Flux-cored wire is held on a wire spool and used with a Metal Inert Gas welder. The same welding procedures are used for both solid wire and flux-cored wire. Flux-cored wire does not rely on a shielding gas to shield the weld from contamination. This allows you to benefit from the production speed of a MIG in conditions where shielding gas would fail.
Welding with flux-cored wire requires you to change the feeder wheels, lead liner and weld tip of the MIG welder. This is due to the increased diameter of the flux-cored wire over solid wire. Additionally, the weld cup is not required when welding with flux-cored wire.
The cup located on the MIG gun is used to flow shielding gas onto the weld puddle to eliminate weld contamination and porosity. No shielding gas allows you to remove the cup from the MIG gun. Without the cup you gain greater visibility of the weld joint and the MIG gun can fit into smaller spaces.
Without shielding gas, amperage and voltage settings will need to be set precisely as Flux cored wire is less forgiving than solid core wire.
Welding with Flux Cored Wire
MIG welding techniques are the same for flux cored wire as solid core wire. The MIG gun should sit at an angle between 5 and 15 degrees, flux-cored wire requires that the angle you use remain consistent throughout the weld, even a slight deviation will cause differences in the weld.
Use the same method of welding that you would use with solid wire. Work the weld using a circular motion moving the weld puddle 1/8-inch with each rotation. As flux-cored wire welds hotter than solid wire, your voltage and amperage settings will differ from what you're used to.
Vertical Welding with Flux Core
Vertical flux-cored welding should be run uphill. When the flux-cored wire is heated, it releases the molten flux. Welding flux-core downhill can cause the flux to contaminate the weld, reducing the welds structural strength.
Holding the proper MIG gun angle of 5 to 15 degrees in important when welding with flux-cored wire as it is less forgiving then solid core wire.
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