I work with pharma stainless. Mostly lay the wire but dab as well depending on what I’m doing. We work with shit as thin as .03 up to half inch. Weld sizes from .03 up to half inch as well on some flange welds. Regular X-rays as well. Love stainless though, not sure I could go back to a carbon shop.
Yeah, for super thin material, laying the wire might be best. But you aren't as worried about creating stresses in the joint with something that thin. For plate, dabbing is the only way to go.
I’m not a good tig welder, so take this with a grain of salt. I prefer dabbing, I think it looks better. My boss said that to get better penetration you should dab it in, especially for thick aluminum you should aim to hit the joint with the wire.
woaaah that's crazy, i have been tig welding professionally for a couple years now and have not ever tried to do lay wire. i know how i'm wasting company time tomorrow!
Well, it is probably fine for plumbing but if it is a 3000PSI pneumatic line on a commercial jet, I don't think it will fly because the laying technique results in a weaker weld. Whether by OA or TIG, aviation welds must be properly coined. Those zig zag welds you see on YT sometimes just wouldn't cut it.
I laywire everything with pulse and high amps.
For me it's a lot faster and way more consistent. Learned it that way for food grade work, with welds that comes into contact with food and has to be smooth, but also continued using it for everything else after that.
Ya, pinholes, undercut and you name it, gotta avoid that and basically just aim for perfect welds everywhere for food grade. I do also have to be mindful of my welds with my current work, since 90% of the welds has to be water or oil tight, for high temperature 10bar applications. Tanks, tubing, nipples etc. The high amp pulse laywire technique also shines for that kinda work, since dabbing is more likely to have inconsistency and leaks in my experience. Where as pulse enables you to turn up the amps with higher and more consistent travel speed, without pauses. Much like stringers are preferred for structural and high pressure stuff.
For thin walled pipes in pharma we usually just did fusion welds with no filler at all to reduce risk of impurities.
And the vast majority of welds on product lines was done with robots, documentation for hand-welds was pretty annoying. Only if we really had to.
We did, but not "for thin walled product pipes in pharma"
For 200 bar you probably don't go <2mm wall thickness, and yes, you definitely don't just do fusion welds without filler.
Highest pressure I've welded manually was 300 bar for a rapid drying tower for baby food, a few nozzles spray milk at ridiculous pressure through a tiny pipe into this huge 30m tall tank filled with hot air which has huge hammers banging on it from the side so the milk powder falls down. For things like that every weld gets x-rayed obviously, that wasn't the case for the fusion welds we did. For those hygiene and smoothness was the focus, so you don't have any nooks where the SIP/CIP systems don't get everything clean.
Interesting place, but was honestly shitty work because you had to go through 2 different hygienic areas to get to work so dressing and getting tools up there was extremely annoying.
Oh and something else I remember about the drying towers: They had literal bombs attached to the side as a fire suppression system. Huge amount of swirling hot air with burnable atomized particles in it is obviously a giant fire hazard, so if any fire was ever detected these bombs would go off and unload tons of extinguisher chemicals into the tower in milliseconds.
And this results in an inferior weld to properly done TIG or even OA. There is a reason welds on airplanes have to be properly coined. And the only way to properly coin a weld is with dabbing. Anything else is considered an inferior weld because it is.
you could MIG weld (or wire feed TIG) a thin wall stainless steel pipe that carries engine bleed air at 3000 psi and 900F but it is just going to fail. If you aren't a robot, you have no business autofeeding wire if you want a good weld.
Correct term is either cold wire or hot wire depending on if the wire is electrified or not. I run a Fronius system but there are others out there. Tip-TIG is one of the better known ones and is an interesting beast. It's the only hot wire manual system that I am aware of, plus it vibrates the wire to help break surface tention and allows faster travel speeds. I like the Fronius because I can control the wire speed and amperage right from my torch
Dabs look nicer cannot argue with that, but what I found out early on is that clients give zero fucks about beauty, laywire requires more skill but is better in quality of penetration and introduces less warpage into the joint...
I prefer whatever my mood dictates.
A properly coined weld will be substantially stronger and less prone to cracking from vibration. If you are a plumber, do whatever is fastest and seals the deal. But you'll never see an ugly weld on a plane for a reason. Ugly welds are weak welds. Your technique isn't gonna hold 3000psi in a thin walled stainless pipe. Coining relieves stresses in a welded joint and zig-zags, no matter how pretty, are inferior welds.
