[human_glue_gun]

Hi! I’ve been welding for a sign shop for a little over a month now. I started out welding thick aluminum, I beams, but now I’m welding brackets onto 3/16” aluminum sheet. I’m not getting a ton of heat marks on the opposite side, but would love to eliminate all marks on the opposite side of at all possible. The signs come to me pre-sanded, I try not to scratch them on the table and I have been asked to only do a series of tacks to hold the brackets on because this shop has had issues with previous welders burning through to the front of the sign like crazy. Our signs are painted or covered in vinyl, so any marks have to be sanded off. The shop is satisfied with my work but I want to speed things up if possible, and the guy who does all the sanding work helps me out a lot with lifting heavy objects (I’m a girl) and I would like to make his life easier.

Settings: welding on 3/16” thick aluminum at 160 amps, 35-40% cleaning, 1/8” 1.5% lanthanated tungsten, 1/8” 4043 filler, 120HZ(pretty sure, I’ll double check if it matters), Everlast 325EXT

Question: trying to see if it is possible to eliminate all heat marks on front of sign

I’ll add photos when I am home from work, I’m on mobile right now, but the signs themselves are large (64”-72” long) almost square.

[cj737]

Use designated, clean stainless steel wire brushes promptly after welding. Should clean up your welded area without tearing up the aluminum. Or use ScotchBrite pads if you find the light scratches unpleasant.

[Spartan]

Yeah, it's tough avoiding heat marks/scaling on the opposing sides of most metals, especially thinner stock. Planning to lightly dress it afterwards is probably best in this situation, but may also be worth while to experiment with clamping chill bars on that opposing side to help draw away some of the heat from that opposing surface and keep it cleaner. Chill bars may seem a bit counter-intuitive for aluminum, but might be worth a trial to see how it does.

[VA-Sawyer]

I'll bet it takes time to get a good puddle going with those settings. The time you spend getting a good puddle, is also heating up the work. One thousand one, one thousand two. If the puddle isn't ready, you don't have enough heat at the torch.

I would set max Amps to 225 or even 250. Get a good puddle, then back off on the pedal. I would also reduce the cleaning action to 20-25%. This will help put more heat into the weld. If you can't get a fluid puddle at 25% on new metal, then it needs to be better prepped.

I know it sounds backwards, but more heat at the torch allows you to weld a bead with less total heat going into the work. You get in, weld a short bead, and get out, before the heat spreads through the plate. Move to a different bracket, and do it again. Keep moving from bracket to bracket, doing short beads, till they are done. If need be, take a short break after each round, to allow cooling.

[human_glue_gun]

Yeah, it's tough avoiding heat marks/scaling on the opposing sides of most metals, especially thinner stock. Planning to lightly dress it afterwards is probably best in this situation, but may also be worth while to experiment with clamping chill bars on that opposing side to help draw away some of the heat from that opposing surface and keep it cleaner. Chill bars may seem a bit counter-intuitive for aluminum, but might be worth a trial to see how it does.

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Here are some images of what I am dealing with now that I can add them. They may or may not be helpful. The second image is the front of one of the signs, where you can see the bit of heat mark. I had definitely thought about some method to use chill bars and think it is a good idea! Would just have to figure out a way to keep everything perfectly flat because I have to clamp it all pretty tight. I am only able to tack on one side of the brackets because they are fitting around I beams, and the brackets tend to pull outward with the heat, so I clamp them tight around a piece of tubing that is the same width as the beams. I tack 2.5" apart, and I skip over every other tack for the first round through, then go back and add the tacks in between after things have had a bit to cool. The big piece of channel that is clamped across the middle is to hold the bracket flush against the sign in the middle because I cannot fit a clamp there. I have a long piece of tubing across the brackets clamped on either end to try to hold the bracket down as uniformly as possible. Considered welding a jig but this seems to work well, my supervisor is very happy with the fit up.

Thanks so much for your help! Going to think about how to make this work because for sure will be doing a lot more of these at this job.

[human_glue_gun]

I'll bet it takes time to get a good puddle going with those settings. The time you spend getting a good puddle, is also heating up the work. One thousand one, one thousand two. If the puddle isn't ready, you don't have enough heat at the torch.

I would set max Amps to 225 or even 250. Get a good puddle, then back off on the pedal. I would also reduce the cleaning action to 20-25%. This will help put more heat into the weld. If you can't get a fluid puddle at 25% on new metal, then it needs to be better prepped.

I know it sounds backwards, but more heat at the torch allows you to weld a bead with less total heat going into the work. You get in, weld a short bead, and get out, before the heat spreads through the plate. Move to a different bracket, and do it again. Keep moving from bracket to bracket, doing short beads, till they are done. If need be, take a short break after each round, to allow cooling.

