Flux not covering consistently (Flux Core)

[JohnP]

Hello,

This is my first post to the forum. I've enjoyed reading the different posts and advice. I've been welding for about a year and just finished the stick welding part of a beginning welding class at my local college.

I just acquired a used MillerMatic 35 that I have setup for .035 flux core (Lincoln NR211 Innershield). It seems to weld smoothly, but I cannot obtain an even flux covering on the welded bead. The small amount of flux covering is a narrow band mostly in the center-top of the bead. The sides/toes of the bead are bare of flux and have a dull, grainy appearance. I've played with different voltage/wire speeds, but can't seem to find the right combination. Any help is greatly appreciated. TIA.

John

[welder28]

Flux core wire in that size welds VERY slowly. You can stick weld w/ 3/32" 6010 faster than .035 self-shielded flux core on a little 120V machine. Just pause for a long time and weave slowly and kinda narrow. The biggest bead you can make on a fillet weld is about 1/8" (that's 1/8" up from the root on the vertical plate and 1/8" out from the root on the horizontal plate).

[jsoukup]

I use the NR-211 in my Lincoln 135, I have slag, but not a tremendous amount. Usually just a couple of love taps with the slag hammer and it's gone. What I see more of is "gas residue?" (tell me if you know a better name) You know the little grey powder that forms around your weld from the self-shieding gasless wire. I get a lot of it, and frankly it's a pain to wipe up before painting. You see the same thing if you're stick welding.

[dda52]

Flux core wire in that size welds VERY slowly. You can stick weld w/ 3/32" 6010 faster than .035 self-shielded flux core on a little 120V machine. Just pause for a long time and weave slowly and kinda narrow. The biggest bead you can make on a fillet weld is about 1/8" (that's 1/8" up from the root on the vertical plate and 1/8" out from the root on the horizontal plate).

welder28
Not sure where you get your info, but it isn't correct. The Millermatic 35 is a 230v 150amp (rated) machine. It was produced as late as the very early '90's. It was designed primarily as a sheet metal MIG, but will chew up 1/4 quite efficiently. ( been there, done that ) With flux core, and a skilled operator, it could be pushed up as high as 5/16 single pass and 3/8 multi pass. At 450ipm, it has deposition rates of 7 lbs per hour according to the Miller calculator. I'm not sure how that translates to slow. That is actually very good for a MIG that size and larger. Duty cycle will probably bring that rate down to around 5 lbs, but that is still good.

As to flux core .035 making only 1/8 x 1/8 welds, not sure where you got that one either. The HH and MM 135's are rated at 3/16 with .035 flux core. That means they WILL be able to make a sound weld at least 3/16 x 3/16. Again, with a skilled operator, that can be pushed up a bit. Speed with those little machines is up to the operator. I run them side by side with a stick machine. Most of the time, the duty cycles being equal, the MIG will be the fast one. Of course, joint composition, work location, experience level of the weldor and a host of other factors will affect the deposition rates. This has just been my experience. Stick is at a disadvantage with a deposition efficiency of only 60%. I believe flux core is slightly higher and MIG is at 75-80%.

[dda52]

John P
I may be wrong, but I believe that the actual shielding with FCAW is from the decomposition of the flux and the slag is just the byproduct of that decomp, the same way as it does with a stick. The decomp of the flux actually produces the gas that shields the welds, not the slag itself. So if that is correct, and some one correct me if I am wrong, then if the slag doesn't cover the weld, it doesn't necessarily mean the shielding to the weld is incomplete. I don't ever remember the slag completely covering the weld the same as with a stick. There is a big difference as to amount of flux and type in FCAW vs. SMAW. If you have doubts, just make some test pieces and womp them ( or bend) with a big hammer. That should tell you if your welds are good.

[welder28]

Well, ok then...I was thinking of a little wimpy hobart 135 style welder which only has the power to make about a 1/8" bead. Yay for you...ya caught me.