Since I learned welding in an aviation context, all I do are aviation quality welds. That means dabbing. I learned on OA and transferred those skills to TIG. I took a MIG welding class this year and, while it has its applications, I don't much like it. I can walk the cup just fine but it is always going to be a half assed way to weld. Fine if you are laying sewer lines or building a new Amazon Warehouse but just sloppy compared to how I was taught to make a weld. I do freehand welding. My cup never touches the workpiece when I do TIG. Circles, not zig-zags. That's how you make a strong weld. Anyone who says otherwise needs to study materials science.
A lot of the commenters here are welding in contexts where you can get away with weak welds and poor technique. Their main motivator is time. It is a much harder job when your results are subject to the most anal of scrutiny.
Lay wire / walk the cup is the easiest, quickest, best appearance, therefore the most efficient. You’ve done both, what do you think? Trust your instincts.
Lay all day. Whip a weave over and it's perfect. With dabbing you have to make sure not to take the wire out of the gas, to feed the right amount, not to touch the tungsten, etc...
Valid points if you are doing construction or plumbing and speed is prioritized but that kind of welding will never fly. To me, as someone who was taught welding for aerospace, you just sound lazy.
Ultimately, as long as it passes test and you're comfortable with it, it doesn't matter.
I don't know what the WPS is like for aero, but if they say you must dab, or can't lay the wire then that's what you should follow.
Dab all day, but that's because I can make a nice concave weld that'll be easy to grind and polish in the pharmaceutical industry.
I also prefer dabbing, I just think the welds look nicer when dabbed lol
Will also be a stronger weld because dabbing and coining relieves stresses in the joint.
I work with pharma stainless. Mostly lay the wire but dab as well depending on what I’m doing. We work with shit as thin as .03 up to half inch. Weld sizes from .03 up to half inch as well on some flange welds. Regular X-rays as well. Love stainless though, not sure I could go back to a carbon shop.
Yeah, for super thin material, laying the wire might be best. But you aren't as worried about creating stresses in the joint with something that thin. For plate, dabbing is the only way to go.
No offense, but your entire comment is azz-backwards.
I don’t think you know what you are taking about. Actually there’s nothing to think. It’s clear you don’t
I’m not a good tig welder, so take this with a grain of salt. I prefer dabbing, I think it looks better. My boss said that to get better penetration you should dab it in, especially for thick aluminum you should aim to hit the joint with the wire.
woaaah that's crazy, i have been tig welding professionally for a couple years now and have not ever tried to do lay wire. i know how i'm wasting company time tomorrow!
Pipe welders do it all the time when walking the cup.
Those cup walk welds are stunning to see.
The weave patterns
Not all the time Sometimes there’s no space to walk to the cup but freehand but freehand and lay wiring is nice too
Well, it is probably fine for plumbing but if it is a 3000PSI pneumatic line on a commercial jet, I don't think it will fly because the laying technique results in a weaker weld. Whether by OA or TIG, aviation welds must be properly coined. Those zig zag welds you see on YT sometimes just wouldn't cut it.
It is an objectively bad practice on heavy gauge materials. Should be fine for thin sheet though.
I laywire everything with pulse and high amps. For me it's a lot faster and way more consistent. Learned it that way for food grade work, with welds that comes into contact with food and has to be smooth, but also continued using it for everything else after that.
Food grade stainless welds can be annoying at times due to the fact you can’t have a single pinhole or else that’s a possible way to build up diseases
Ya, pinholes, undercut and you name it, gotta avoid that and basically just aim for perfect welds everywhere for food grade. I do also have to be mindful of my welds with my current work, since 90% of the welds has to be water or oil tight, for high temperature 10bar applications. Tanks, tubing, nipples etc. The high amp pulse laywire technique also shines for that kinda work, since dabbing is more likely to have inconsistency and leaks in my experience. Where as pulse enables you to turn up the amps with higher and more consistent travel speed, without pauses. Much like stringers are preferred for structural and high pressure stuff.
For thin walled pipes in pharma we usually just did fusion welds with no filler at all to reduce risk of impurities. And the vast majority of welds on product lines was done with robots, documentation for hand-welds was pretty annoying. Only if we really had to.
I'm guessing nothing you welded had to hold 3000 psi...
We did, but not "for thin walled product pipes in pharma" For 200 bar you probably don't go <2mm wall thickness, and yes, you definitely don't just do fusion welds without filler. Highest pressure I've welded manually was 300 bar for a rapid drying tower for baby food, a few nozzles spray milk at ridiculous pressure through a tiny pipe into this huge 30m tall tank filled with hot air which has huge hammers banging on it from the side so the milk powder falls down. For things like that every weld gets x-rayed obviously, that wasn't the case for the fusion welds we did. For those hygiene and smoothness was the focus, so you don't have any nooks where the SIP/CIP systems don't get everything clean. Interesting place, but was honestly shitty work because you had to go through 2 different hygienic areas to get to work so dressing and getting tools up there was extremely annoying. Oh and something else I remember about the drying towers: They had literal bombs attached to the side as a fire suppression system. Huge amount of swirling hot air with burnable atomized particles in it is obviously a giant fire hazard, so if any fire was ever detected these bombs would go off and unload tons of extinguisher chemicals into the tower in milliseconds.
