Multipass with GMAW/MIG

Either will work. MIG mullti-pass welds are very common. You should wire wheel each pass to remove the little brown slag spots, before running the next pass. Same thing with Inner Shield.

Just an aside from a recent experience of mine. I made a davit out of 2" hitch stock. That is .250" wall. I used .030 wire (probably should have used .035" but didn't want to go buy a whole roll) The finished welds were rather large, and I ran the machine at the top of the chart. If I had it to do over again, I would either use .035 wire with mixed gas, or InnerShield. For my application, the weights and stresses are within safety limits, but I just don't like the looks of the finished product using the GMAW process with .030 wire.

HTH

Steve

Hi - multi-run solid-wire MIG -- speaking from a beginner's viewpoint I can contribute that I find it easiest to "pull" the torch for the fillet corner "root" run to optimise penetration/fusion and "push" the torch for fill passes to get good bead shape. By "pull" I mean the torch is pointing backwards to whence you have come, from ahead of the weld, so the wire is projecting backwards. That enables you to clearly see you are running at the speed at which the arc is just going down at the tip of the forming weld pool, which most burns into the plate. "push" is where the torch is pointing forward from behind the leading front of the weld, so the wire is projecting out from behind to the fornt of the weld pool.

What you would do when you are a master of MIG welding is another issue I can't comment on.

Richard Smith

From your post I assume you are a novice and do not have a lot of experience using mig. I started out not too long ago with a similar welder ( Hobart

175 ) and constructed several high stress projects with mild steel material that was 1/4" and thicker ( up to 1" ). I used flux-core wire as it gives more penetration and because many people with experience advised that a lot of mig welds produced by novices may look good but are only laying on top and have little strength. I have not had one weld fail using flux-core from my first project to my last project. I still consider myself a novice and when I want a strong weld I reach for the flux-core wire to weld it. Proper joint design is very important also. Just make sure you clean the scale off before making additional passes as suggested by Ernie.

What is the difference between innershield and outershield? Both are flux core, arent they?

Flux-core simply means a hollow tubular wire filled with flux.

Flux-core can be "self-shielded", meaning it produces it's own shielding gas, like stick welding, or it can be "gas-shielded", where a shielding gas works in addition to whatever the flux is doing.

The 2 wires are very different and are not interchangeable.

Self-Shielded Flux-core goes by many names, such as Lincoln's Inner-Shield,or ESAB's far superior Core-Shield, and it is usually run DC Electrode Negative.

Gas-Shielded Flux-core, would be Lincoln's (crappy) Outer-Shield, or ESAB's (supreme) Dual-Shield, and is always run DC Electrode Positive, just like normal MIG.

Gas-Shielded Flux-Core is restricted to indoors like standard MIG, but is incredibly hot, and clean. It is the best welding method for shop fabricated large steel structures.

Self-Shielded Flux-Core is the king of on-site construction welding. It acts just like Stick welding in that it doesn't care about wind.

The best Self-Shielded Flux-Core I have ever used is ESAB Coreshield 8.

The best Gas-Shielded Flux-Core I have ever used is ESAB Dual-Shield

7100 Ultra.

There is also another category of Flux-core that is more heavy industrial, called "Metal Core". Metal-Core wire is like Gas Shielded Flux-core only it has metal powder inside the wire along with flux for higher deposition rates.

"Far superior, crappy, supreme, the best", are these technical terms. just what criteria do you use to come to these conclusions. The real welding world certainly doesn't quite yet agree with you, but then they use chemical composition and mechanical properties as criteria.

JTMcC.

I think Ernie means that he doesn't like the Lincoln wire as much as the ESAB wire. Our shop also had to get rid of the lincoln wire cause it had some really poor welding properties such as poor bead profile and lots of splatter on any given welding machine setting with a CO2 shielding gas. ESAB was much better but cost a little more. We finaly settleld on a brand called Corex and this wire seems to have the best of both worlds (cost, weld profile, post welding cleanup and such)!

JT, it's good you are posting again. You also have not lost a step.

Esab corshield 15 runs really nice in the little units. It's a gs wire so it's single pass only. The older/ new improved Esab 717 runs really nice also. Not for the little guys though.

Damn JT, did a wild hair get up your butt again? I swear, the things that piss you off amaze me sometimes. I have been welding for 25 years. I DO have opinions of how various rods and wires perform.

