Why use SMAW for deeper penetration?

[D.sebens]

Seems like people recommend arc for deeper penetration on large joints. Why is this? If you had a 200amp arc welder and a 200amp mig, whats the difference?
I’ve also heard flux core mig offers deeper penetration than plain wire with shielding gas. Why is this?

 

[pontiac428]

Flux core MIG at around 150A is capable of spray transfer mode welding using 1-2% oxygen in Ar-CO2 (Praxair Stargold). The oxygenated gas allows the penetration profile to root much deeper than globular transfer modes typical of MIG welding. Spray mode makes a deep, strong, attractive weld that is hard to control in the vertical or overhead. I think of it as a good structural setup, and use it when I can. It's a neat way to do it. There is no knob to turn or button to push, it's all in the heat and feed once the gas is right.

 

[rabler]

Seems like people recommend arc for deeper penetration on large joints. Why is this? If you had a 200amp arc welder and a 200amp mig, whats the difference?
I’ve also heard flux core mig offers deeper penetration than plain wire with shielding gas. Why is this?

I've asked myself that same question. Not an expert welder by any means, but I think there is some factor that MIG is just an easier weld technology favoring beginners, and can make a decent looking bead even if not really melting in, so is a more error prone technique. Also occurs to me that a welding rod for stick is typically around 1/8", give or take. A MIG wire is often around .035. That's about 1/4 of the thickness. Seems to me that the MIG wire gets melted away faster and further from the puddle, whereas a stick can be pushed in closer because of the diameter. Pushing the feed rate up does help with MIG penetration.

Of course, maybe it's as simple as the stick slag helps hold in heat?

 

[dirty tools]

They are lots of factors to look at
type of material
thickness of the material
length of weld
welding position
strength of weld required
what the product is to be used for

 

[D.sebens]

That’s what I’m asking lol. Seems like amp for amp arc penetrates deeper. Or it’s at least preferred for thick metal.

 

[Cadillac]

I think it has to do with how the current is going through electrode/rod vs. mig gun/wire. Really don’t know.
I have seen demos on the difference of tungsten angle point to penetration with tig And it make a difference.

 

[General Zod]

Flux core MIG at around 150A is capable of spray transfer mode welding using 1-2% oxygen in Ar-CO2 (Praxair Stargold). The oxygenated gas allows the penetration profile to root much deeper than globular transfer modes typical of MIG welding. Spray mode makes a deep, strong, attractive weld that is hard to control in the vertical or overhead. I think of it as a good structural setup, and use it when I can. It's a neat way to do it. There is no knob to turn or button to push, it's all in the heat and feed once the gas is right.

I don't think he is talking about gas-shielded flux-core (FCAW-G). I'm pretty sure he is talking about your standard E71T-GS or E71T-11 gas-less flux core wire.

That’s what I’m asking lol. Seems like amp for amp arc penetrates deeper. Or it’s at least preferred for thick metal.

MIG and TIG are also "arc" welding process. They too use an electric arc. SMAW or "stick" welding may obtain more penetration than solid-wire MIG using C25. I say "may" because it is not always the case. There are enough differences in SMAW electrodes that one cannot properly make a solid across-the-board generalization to the arc characteristics.

Two examples:

• Solid wire 0.030/0.035" ER70S-# with C25 gas vs E6013 3/32" SMAW
  • Both at, say 100A, penetration will be very similar. E6013 is a low-penetration SMAW rod, so it kinda evens out.
• Solid wire 0.030/0.035" ER70S-# with C25 gas vsE6010 ⅛" SMAW
  • Both at, say 100A, and the 6010 will obliterate ¼" steel, while the ER70S-# will barely be cutting into ⅛" steel. 6010/6011s use a cellulose based flux which produces hydrogen gas with the shielding plume. This raises the arc voltage due to the exothermic nature of hydrogen gas near an electric arc, which is responsible for the deep, driving, aggressive arc that, if one is not careful, will gouge out the base metal.

 

[SLK001]

The stick welding rod has a covering that holds up just long enough to allow the arc to create a plasma jet directed into the weld. This jet is what allows the stick to penetrate much deeper than a MIG or TIG welder.

 

[Karl_T]

Stick welding in general has better penetration. It just welds hotter with the larger diameter rod and flux covering to hold the heat in.

Now you can really play games with the amount of heat penetration.

First, reverse polarity causes more heat in the part and deeper weld. Straight burns the rod faster and less penetration.

larger diameter rods weld hotter and deeper. Rod diameters go from 1/16 to 1/4 by 32nds

then there are rod type differences. 6011 is designed to burn really hot and deep. Don't even think about reversing the polarity on this one.

I run 6013 straight on thin steel and reverse on 1/4" plus steel.

7014 straight can run at very low amps without sticking the rod. Use it to fill in holes the steel - takes practice to do this.


MIG is just plain too easy to a make a purdy weld that does not have complete penetration. I suggest most should use stick if going for serious strength on material 1/4' thick or more. Can MIG be used here?? Sure.

Karl


PS print and keep this power chart on your stick welder. I use it every time i stick weld

 

[Aaron_W]

Not a pro, not even a very good welder, but I suspect on a theoretical level the same can be done with either Mig or stick, but it is just easier to get better penetration with stick or flux core because the flux coating the stick / filling the core provides the "magic" while Mig may require the use of an exotic shielding gas to get the same performance.

Most people just use CO2 or an Argon / CO2 blend, but for specific uses Mig can use far more interesting gas mixes. It is a lot easier and often cheaper to just buy a pack of specialty welding rods / small spool of flux core, than it is to buy a tank of highly specialized gas for each type of welding.