a larger cup than you do for steel, and I would back down the flow like Sportbike said. A #8 will need about 7 lpm or so, more as you get bigger. I think tapping the pedal is a must or dial in some preflow. Either will do the same thing. You want to hear the argon flow settle down before the arc starts. How long that takes will depend on your setup. Usually just a second or so, but it's a sound thing, you can hear when the blast is gone and the flow is steady.

Maybe use a little less stickout, so you can have the edge of the cup touch the work before the tungsten hits the puddle. That will help guide your height and keep the dipping down. Be sure to have a good prop and arrange yourself to be able to hold the torch steady.

[DaveO]

I appreciate the critique and the advice- thanks. I changed amperage around from about 100 to 120. I was following a calculator when I dialed into 15 lph- unless I got that detail badly wrong. I had a #7 cup on the torch. I was able to prop firmly enough but I felt like I was fighting the torch the whole time because the twist in the cable cover, and possibly the cold weather, made the torch want to resume a particular attitude that match the weld.

On a positive note I felt like I learned a lot just from observation, even though the results were nothing. At one point I saw the cleaning action taking place on one side of the arc, for instance, figured there was a problem with the tungsten, and the problem resolved when I changed electrodes.

[piopio]

im only at this a few months,so no expert....
but grind a few tungstens at a time,much less frustrating when you dip.
the torch leads can be a pain,but spend as long as it takes to get it comfy in your hand,
then do a dry run of the weld,making sure where your hand/torch ends up at the finish of the weld is not at a stretch

[Jason]

The calculator might be measured in cfh which would then be about right to the 7lph.

[jakeru]

lph??? You mean lpm, right? (If so, I agree to try 7 lpm, because 14 lpm will likely cause turbulence and draft in air with that size cup.)

It looks like you've got some workpiece overheating going on with the small coupons on the right pics, with the heat running away. Counter-intuitively, the cause is using not enough amps (and traveling too slow.) Start with those small coupons close to room temp (not pre-heated) and move a little quicker with them to "outrun" the heat.

The heat build-up didn't seem as much of a problem with the larger piece on the left pic. It looked a little cleaner as well. I prefer welding aluminum without the largest cup size possible... I prefer about a #6, or even a #5 works very well. Gas lens is not very important on aluminum, either.

Practice getting a good torch angle, so that your filler rod doesn't melt before getting it to the puddle. Learn to recognize the puddle, and consistently and precisely adding filler, and maintaining proper torch angle. When you feel ready for a change, try the flat coupon joining (laps or butt welds with tight fitup are good. Tack both ends first, then weld the middle.) You could even focus your practice on just making good tack welds (it may not be easy.) Best tack weld needs to be not lager than your final weld bead is going to be (so you can make it disappear afterwards.)

Keep at it... Doesn't look bad for a first go.

[fdcmiami]

Argh, I thought shiny aluminum like that was clean "automatically". I wiped it down with acetone and the rag turned black, and I thought that was enough- too funny.

3/32" 2% lanth, 15 lph, 1/4" stickout, and I was adjusting weld amps looking for a sweet spot. I clamped the ground directly to that tread plate, and the lap joints laid on top of that plate. Thanks for your info- lots more study and practice for me.

dave, get rid of the treadplate and get your hands on some decent sheet stock or extrusion. i guarantee this will help you more than you know.

[Jason]

lph??? You mean lpm, right? (If so, I agree to try 7 lpm, because 14 lpm will likely cause turbulence and draft in air with that size cup.)

Yes that is what I meant. Thanks.

[DaveO]

"turbulence and draft in air with that size cup" Too funny, it's turned into an episode of "how many details can I get wrong?" I can't get out of my own way! I went back and checked the welding calculator and sure enough it said 17 cfh. So using the rough "divide by 2" conversion would have put me in the ball park y'all are suggesting, and I'd have a couple hundred pounds more argon left. Argh!

Thanks to all for the commentary and suggestions. Another question: FDC, (or anyone), why does tread plate make a difference? Is it the periodic variations in thickness?