Penetration: Solid vs Flux-core wire

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Can anyone explain why better penetration is achieved using self-shieded flux-core wire?  I've experienced the better penetration abilities of flux-core, but would like to understand the physical characteristics and chemistry involved.  Any welding professors out there?--Mike
Reply:Current density. JTMcC.
Reply:Why would current be more dense with flux-core?--Mike
Reply:Tubular wires (flux core and dual shield) have a much smaller cross section than a solid wire, a straw shape as opposed to a solid bar shape.That smaller cross sectional current path makes the "arc stream assume a more columner pattern" resulting in deeper penetration.That straight from Esab literature. Current density is the ratio of current to the cross sectional area of the electrode. Current density has a big effeft on deposition rate and some effect on penetration. JTMcC.
Reply:Excellent. That's the info i was looking for.  Good explanation.  One more area of my welding knowledge base firmed up --- and one area of ignorance knocked down!  Thanks guys.--Mike
Reply:TO my understanding, FluxCore burns hotter so there for it gets better penetration-Clarke 130EN-Miller MaxStar 150STL-Miller Elite 29' Roadster
Reply:IS that why flux core bruns hotter, the smaller cross sectional area?
Reply:Originally Posted by ZobmanIS that why flux core bruns hotter, the smaller cross sectional area?
Reply:Why is the sky blue, Why is water wet, it just is.  I've noticed I get way better penetration with dual shield over solid wire, never understood why, but I definitely do.  And that is running flux-core + gas, so the gas isn't cooling it.
Reply:Yup, I never felt the need for a cool hand heat shield until I started running dual shield uphill.   Then I got Nomex lined gloves AND a heat shield...and I still got burned.