I considered something like this but wasn't sure! I went up to 170 because that was the max recommended on the miller calculator, but I know that the calculator isn't always correct.170 didn't really help, may have made it a tiny bit worse. I'll probably test your amperage suggestion a bit on some scrap of the same thickness and see how it does (I just can't wreck a single one of these signs if I do burn through too much). I have been spreading out my welds to help with heat input. I'm only dabbing my filler 1-3 times, they're just tacks, I weld every 2.5", and I skip every other tack the first time through, then go back and weld the spots I skipped to allow some of the heat to dissipate. I do notice that it takes a second to puddle, longer than I would like. I think going down to 25% would be totally fine, that was where I was at before when welding I beams because I learned lowering the cleaning would help with penetration. Same cleaning method, acetone, seems to do fine. The metal is already pretty clean by the time it comes to me. Thank you for the help, will definitely trying cranking it higher and see if it helps.

[Spartan]

I'll bet it takes time to get a good puddle going with those settings. The time you spend getting a good puddle, is also heating up the work. One thousand one, one thousand two. If the puddle isn't ready, you don't have enough heat at the torch.

I would set max Amps to 225 or even 250. Get a good puddle, then back off on the pedal. I would also reduce the cleaning action to 20-25%. This will help put more heat into the weld. If you can't get a fluid puddle at 25% on new metal, then it needs to be better prepped.

I know it sounds backwards, but more heat at the torch allows you to weld a bead with less total heat going into the work. You get in, weld a short bead, and get out, before the heat spreads through the plate. Move to a different bracket, and do it again. Keep moving from bracket to bracket, doing short beads, till they are done. If need be, take a short break after each round, to allow cooling.

I considered something like this but wasn't sure! I went up to 170 because that was the max recommended on the miller calculator, but I know that the calculator isn't always correct.170 didn't really help, may have made it a tiny bit worse. I'll probably test your amperage suggestion a bit on some scrap of the same thickness and see how it does (I just can't wreck a single one of these signs if I do burn through too much). I have been spreading out my welds to help with heat input. I'm only dabbing my filler 1-3 times, they're just tacks, I weld every 2.5", and I skip every other tack the first time through, then go back and weld the spots I skipped to allow some of the heat to dissipate. I do notice that it takes a second to puddle, longer than I would like. I think going down to 25% would be totally fine, that was where I was at before when welding I beams because I learned lowering the cleaning would help with penetration. Same cleaning method, acetone, seems to do fine. The metal is already pretty clean by the time it comes to me. Thank you for the help, will definitely trying cranking it higher and see if it helps.

The tell-tale sign that you're about to burn through is the puddle starting to sink or slump down into the base metal. When you see that starting to happen, even slightly, you need to react quickly and taper out fast or cut the arc right away if you can and just let the part cool. It's much easier to spot on steels than it is on AL, but you can prevent it on either when you know what to look for.

Recommend getting some scrap metal and intentionally burning through it (and then preventing it) to train your eye and your reflexes. Do it over and over again, and it will become second nature to quickly react when you see the signs that it is about to happen.

[VA-Sawyer]

She can't afford to wait for the sign. (No pun intended) Even if she starts to taper off just before the sign appears, she will have a heat mark on the other side.

Hit it hard and get a puddle fast. Then dab, move, back off the pedal a bit. Dab, move, back off a bit more, dab, dab, start tapering off as you move it back towards the first dab. Wait for the post flow. Total arc time of maybe 3 or 4 seconds. Now carefully check the temp where you plan on making your next weld. If it is too hot to hold a bare hand on, move your next weld further up the line.

3/16 is 187 thousandths if my brain is still working. Steel is 1 Amp per thousandth, aluminum is a bit more. Call it 200 Amps for a constant weld current. On cool aluminum, the starting current needs to be higher. After giving it a bit more thought, I'm moving my initial suggestion from 225-250 up towards 275 Amps starting current. Think of it as doing a flash tack with 3 or 4 dabs tossed in. You want to have your first dab done, before the other side of the plate knows you lit an arc.

[tweake]

I considered something like this but wasn't sure! I went up to 170 because that was the max recommended on the miller calculator, but I know that the calculator isn't always correct.

another person falls victim to the incorrect online miller aluminium calculator.
i have millers paper chart here and it says 210-240 amps with a 1/8 filler rod for 3/16" aluminium.
i would be inclined to run hotter for the start.

also to reduce heat pulse can come in real handy.

[BillE.Dee]

I was wondering about pulse BUT the man from down under beat me to it. Any possibility of using a dot (wack it quickly, then move) to hold things together and then coming back with pulse to expand after there is heat evident in the whole build? It just may be a bit tricky to use pulse all the way thru...start to finish...AYE ??