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TIG- undercut with pulser on stainless

draganm

Aluminum
Joined
Aug 6, 2007
Location
colorado
I've been messing around with the pulser on our Miller Dynasty 350. At higher amperages and thicker material , say 1/4" stainless 316 base-metal and 150-180 amps, when using the pulser i get a raised up bead and undercut at the edges (fillet weld).
At lower power setting, like 1/4" stainless tubing .065" wall it does seem to help with pull pen. and doesn't cause problems. Is the pulser generally a low power feature? The Miller manual doesn't say anything much about it, except to "play around" with various pulse speeds and background amperages.

would like to hear some opinions from guys who are familiar with this feature.
thx
 
I primarily pulse on stainless but I do not really do certified welds except for sanitary tube. I use the pulse mainly to control warping issues. As in I have welded 2 4'x 8'sheets of 14ga stainless and had 0 warping due to pulsing. Welded the 8'seams together.

It takes years to learn pulse though. I use some 50% pt and 40% bg all the way down to 10% peak with 5% bg. It all depends on the problem at hand.

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How many pulses per second are you running?

"Traditional" pulsing seems to be around +/-1 pps...but the dynasty can go up to several 100's of pps.

You still get the lesser heat input but you're not timing your dips to the pulses.

FWIW the pulsing at the higher levels was designed to 'agitate the puddle' on thin stainless...from what I was told... I understood it to mean two pcs would flow together more quickly under the arc.
 
I have always had mixed luck with pulse, generally i have found no benefit on stuff much over 1/8". I have found it awesome on thins stuff and welded up some thin custom stove pipe parts using it to amazing effect, full penetration and effectively no burn through, internal bead or other issues.

Generally undercut means too much heat or wrong tungsten grind. with pulse on thick material and how poorly stainless conducts that heat, large high power pulses and under cut is kinda something i would expect. You could try a shallower angle on the tungsten and a large flat to keep the arc more focused at high power levels.
 
If your trying to fuse (no filler) a 1/4" fillet weld with no undercut your in for a rough time. The metal to form the fillet has to come from somewhere and if your fillet weld is "horizontal" (like a T) its going to chew out the "vertical" plate. Setting your fillet weld "flat" (so the part looks like a V) is one way to get around it. I'd likely go for more amps too, depending on what your after.
You can either set a pulse up for "slower" stack of dimes look (1-3 pulse per second >%50 background amps/pulse time) or for high speed rippled fusion welds (6-20 PPS with ~%70 background and more like +%70 pulse time on) which lets you move fast and forms the "dimes" with the pulse dropping off. 20180213_083822.jpg
Those were all fusion welded, around 120 amps, I think I was around 12 PPS with 75% on time and %80 background amps. I was tweaking pulse per second to get the ripples to look like what I wanted. They were done in a positioner with the thing set to warp speed, I think I was around 11 seconds a part weld time.
 
No reason to pulse that thick stuff... thats like gravy train welding right there. If you are trying to pulse to get your weld more consistent or better bead appearance its just a bandaid for lack of skill. Even if the machine pulse on perfect rythm you have to move the torch and keep a perfect angle and tungsten distance.
 
thanks for all the replies, as noted I will stick to it on the thinner stuff. With 9 recall memories I really only need to dial the pulser in for .065" wall stainless tubing for full-pen welds and then leave it alone. I do find straight DCEN on the thicker stuff gives much better results

just as a disclaimer, I do not count myself in the ranks of "professional welder" , I'm a machinist who has to weld SS and ALum. as part of my job requirements, There there are even some days when I almost feel like a welder;), so the helpful comments are appreciated.

How many pulses per second are you running?
"Traditional" pulsing seems to be around +/-1 pps...but the dynasty can go up to several 100's of pps.
You still get the lesser heat input but you're not timing your dips to the pulses.

FWIW the pulsing at the higher levels was designed to 'agitate the puddle' on thin stainless...from what I was told... I understood it to mean two pcs would flow together more quickly under the arc.
well the "dynasty Quick reference" laminated single-page guide that came with the machine says to try the default and go from there. The default is 100-ppm with 40% time at peak power and 25% power for the background. If I read the comments correctly this is too fast?

what pulser settings would you guys recommend for the above mentioned tubing?
 
