MM252 and Spray on heavy plate

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I have some work coming up thats 1/2"-1" plate. I've welded this heavy of plate before with stick, but would like to use spray transfer now. I understand this will be a the top-end of the MM252 and particularly the M25 gun. I plan to pre-heat and allow the gun/machine cool time in between welds.My question is the shielding gas. I plan on running .035 wire. From what I've read a 98/2 mix will allow the machine to get into a spray with lower settings, but penetrates less. I will be the best penetration I can get, so should I got with a 85/15 or 90/10 mix?Please only those with first hand experience with spray reply, thanks.
Reply:THe M-25 gun will not hold up. I have had good luck with 90-10 otherwise the Stargon blends work well. If it was me I would use .045 dualshield like 71 elite or 7100 ultra with co2 gas.Miller xmt304,  Miller S22 p12, Miier Maxstar SD, Miller 252 w 30A, Miller super32p12, Lincoln Ranger 9, Thermal Arc 181I with spoolgun, Hypertherm 10000 ,Smith torches. Esab 161lts miniarc.
Reply:I've used 98/2 and 90/10 with a MM250.  Didn't like the 98/2.  The puddle was too fluid.  With good joint prep you won't need preheat, but the duty cycle will be short . . . especially for the gun.  You'll be replacing it soon.  And get some good gloves.  Compared to short circuit, the arc is really hot.Dynasty 300DXSmith He/Ar gas mixerMM350PHobart Handler 120Smith LW7, MW5, AW1A
Reply:85/15 will give you the maximum penetration with spray transfer, all other things being equal.  However, I'm going to also suggest going with a gas shielded flux cored wire.  If you're considering spray transfer with hard wire, then you're working in the flat position.  There are some excellent E70 class T-1 flux cored wires that will give you great deposition and excellent penetration. Hobart Fabco TR-70 and Select Arc 70TR are two products that I found that come in 0.045" diameter.  LIncoln and ESAB have E70T-1C products as well, but the smallest diameter I found was 1/16".  This size wire would demand more amperage than your 252 can reliably deliver.  You can go with an all position E71 class wire, but you won't get the optimized performance of a wire designed to run in the flat or horizontal positions. There are more all position wires available in 0.045" diameter.  Depending on how big the job is, an all position wire might be more useful down the road if you have wire left over at the end of this project.It'll be easier on your MM252 to run the flux cored wire.  100% CO2 gas is cheaper and will do a better job of keeping the gun's contact tip and nozzle cooler.  Most folks don't realize that the duty cycle for MIG guns is usually determined using 100% CO2 gas, and can be much lower using Ar/CO2 or other blends.Benson's Mobile Welding - Dayton, OH metro area - AWS Certified Welding Inspector
Reply:For spray I'd go either 98/2oxy or  90/10CO². As the CO² content increases, in the shielding gas, it requires more voltage and amperage to transition over to spray transfer. Going with 85/15 you'd give up some spray transfer range that the other 2 gas mixes would offer. I'll point out too, that when I tried 85/15 on the old MM 250 at work, I couldn't get it to transition over to spray. I never did try  85/15 on my  MM 251 that I use to own here at home. I used 98/2 and 90/10 with my 251 and it performed well with both.  90/10 does produce a little deeper side wall penetration then 98/2. Both gas mixes are quite capable of producing sound welds though. As pointed out 98/2 does produce a slightly more fluid weld puddle. The 98/2 puddle is very controllable, by dialing in a tight arc length, and using correct gun angles.ESAB Migmaster 250 Hobart Ironman 230Multimatic 215TWECO Fabricator 181i & 211iHH125EZ - nice little fluxcore only unitMaxstar 150 STH - very nice
Reply:@ Dan - 98/2 Oxy's my GoTo for axial spray'n with the XMT304.  High fluidity, but super control and depth of fusion for 1/4in + mild steel plate.  Did, however, learn that during burn-in you don't seek the ultra-quiet (almost silent) emitted sound.  Rather, control the gun's attitude and maintain the proper the CTWD in order to produce a slight hiss w/ occasional pops.  An exercise in balance.  This approach seemed to improve the bead's overall appearance and net wetting.  Looking forward to soon coupling the Miller Optima into the process for pulse spray'n in 3G."Discovery is to see what everybody else has seen, and to think what nobody else has thought" - Albert Szent-Gyorgyi
Reply:Originally Posted by ManoKai@ Dan - 98/2 Oxy's my GoTo for axial spray'n with the XMT304.  High fluidity, but super control and depth of fusion for 1/4in + mild steel plate.  Did, however, learn that during burn-in you don't seek the ultra-quiet (almost silent) emitted sound.  Rather, control the gun's attitude and maintain the proper the CTWD in order to produce a slight hiss w/ occasional pops.  An exercise in balance.  This approach seemed to improve the bead's overall appearance and net wetting.  Looking forward to soon coupling the Miller Optima into the process for pulse spray'n in 3G.
Reply:Originally Posted by Duratrac85I have some work coming up thats 1/2"-1" plate. I've welded this heavy of plate before with stick, but would like to use spray transfer now.