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Flux-cored wire
From GAWDAwiki
Flux-cored wire is a composite tubular filler metal electrode consisting of a metal sheath and a core of various powdered materials, producing an extensive slag cover on the face of a weld bead. External shielding may be required.[1]
There are two types of flux cored wires: gas shielded and self-shielded. Gas shielded flux cored wires require external shielding gas and the slag is easy to remove. The operator may want to consider using gas shielded flux-cored wires when welding on thicker metals or in out-of-position applications. Gas shielded flux-cored wires have a flux coating that solidifies more quickly than the molten weld material. As a result, it creates a "shelf" to hold the molten pool when welding overhead or vertically up. Self-shielding flux-cored wire does not require external shielding gas; the weld pool is protected by gas generated when flux from the wire is burned. As a result, self-shielding flux-cored wire is more portable because it does not require an external gas tank.[2]
Flux cored wire is a type of wire or consumable electrode used for MIG welding (also known as GMAW) with flux on the inside of the wire. The flux protects the weld by becoming a top layer when the filler metal melts during the welding process. The flux is then chipped away. There are two kinds of flux cored wires: self-shielded and gas shielded. The self-shielded flux cored wire produces a gas as it melts that protects the weld and also leaves a protective layer on top of the weld joint.
The wire used for MIG welding is a consumable electrode that melts during the welding process and fills the weld gap. Solid wire without flux needs a shielding gas, such as a mixture of 75 percent Argon and 25 percent CO2, in order to protect the weld joint from contamination.
Self-Shielding Flux Cored Wire
Whether MIG welding outdoors where wind can blow away shielding gas or moving a MIG welder from one location to another, flux cored wire makes MIG welding outdoors and in multiple locations easier by eliminating the need for shielding gas. Besides portability, flux cored wire also eliminates the expense of purchasing and refilling gas cylinders-one of the highest ongoing expenses for MIG welding.
The flux and spatter produced by flux cored MIG wire means that there will be considerable clean up when done welding. The appearance of the weld will suffer as a result.
Gas Shielded Flux Cored Wire
For the greatest amount of weld protection, gas shielded flux cored wires leave a layer of slag on top of the weld joint. However, the shielding gas makes the slag easier to remove. This kind of MIG wire is especially useful when welding thicker metals or for welding in overhead or awkward positions. The flux coating solidifies faster than the weld and holds overhead or vertical welds in position.
Though self-shield flux cored wire requires the additional expense of shielding gas, it also allows welders to work with metals that aren't completely clean and provides significant penetration into weld joints.
MIG Wire Thickness
Most welder manuals will specify which wires are best for a particular job, the most common MIG wires typically fall into the following range of thickness: .023, .030, .035, and .045. Larger projects, especially industrial ones, may require a thicker wire, but these are the first ones to consider for most projects.
MIG welding has its own classification system for wire electrodes that can be illustrated in the following example for ER 70S-6:
- ER: Electrode or filler rod for MIG or TIG welding.
- 70: 70,000 pounds minimum of tensile strength for each square inch of weld.
- S: Solid wire.
- 6: Amount of deoxidizing and cleansing agent on electrode.
The best wire for the job will depend on the type of metal, the location of the work, and the importance of appearance. Solid wire, flux cored self-shielding wire, and flux cored gas shielded wire are all effective wires for MIG welding.
