Imig200 flux core welding questions

I have a imig200 and some lincoln flux core wire. I'm looking for some pointers since the welds ive been trying dont look very good and have been coming out really black instead of having a brownish coating I can scrape off. Ive been welding 1" square tube x.065 wall.

Jody for wt&t said in one of his videos that flux core should be welded dcen. Ive tried dcep and dcen and im not seeing a big difference. Im getting alot of bbs and the weld is getting real black.

What kind of voltage and wire speed would you run for this material?

If I switch to solid wire do I have to use co2/c25 or can I use straight argon?

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Be sure the wire you're using isn't a dual shielded type that also requires gas, as Lincoln makes both types.

Yes make sure it is not a dual shield wire. Also dual shield wire with 75/25 gas mix will make a nice weld blue in color and have a slicker or smoother finish. It will also shed the flux very easily. We used Dual Shield wire in 1/16" and 5/64" diameter welding suspension parts and frames on over the road trailers for years. It is also good for welding pressure vessels tanks ect as it flows good and and has good durability.

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Originally Posted by sw2x

If I switch to solid wire do I have to use co2/c25 or can I use straight argon?

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Pure argon will not give good results- an argon / co2 mix works well. C-25 is common altho I've heard C-18 works well (but I've never used it). I've read that co2 works well on thicker material, but again I've never used it.

Is your Lincoln wire marked?

This is the wire I've been using

http://i241.photobucket.com/albums/f...ps01371ab8.jpg

It says right on the spool DCEN. With self shielded flux core wires you have to read the manufacturer's specs. Some wires run on DCEP, like NS-3M, and NR-305. Several things can be wrong here. First you really need serrated drive rolls for flux core wire. You may get away with running .030” flux core wire through a Mig gun, and maybe even up to .045”. But there are dedicated flux core gun. I've always had good luck with Lincoln's K-126 guns. The problem with flux core-ss wire is it's very stiff, and when it get hot it expands, Mig guns are very flexible, sometimes these two are just not a good match. Try to keep the gun as straight as you can at all times.
I've run tons of NR-211, then after the Northridge earthquake in California Lincoln came out with the MP. I like Lincoln's NR-212, better. But I believe Hobart's Fabshield 21-B is better than both 211, and 212.

The problem is more than likely the fact that I dont have flux core drive rolls. What exactly does the drive roll do to the wire that makes it different from a regular drive roller? The wire feeds fine... does it puncture the wire so that the flux can flow out? Sorry im a noob when it comes to using flux core wire and a noob at stick welding.

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the serated drive rolls grab the wire requiring less pressure than would be needed with the regular grooved rolls for solid wire. With Solid wire, the pressure does not deform the wire, but if you used flux core wire with these rolls, they would crush / deform the wire and cause feeding issues. The serated rollers can grap the more delicate flux cored wires requring less compression force. Test the wire feeding using the methods commonly described in the manuals, that is try feeding wire at a 45 degree angle against a non conductive surface (wood) and it should feed smoothly, into a curl. Adjust the feed rollers untill there is just enough pressure, that the wire feeds continuoulsy without stalling.

Also, first try running some beads on 1/8" clean steel, and you want to run the recommended settings in your machine table/cover. Run a drag bead, and adjust wire feed until you get a cosistent arc, no sputtering and it will be a steady sizzle sound (like bacon). No gas with this wire.

I do not have a Imig but have ran NR-211 and had no issues. I did find the hard way NR-211 does run much better pulling it than pushing. Just be sure you have plenty of ventilation if you will weld indoors.

The flux smoke/dust gets all over you and stinks when water hits it taking a shower.

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Originally Posted by zoama585

The flux smoke/dust gets all over you and stinks when water hits it taking a shower.

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Back when I was working, I would have told you it smells like money!;):D

Alway drag (pull) flux core, and push with MIG.

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Originally Posted by Big Paulie

Alway drag (pull) flux core, and push with MIG.

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What's the reason behind it ?

I only have the regular drive rollers and I've adjusted the feed rate and it feeds fine. I still get a black nasty weld... It's a good solid weld that you couldn't break, but it seems like the weld is contaminated because the weld bead is all black. If I have time tomorrow I will run a bead on some super clean metal and possibly shoot a video. I'm not the greatest MIG welder with the limited experience I have but I know that it could look alot better than it does.

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Originally Posted by sw2x

I only have the regular drive rollers and I've adjusted the feed rate and it feeds fine. I still get a black nasty weld... It's a good solid weld that you couldn't break, but it seems like the weld is contaminated because the weld bead is all black. If I have time tomorrow I will run a bead on some super clean metal and possibly shoot a video. I'm not the greatest MIG welder with the limited experience I have but I know that it could look alot better than it does.

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Are you cleaning off the flux and slag from your weld? Sometimes it can be tough to get off. Have a look at this for some good overall advice for flux core.

http://www.youtube.com/watch?v=kI7GOVrB33c

Good rule of thumb, anything that produces slag you should drag / pull.
Here is some .045” NR-212 run with a 47-year old engine drive.

My experience with Flux Core is your metals being welded have to be really clean. Grind or sand the areas being welded. Mil scale, rust, dirt or other contamination that you can occasionally get away with using gas mig or stick will wreak havoc with flux core. I'm on my 3rd 10# roll of Lincoln NR211 and still occasionally have bad runs with porosity, nasty looking beads, or the black color that you are referring to. As a rule the flux on a good weld will be a white/tan color and 90% of it comes off with a wire brush.

As an update - I just finished a large project using my Northern Tool MIG/Stick 200 (being used as a simple wire feeder for my older Miller Bobcat 250 - no duty cycle to deal with). About 50% of the welds were on fresh cut box and strap (3/16 wall box, and 1/4 to 1/2 strap). I did not have the time to grind and sand all the joints clean and some of the plate was covered in rust. I was surprised to see how little trouble I had with porosity. Maybe 1 in 10 welds had visible pits. Not all that concerned with it, these are non load bearing welds, just have to hold the parts together.

Went through 3/4 of a new 10# spool of Lincoln NR211 .035. No problems with weld color, or flux removal. Welds came out a dull silver color with nice ridges (there's a first for me), and the flux was off white to grey depending on what I was welding - clean/dirty. Wire brush got 95% and the thicker portions just needed a little scrape to flake off. Even the spatter (typical with flux core) was minimal and scraped off just as easy as the flux. Only went through 1 tip on the MIG torch.

NOTE - the drive rollers on my NT MIG are not serrated. Top roller is smooth, bottom roller has a grove for .030 to .035 wire. No feeding problems. Maybe I am lucky, or I just followed the directions and set the tension properly.