Because the head of the welding program at SSCC is a cheapskate we end up using a lot of different brands of rod and wire. Whatever he can get a deal on that week is what he buys.

Hence I get to experience many different brands.

I can tell you from these years of experience that anybody who has used Coreshield 8 and then used Lincoln NR232 or 233, would never use the Lincoln wire again, if they had a choice.

Does the Lincoln wire work?....Yes. Is Coreshield 8 easier to use with fewer inclusions and better weld profiles?...Definitely.

Do you actually want to defend NR232 just because more of it is sold in the US? They sell more Geo Metros than Mercedes. Does that make a Geo Metro a better car?

In gas shielded flux-core wires the field varies wildly. Even the same wire from the same company varies. Of all the brands and wires I have used ESAB Dual-Shield 7100 Ultra is the BEST I HAVE EVER USED. Lincoln's Outershield products are a distant 4th or 5th.

Now do you give a shit what I like or don't like?...probably not. Do I really care whether you "approve" of my opinions?....not much.

"Ernie Leimkuhler" wrote

Ernie, I will correct you, but only this once. You are giving knowledge based on experience and firsthand observations. I don't believe that is an "opinion."

Steve ;-)

I'm not sure how you reach the conclusion that I'm "pissed off", but I'm not. Welding in general and consumable choice in particular are very technical fields. Opinions are fine but unless you're building very non critical stuff no ones opinion is a consideration in the choice of consumable. Out in the garage making a shelf, anything will probably do. When you venture into the code controlled world the consumables will be specified with great care, using (like I said) mechanical properties and chemical composition as the criteria, not my opinion or anyone elses.

Using your logic we can say that anyone that's run Lincoln 211 wire would never run ANY E71T-8 wire but of course since the Northridge earthquake 211 has been tossed into the dumpster for just about any serious structural work. Coreshield 8 is more user friendly and easier to run than 232. But in vast stretches of the world 232 is THE specified structural consumable. They have been trying for years to get a LA ok to run coreshield wire to no avail. Another result of the Northridge event is that consumable brand has become an essential variable on many (most) procedures.

I don't care to defend any consumable, but the facts remain. 232 is the present king in the heavy code structural world. Personally I don't like anything about running 232 wire because it has a dumb wrinkly surface, it won't ripple up right and it's just a pain to use. But it's still required on a huge amount of the outside structural work done today. Especially in seismic areas and those areas adopting the harsher seismic requirements are growing in leaps and bounds. Most following the LA template.

Any thinking individual looking at this information is going to ask the simple question "best in what way? using what criteria?" Even my 4 year old daughter won't let a comment like that go by without asking "why?".

I don't give two hoots. But we are dealing with a very technical field. Had you made plain what your criteria was in making the statements (which appears at this point to be user friendly characteristics) ) then no one would have any comment to make, people like what they like. But the guys running the mechanical tests doesn't care which wire is "easiest" for me to use. And the engineer spec'ing the welds doesn't either.

JTMcC.

Can you see these differences easily on a break test - eg. notch the weld and break in a fly press? -- between an easy-operating but lower mechanical property approvals weld and a high mechanical property approvals but more difficult-handling weld?

Richard Smith

I would doubt that. Nicks are a means to physically look at the inside of the deposit, searching predominantly for trapped slag. There are several things that are pretty hard to measure without sophisticated equipment, like elongation, low temp charpies, ect. It used to take about a million dollars of testing (normally done at the Battille Institute) before a particular consumable would be used on high pressure cross country pipelines. I know a welder that went there to participate in the qualifying of a particular style of Lincoln 7018. I believe it was when they went from LH-70 to LH-72 (both 7018 rods) or some numbers like that, anyway, they spent a million testing the "new" Lincoln

7018 before a stick could be bunred on their pipeline system. At that time they had a bunker out in a field where a machine would burn a stick of rod on the outside of a capped piece of pipe, with about a thousand pounds of air pressure in the pipe. They gradually increase the amperage till they blow thru, in catastrophic fashion. Just one of many test's that are run on consumables by the different industries using a lot of critical welds.

JTMcC.

I think they spent about a month of testing to determine that the "new and improved" Lincoln 7018 was suitable.

JTMcC.