good-range - MIG/GMAW welding CV vs. Pulse

Mar 14, 2025 Last reply: 1 year ago 5 Replies

Hello everyone.



Welding newsgroup seems defunct. This may or may not be excessively abstruse .



Continuing welding, working in a FabCo. More than 4 months back at it now.



"My" welding machine, a Miller MigMatic 320i, is a Constant Voltage GMAW / MIG welding machine. It seems to be internally an inverter, but is Constant Voltage output. It is an "economy" industrial machine.



Everyone else has "pulse" machines, which are minimum 5X the cost.



"My" situation is made more difficult because almost all our thicknesses are in the 5mm to 8mm range - right where for Constant Voltage you will be in the "globular" transition domain between dip-transfer (lower thicknesses) to spray-transfer (higher thicknesses) fundamental physical domains. So I am forcing "I intend spray and finagle it to be so" or "I intend dip and make it so". Crazy big adjustments of both wire-feed-speed and Voltage between different welds on the same job.



For the "pulse" machines this is a non-point - they are in pulse all the way from low powers up to high powers, with no transition range. Nice "just right" fluid weld pool etc. through the range.



I suspect the pulse machines with their "proprietary special high-productivity" pulse modes sense how long the arc is and where the weldpool surface is - that they are "fly-by-wire".



I met / found this almost 15 years ago

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"Waveform analysis for MIG / GMAW "Lincoln RapidArc" on steel" As some pillock who had stumbled on this while doing a bit of research, Lincoln told me what this does for their industrial customers - and going back with an armful of offcuts I found that is exactly so - it will "run" absurdly fast while keeping control of the weld-pool and giving the sought weld bead shape. But yes part of that pulse cycle I logged and graphed is "feeling" where the weld pool (surface) is. "fly-by-wire" ...


Anyway - to the question...



The "pulse" machines seem to have such a broad "good zone" you simply set the thickness, irrespective of joint geometry, etc., etc., etc - and it welds perfectly.



With "my" CV machine, I have a great big archive of welding conditions for each {thickness; joint geometry; high-penetration or high-deposition; etc., etc.} Then unique jobs with special conditions.



10's into maybe hundreds of them.

So the CV machine has a very very narrow "good-zone" / "sweet-spot"; while the "pulse" machine with seemingly its "fly-by-wire" has such a wide "good-zone" that you have this "one-size-fits-all" dial-in the thickness.



Anyone else know of this?



Rich Smith


The Miller Welds Forum still had some activity last time I visited.

That being said, welding is part of metalworking so your posts should always be welcome here. I sometimes learn something from your posts, and sometimes am forced to go look something up so I can pretend to understand it. I certainly have no issue with you posting here.

Let's see if any comments come along. I am grateful for all help received, and am philosophical that maybe this post will be read and if taken as plausible will shed some implicit impression of what welding is like - no more than that. Regards,

I read most of your posts , even the stuff I don't understand - yet . Your technical knowledge is way beyond what I "need" to know , but it gives me insights into why sometimes things I do get unexpected results . Keep on posting !

I read most of your posts , even the stuff I don't understand - yet . Your technical knowledge is way beyond what I "need" to know , but it gives me insights into why sometimes things I do get unexpected results . Keep on posting ! Snag

---------------------------------------- I appreciate them even though my MIG is limited to auto body repair. My broad knowledge outside the immediate subject helped me find a work-around to solve problems the deeply but narrowly educated engineers hadn't. If I couldn't fix it I knew what type of expertise to call or measuring instrument to buy or build.

For example a very precise custom instrument I built had a mysterious ~30KHz noise interference. The engineer suggested filtering but I solved it by creasing and stiffening the side panels to eliminate capacitively coupled resonance from the building's ultrasonic intrusion detectors. I traced an unsolved random DC offset error in an op amp circuit to rectified pickup from a local AM radio station.

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