3 | LEARNING TO WELD | 3 |
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SELF-SHIELDED FCAW (FLUX CORE ARC WELDING)
Figure 3 illustrates the action taking place in the self- shielded FCAW (Innershield) welding arc. It closely resembles what is actually seen while welding.
FIGURE 3
After running a weld bead, the slag may be removed with a chipping hammer and wire brush. This improves appearance and allows for inspection of the finished weld.
Since machine size and output characteristics limit the size and type of wire electrode which can be used, check your Instruction Manual “Application Chart” or see the
DRAG TECHNIQUE
Cored Wire
Protective Slag
Weld Metal
Burning of core materials inside the wire electrode provides a gas to shield the molten metal as it solidifies.
Arc Stream
Weld Puddle
DIRECTION OF TRAVEL
Application Guide on the inside door of the Machine. This will give you the proper electrode size and control set- tings to be used.
GMAW (GAS METAL ARC WELDING)
Figure 4 illustrates the GMAW (Also referred to as MIG) welding arc. Solid wire does not contain fluxes or ingredi- ents to form its own shielding and no slag forms to pro- tect the molten weld metal. For this reason, a continuous even flow of shielding gas is needed to protect the molten weld metal from atmospheric contaminant’s such
The “arc stream” is seen in the middle of the picture. This is the electric arc created by the electric current flowing through the space between the end of the wire electrode and the base metal. The temperature of this arc is about 6000°F, which is more than enough to melt metal.
WARNING
The arc is very bright, as well as hot, and cannot be looked at with the naked eye without risking painful injury. A very dark lens, specifically designed for arc welding, must be used with the hand or face shield whenever viewing the arc .(ANSI
The arc melts the base metal and actually digs into it much as water through a nozzle on a garden hose digs into the earth. The molten metal forms a molten pool or crater and tends to flow away from the arc. As it moves away from the arc, it cools and solidifies.
The function of the Innershield cored wire electrode is much more than simply to carry current to the arc. The wire core is composed of fluxes and/or alloying ingre- dients around which a steel sheath has been formed. It is simply a stick electrode turned inside out in a con- tinuous wire form.
The cored wire melts in the arc and tiny droplets of molten metal shoot across the arc into the molten pool. The wire sheath provides additional filler metal for the joint to fill the groove or gap between the two pieces of base metal.
The core materials also melt or burn in the arc and perform several functions. They make the arc stead- ier, provide a shield of
as oxygen and nitrogen. Shielding gas is supplied through the gun and cable assembly, through the gas nozzle and into the welding zone.
FIGURE 4
PUSH TECHNIQUE
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| Gas nozzle | |
Solid wire |
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| Shielding gas | |
electrode |
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| Weld metal | ||
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Base metal |
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| DIRECTION OF TRAVEL | |
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Important!
The MIG welding process requires that the welder has a gas solenoid valve installed in order to control the flow of the shielding gas. Read your Operators Manual to see if your machine requires additional items to MIG weld.
When comparing the GMAW and FCAW processes, you can see that the principal difference between the two lies in the type of shielding used. GMAW uses gas for shield- ing, thus we have Gas Metal Arc Welding. FCAW uses the melting or burning of the core ingredients for shield- ing, and is thus termed
The recommended LINCOLN Super Arc