[david_r]

Don,
Is that deposition rate correct? Not disagreeing just amazed that it'll lay down over 5 times what stick wll do.

welder28 that was real gracious of you

[Zrexxer]

Figuring a 0.035 solid wire, I calculated the cross sectional area, multiplied by 450 ipm for 60 minutes, then converted to cubic feet. Based on the unit weight of steel, that comes out to about 7.3 lbs/hr. Of course, flux cored is going to be slightly less due to the hollow core. So yeah, it looks like Don's numbers are pretty close.

[Guest]

Well, ok then...I was thinking of a little wimpy hobart 135 style welder which only has the power to make about a 1/8" bead. Yay for you...ya caught me.

Sorry, W28, I gotta disagree with you on this one, too....I did this with a Hobart 90 amp Handler...the first model out....this is 1 1/2" rebar....welded with .035" E71T-11 fluxcore.

The HH135 will weld 1/2" with a skilled hand.

[Guest]

Hello,

This is my first post to the forum. I've enjoyed reading the different posts and advice. I've been welding for about a year and just finished the stick welding part of a beginning welding class at my local college.

I just acquired a used MillerMatic 35 that I have setup for .035 flux core (Lincoln NR211 Innershield). It seems to weld smoothly, but I cannot obtain an even flux covering on the welded bead. The small amount of flux covering is a narrow band mostly in the center-top of the bead. The sides/toes of the bead are bare of flux and have a dull, grainy appearance. I've played with different voltage/wire speeds, but can't seem to find the right combination. Any help is greatly appreciated. TIA.

John

It sounds like you were pushing the weld...I do this and get the same result. I don't think it's all that bad, but you will get better flux coverage by pulling the weld. Keep in mind it won't cover like stick electrodes do...there's just not the same amount of flux to contend with. But it's still OK.
Welcome to the forum. John...good to have you aboard.

[dda52]

I was hoping you would chime in, Rocky. I liked the pic you had of a machine part or something that you did with a 135. All I remember about it was I wouldn't have thought it possible. All your pics should have a disclaimer.."Don't even try this, you can't do it!! " or maybe something along the lines of "When you can take the stinger from my hand..." Sorry, couldn't resist. Since you said this a long time ago, I've been using the MM 135 on bigger stuff and getting surprisingly good results. Now that the Bobus is up and running, it may get all the big stuff, just for the exercise.

David R
I got that figure from the MIller calculator, flux core side but a solid wire figure. I messed up the duty cycle figure a bit. Figuring duty cycle at 60%, it looks like it would be closer to 4.3 -4.4 lbs/hr....I think. I'm still getting some of this figgerin stuff down. When I looked it up, I couldn't find any stick figures anywhere....still can't. That book is always running off. I guess the difference is the lack of waste compared to stick and the fact that all you do is pull the trigger and let her rip. It adds up quickly it seems. The deposition rate was higher than I expected too.

[leanangle]

Hey all, brand-new welder here. Not really qualified to be handing out advice, but since I had this same problem recently and think I have it figured out, I thought I'd chime in. I've only been able to find this question asked two places in all of the internet, with no definitive answer, so hopefully this helps someone in the future. I'd also appreciate input anyone might have regarding the root (pun totally intended) cause of the observed behavior.

In my case, my first-ever stringer beads had plenty of problems, but slag coverage wasn't one of them. That changed, however, in the next couple days of practice. As everything else about my beads got better, the slag coverage issues got worse. I experimented with every parameter I could, to no avail. Then I realized that the one thing different between my first-ever beads and my nose-to-the-grindstone practice is that I set up a fan blowing across the work to keep me from breathing in the fumes! So I turned off the fan, and whatdayaknow... no more slag coverage problems. Now, without a fan, I notice that the only times there's a break in my slag is in spots where the wind temporarily kicks up, and can predict where the breaks will occur based on that.

I guess (this is the part where I'd love to hear what y'all think), the cause is either (or both): The wind physically blowing off the compounds that would otherwise cool & solidify over the surface of the weld, or the weld cooling too quick to allow the same compounds to bubble up to the surface. Does either make sense?