slag on 1" plate and dual shield flux core

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Im welding 1" A36 plate with the hard mill slag over the entire surface im sure you guys are used to seeing, using lincon electric 71A75 ultracore .045 with 75/25 gas running about 560in./min (i think 600 is max). I work in a small agricultural shop and this particular process is used in the manufacturing of 5000lb off-road forklift frames. I have been welding with this smokey **** on and off for the last 2 years with probably 200hrs of actual welding time. The welds have improved tremendously from the first few welds but i just cant seem to get the toe of the welds to remain consistent. Im thinking its due to amount of mill slag im trying to weld through, at times i can see it popping off in front of my puddle and removing the slag before welding is just impractical. Anybody have any pointers?  production on another 6 frames is due to start in about 2 weeks. (cough..gag..) i cant wait...
Reply:Our guys at work weld through mill scale all day every day.  We use Excel Arc 71 .035 wire and straight CO2.
Reply:I use that same wire at work.   Anything over 1" I grind the mill scale off the weld area.  The puddle flows much nicer, and the finished weld has a much smoother appearance.  That is the one thing I don't like about this wire, it doesn't tolerate millscale on thicker sections very well.   Personally, I find the results worth the little bit of extra effort to run a grinder down the joint prior to making a weld.  560ipm is cookin.  I typically weld at 27v 425-450ipm.  Most of what I weld is A36 or grade 50 plate.Another option may be to investigate different wires.  Years ago we used TriMark Tripple-7, and millscale didn't affect it much.  The reason we switched was that that wire was prone to worm tracks in the weld.  Even stepping up to a larger diameter wire may help out with the millscale issue.Last edited by Static-XJ; 12-31-2010 at 08:05 PM.
Reply:Hey wow thanks, i really appreciate the suggestions! Its been such a headache with this stuff, im not in charge of purchasing but im sure gonna make a few suggestions monday. This is my first time on this forum by the way, im just a young duffer at 23 but ive been welding/fabricating fulltime for almost five years and my old man was a welder forever. Hopefully i can answer a few questions in the future here.... Thanks again for you time guys
Reply:Do you have a needle scaler? I found that it was fairly easy to break up the mill scale after a preheat with a weed burner with a needle scaler back when I welded mining equipment. Even if I didnt completely remove it, having it broken up helped a lot with getting the toes to wet in.
Reply:second for triple 7. It is what I use almost all the time at home and work. On anything from 1/8" to 1 1/2"thermal arc mst400, va4000 feeder, lincoln 175 min, victor torches, miller s32p feeder, air arc k4000 for work.
Reply:I run either Triple 7 or Hobart Excel Arc 71 both with 100% CO2 and mill scale(unless it is really bad) is the least of their worries, both are much more forgiving than the Lincoln or the ESAB dual shield wires. A needle gun or a stiff wire wheel usually will make short work of most mill scale.Disclaimer; "I am just an a$$hole welder, don't take it personally ."
Reply:grind it off !!!!!!!!!!!!!!!!!
Reply:I agree with GMC and Tozzi with the 100% Co2. Anyone using C25 with flux cored wire and A36 is just tossing money down the crapper. The Co2 sheilding provides better cleaning and a better penetration profile for less dough.Cored wire up to 1/16" works well in all positions and can be turned up enough to handle 1" in the flat/horizontal very well.I'd add that with less than 200hrs use over 2 years I hope they don't leave partial spools laying around outside of a rod oven, this stuff is a "use it or lose it" deal without an oven.Matt
Reply:the lincon rep that sold us on this wire was just raveing about how well it handled millscale too... Im going to be slowin it down to around the 450 range, 520 is a little out of control
Reply:I was thinking the same, that wire speed is quite high. Also have to agree with everyone, 100% CO2 is the way to go with out a doubt. I normally weld from 3/4" to 6" thick plate. We run 100% CO2 and depending on what needs to be welded, we grind but not often. A 3 1/2 inch thick lifting lug that holds our 42,000 lbs frame would be ground. (also preheated being over 1" thick)I wear a respirator and a fire dept. issue balaclava for the intense light. We run .052 and 1/16 flux core wire.    .052 is normal at 28 volts, 330 on the wire average. (Lincoln wire)or the North backpack which goes over your back, works great for lots of smoke or when welding over nasty materials like aluminum. Last edited by oxygen454; 01-02-2011 at 01:43 AM.