If your trying to fuse (no filler) a 1/4" fillet weld with no undercut your in for a rough time. The metal to form the fillet has to come from somewhere and if your fillet weld is "horizontal" (like a T) its going to chew out the "vertical" plate. Setting your fillet weld "flat" (so the part looks like a V) is one way to get around it. I'd likely go for more amps too, depending on what your after.
You can either set a pulse up for "slower" stack of dimes look (1-3 pulse per second >%50 background amps/pulse time) or for high speed rippled fusion welds (6-20 PPS with ~%70 background and more like +%70 pulse time on) which lets you move fast and forms the "dimes" with the pulse dropping off. View attachment 242228
Those were all fusion welded, around 120 amps, I think I was around 12 PPS with 75% on time and %80 background amps. I was tweaking pulse per second to get the ripples to look like what I wanted. They were done in a positioner with the thing set to warp speed, I think I was around 11 seconds a part weld time.
thanks, my fillet was flat with no gap and a small V, I think the proper term is butt-weld, I was adding filler too , but it was pulling up the bead and undercutting the edges none the less, based on what you and others posted the pulser was set way too fast, or best to skip it altogether on the thick stuff.
btw, Your pic looks fantastic, I can get close to that but it's tough for me to get those results when weeks go by without any need for welding, then i have to go in the booth. It's one of the pit-falls of a job where you have to good at everything but don't have the time to be great at one thing. :(
 
Note, he said they were done in a position-er, ok that does not fully robotic-ally weld it, but if you ever do something like that with a position-er, with pulse it sure takes the skill - practice out of the equation, i had a simple disc welded to a short stub of 3" steel tube to make a shallow housing, i don't have a proper position-er - rotary table, but i do have a small pipe bender which can impersonate a rotary table, with the tig torch attached to a DTI stand and just a dab of filler at the end i could get a lovely rolled over sorta 3/16" radius of what was the fusion weld of the corner that looked gorgeous once powder coated, that case no pulse just one dead smooth weld bead. I did about 90 of them and damn near every one i was bumping the speed and current, made what would have been a hard tedious slog get done in a afternoon and gave a far better result too!

I do agree, if i have not tig'ed for a week it shows in those first few inches, its very much a muscle reflex - memory kinda thing.
 
Note, he said they were done in a position-er, ok that does not fully robotic-ally weld it, but if you ever do something like that with a position-er, with pulse it sure takes the skill - practice out of the equation...
Pulse doesnt take away so much as add new layers to existing skills. Like trying to be a meat robot and not breath while your running the weld so you dont screw up the ripples...
And it only knocks down the practice part after you have it dialed in. That pic was the best out of a batch of like 40-50 of the thingys, not all of them were that pretty but they all served their function. BUT I have to set up and dial in everything my self when I do this kinda stuff. It would be different if I was walking into a shop that had been doing the same thing (and pretty much only that thing) for the last 20 years kinda setup. Then the skill level thing shows up more...
Cheers
Clif
 
Ahhh, that is where pictures would always help with sorting out any issue. Butt welds are a different critter than fillet welds.
Undercut on a butt weld is either too hot or not adding enough filler, and depending on how your V was prepped, 150-180 might be too much amps...
Pulse gives you the ability to tweak Heat input. Heat input is the fancy welding engineering term for how hot are you making the thing your welding. With pulse you can set your Peak to a ludicrous amperage setting for the material/joint/filler combo and set everything(background % and time pulse on ect ect) just right to end up with a weld that has less heat input than running it "normal". The next biggest factor is travel speed... That is a whole different can of worms and is Completely dependent on skill and practice. Pulse can let you get away with insane travel speeds IF you can keep up with the puddle.
For the record I am just a welder (and a geek that reads too much) and get to practice basically every day... so yeah practice helps. So do pictures :D
Cheers
Clif
 
Pulse doesnt take away so much as add new layers to existing skills. Like trying to be a meat robot and not breath while your running the weld so you dont screw up the ripples...
And it only knocks down the practice part after you have it dialed in. That pic was the best out of a batch of like 40-50 of the thingys, not all of them were that pretty but they all served their function. BUT I have to set up and dial in everything my self when I do this kinda stuff. It would be different if I was walking into a shop that had been doing the same thing (and pretty much only that thing) for the last 20 years kinda setup. Then the skill level thing shows up more...
Cheers
Clif

I did not mean it as a dig, but in my experience, it really does just about half the skill level, kinda on par with the difference between manually milling a part on a Bridgeport and then CNC'ing it on a VMC, with skill they can both get the same result, but one of them only really needs the knowledge more so than the skill - practice to get a good result. getting a even bead like that around the part when you have to stop and start manually moving it around on a bench is magnitudes harder to get that kinda perfect weld!
 
I use pulsing for a variety of uses, and with 10 years of pulse practice, I still learn more every day.

I use pulse for (100% stainless)

*Warp control
*Welding bad joints, thin material
*Welding joints within 6" of wall, mainly using a mirror, this allows me "time" to run slower without burning the joint.
*Sealing welds, welds that don't need to be there, but the joint is required to be fully welded
*Looks
*Production speed on 1 off parts, kind of

But each one needs a different setup. I may use 4 different pulse setups in 20 minutes depending on what's being welded.


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