Pulsed MIG Welding

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I completely understand pulsing for TIG welding, but why would this be needed for MIG welding?
Reply:I have pulse capability on 2 of my migs. On my old one, I have slow pulse, basically on/off timers for the arc and feed. It was developed to do automated stitch welds, and look kind of like tig welds. I gave up on that. It came in the package with the spot timer which I did use for a while. It is a millermatic 200 with spot/pulse timer and spoolgun. 1986 vintage.The other is a fully automated digital mig. High pulse, low pulse in the arc mode only. During short arc welding, it controls the drip rate and modifies the profile and appearance of the weld. It can also reduce spatter if programmed correctly. Spray arc really does not take advantage of the pulse features so I just don't use it for that. This one is a millermatic 350P with alumamig push/pull gun and dedicated to aluminum. 2009 vintage.Some others may be able to explain better than I have, as I really don't take advantage of pulse on my migs.
Reply:Originally Posted by morgaj1I completely understand pulsing for TIG welding, but why would this be needed for MIG welding?
Reply:Originally Posted by morgaj1...why would this be needed for MIG welding?
Reply:I can only speak for the Miller 350P.On thinner material, the pulse limits heat input.  It allows slower wire feed rates as well.On thicker material, it can be tuned to give deposition rates in line with spray transfer, but that 'off' part of the pulse allows the puddle to cool just enough so you can work out of position (doesn't have to be flat).Personally, on steel, I like the look and control of short arc better.  I like watching the wire hit the puddle.  If I was to do a long bead, nice an straight I would consider pulse.  A little less distortion a little more speed.  I have used pulse on exhaust pipes (mild steel, relatively thin crap) but 90% of the time I use short-arc.Aluminum I do 100% pulse with MIGCon Fuse!Miller Dynasty 350Millermatic 350P-Spoolmatic 30AMiller Multimatic 200Hypertherm PowerMax 1000G3Miller Maxstar 200DX
Reply:Originally Posted by Black WolfOne answer is for Gauge Metal to help help control total heat input - aids in minimizing burn-through, and warpage.I'm with Broc on this one, but I'll take it a different way - If you have to ask this question, you either don't understand what the Pulse Option does, or you are perhaps one of those fellows who uses it incorrectly and think it is merely for appearance.
Reply:Fair enough then.  If you understand what the pulse process does for GTAW (TIG) then you will understand what the pulse process does for GMAW (MIG)The principles are the same, as are the results.  Most GTAW (TIG) machines allow you to set Welding and Background Amperages/Voltages as well as Ramp times to customize to your specific needs and application.Pulse GMAW (MIG) is more "Automatic" where you set the Wire Feed Speed, and the software selects the Voltage for you - The user then adjusts the "Trim" to alter the frequency of the cycle to adjust the heat input.Pulse GTAW (TIG) can be very slow - Like tapping your foot. Lots of learners use it to get their timing down while using the "Dip" Method.<-- This is where learners use it as a "Crutch" and is where my comment about appearance came from.  This is NOT what Pulsing was developed for - It is about the material, not the user.Pulse GMAW (MIG) sounds like a LOUD buzzing bee. Pull the trigger and GO.Hope that helps.Later,Jason
Reply:Good explanation.  Thank you.
Reply:Originally Posted by Black WolfFair enough then.  If you understand what the pulse process does for GTAW (TIG) then you will understand what the pulse process does for GMAW (MIG)
Reply:I have used Miller, Lincoln, and Fronius pulse machines and they all are really good in my opinion.  These are some good points of pulse usage and explanations.I personally would rather use pulse then any other process for GMAW.  For me the best way to explain this is because you get the heat parameters of Short Circuit but the advantages of spray. So you get a low heat input and can weld all positions and get the great penetration and low weld spatter.I have qualified a couple WPS with the Lincoln 350P on pipe and military armored steel. I love it.  Not so good for welding on dirty materials but you should be welding clean stuff for a good weld anyways.
Reply:Originally Posted by con_fuse9Well, with TIG you have two options for pulse, a slower pulse one you can even time your dip to, or a high frequency pulse that can help focus an arc (and thus focus the heat).  With MIG, the pulse seems to allow a controlled spray transfer process - with adjustable arc length and focus (at least those are the adjustments on the Miller).That is true for most of the modern pulsed MIGs.  They advertised Synergistic settings.  You basically set the wire speed and the machine does the rest.  However, the draw back is you only can do this for pre-programmed wires/processes.   Want to try pulse with a wire that is not pre-programmed, you are on your own.  That's where it gets rough.  Now you have a zillion options.  I'll let others answer but I think with Miller's pendants you can use pre-programmed or go manual mode.What I really like about the Miller setup is once I got used to it all I do is pick a wire speed - the machine does the rest.  I think I could use a little more 'hot start' - starting the aluminum with extra power to burn it in.  If I set the wire speed a bit too low, it will run, just setup high (like not enough voltage).  Too high, and I can melt through.Hope that helps.
Reply:there are several points not made yet that may be worth mentioning while trying to compare pulsed MIG and TIG.I'll confine my remarks to the MIG side and limit the scope of my reply since the subject is so wide the main manufacturer's have whole departments of welding and electrical engineers that deal with little except this topic.MIG can be done in spray mode or short arc mode and short arc mode can be very clean and a much better weld in aluminum for example if the shorting arc were steady.Pulsed MIG power supplies are able to monitor the arc circuit and surge and chop the weld power to create a very high speed series of (relatively huge) droplets that are called globular transfer welding. This is actually a subset of shorting arc but in this mode the entire end of the wire forms on huge droplet and that is deposited into the weld almost like TIG filler; molten but not in tiny droplets.This method of welding can avoid the gas bubbles native to aluminum MIG getting trapped at the root face of the weld by allowing a very highly molten puddle with much less surface area of the filler metal's transfer to fill the entire puddle without having to coalesce droplets thereby trapping gases or contaminates.By having 'gazillions' of tiny droplets of metal as common in spray mode the weld may show porosity as gas is left in the root by the high freeze rate of the parent metal.  So if tiny droplets are formed to transfer the wire to the puddle the relative surface area of the droplets is much much higher than if only one big droplet of molten metal is formed.By using a MIG power supply that can create huge droplets very fast (pulsed MIG or pulse-with-pulse) the weld can be cleaner, have better fusion at the root face and also have a nice clean top finish face.This fact of pulsed welding allows a power supply that has a circuit monitor which automatically adjusts to this wire feed arc burn and wire deposition method to deposit a much less porous weld compared to spray mode.So, I'd say the pulsed MIG (my only experience is the Lincoln 350MP Power MIG ) creates an increased bend break weld, cleaner root face, and overall better quality when welding MIG in aluminum.I don't do enough steel to remark so I'm focusing here on the aluminum aspects of the original question.Cheers,Kevin Morin
Reply:High speed pulse on alum mig or tig is generally lost on me. I have used it on alum when I want to soften the arc, if I am too lazy to reconfigure or don't have separate programes like my Dynasties.Steel is another matter, highly useful.