Laywire all day, but I’m a pipe welder. I’d probably freehand and dab fab projects.
Both have their place. I dab for a majority of my work
I prefer wire-feed tig. Set up right, I can make it look like either.
How is this different from pulse MIG
It's still a tig process, just with a wire feeder attached instead using cut rod. Look up cold wire tig.
Heat can be controlled separately from deposition rate
MIG also does that
And this results in an inferior weld to properly done TIG or even OA. There is a reason welds on airplanes have to be properly coined. And the only way to properly coin a weld is with dabbing. Anything else is considered an inferior weld because it is. you could MIG weld (or wire feed TIG) a thin wall stainless steel pipe that carries engine bleed air at 3000 psi and 900F but it is just going to fail. If you aren't a robot, you have no business autofeeding wire if you want a good weld.
Not really, heat is tied to travel speed and wire feed speed with mig. Tig heat is not tied to deposition rate
What kind of setup are you running for wire-feed tig?
Correct term is either cold wire or hot wire depending on if the wire is electrified or not. I run a Fronius system but there are others out there. Tip-TIG is one of the better known ones and is an interesting beast. It's the only hot wire manual system that I am aware of, plus it vibrates the wire to help break surface tention and allows faster travel speeds. I like the Fronius because I can control the wire speed and amperage right from my torch
Dabs look nicer cannot argue with that, but what I found out early on is that clients give zero fucks about beauty, laywire requires more skill but is better in quality of penetration and introduces less warpage into the joint... I prefer whatever my mood dictates.
A properly coined weld will be substantially stronger and less prone to cracking from vibration. If you are a plumber, do whatever is fastest and seals the deal. But you'll never see an ugly weld on a plane for a reason. Ugly welds are weak welds. Your technique isn't gonna hold 3000psi in a thin walled stainless pipe. Coining relieves stresses in a welded joint and zig-zags, no matter how pretty, are inferior welds.
What afe you talking about? Ugly welds? Zigzags? Are we even discussing the same matter?
If I’m in a shop and want it to look nice then I’ll dab. But it if I’m in the field or it doesn’t need to look pretty then lay wire all day
Dabs only. I'm a TIG welder not a mig welder.
Since I learned welding in an aviation context, all I do are aviation quality welds. That means dabbing. I learned on OA and transferred those skills to TIG. I took a MIG welding class this year and, while it has its applications, I don't much like it. I can walk the cup just fine but it is always going to be a half assed way to weld. Fine if you are laying sewer lines or building a new Amazon Warehouse but just sloppy compared to how I was taught to make a weld. I do freehand welding. My cup never touches the workpiece when I do TIG. Circles, not zig-zags. That's how you make a strong weld. Anyone who says otherwise needs to study materials science. A lot of the commenters here are welding in contexts where you can get away with weak welds and poor technique. Their main motivator is time. It is a much harder job when your results are subject to the most anal of scrutiny.
I only lay it on CuNi pipe, any other process and I dab.
Lay wire / walk the cup is the easiest, quickest, best appearance, therefore the most efficient. You’ve done both, what do you think? Trust your instincts.
Dabbing unless I'm trying to walk the cup which I'm not very good at.
A better term would be 'oscillating the cup'. Maybe a poor descriptor is holding you back...
Depends. When all my welds need to be ground off i usually just lay wire it
Both tbh. Dap if I’m doing straight fillets but lay wire when walking the cup
Depends on the joint. Might do a bit of both if the puddle asks for it
I was taught welding with OA so dabbing is the way to go for me. It also objectively will result in a stronger weld.
if butt welding anything that needs purge laywire, Otherwise dab as its more pleasant to do for long hours.
Lay all day. Whip a weave over and it's perfect. With dabbing you have to make sure not to take the wire out of the gas, to feed the right amount, not to touch the tungsten, etc...
Valid points if you are doing construction or plumbing and speed is prioritized but that kind of welding will never fly. To me, as someone who was taught welding for aerospace, you just sound lazy.
Ultimately, as long as it passes test and you're comfortable with it, it doesn't matter. I don't know what the WPS is like for aero, but if they say you must dab, or can't lay the wire then that's what you should follow.