Flux-Core Arc Welding (FCAW)

FLUX-CORE ARC WELDING (FCAW)

The Process:-

Flux-core arc welding (FCAW) is similar to GMAW, as shown in Figure a. However, as shown in Figure b, the wire electrode is flux cored rather than solid; that is, the electrode is a metal tube with flux wrapped inside. The functions of the flux are similar to those of the electrode covering in SMAW, including protecting the molten metal from air. The use of additional shielding gas is optional.

Flux-Core Arc Welding (FCAW) (a) overall process (b) welding area enlarged

Advantages of FCAW:-

High deposition rates
Deeper penetration than SMAW
High quality welds
Less pre-cleaning than GMAW
Slag covering helps with out-of-position welds
Self-shielded FCAW is draft tolerant

Disadvantages of FCAW:-

Slag must be removed
Higher fume generation than GMAW and SAW
Spatter
Equipment is more expensive and complex than SMAW
FCAW wire is more expensive

Types of continuous wire electrodes:-

Comments

Electroslag Welding (ESW)

ELECTROSLAG WELDING The Process :- Electroslag welding (ESW) is a process that melts and joins metals by heating them with a pool of molten slag held between the metals and continuously feeding a filler wire electrode into it, as shown in Figure. The weld pool is covered with molten slag and moves upward as welding progresses. A pair of water-cooled copper shoes, one in the front of the workpiece and one behind it, keeps the weld pool and the molten slag from breaking out. Similar to SAW , the molten slag in ESW protects the weld metal from air and refines it. Strictly speaking, however, ESW is not an arc welding process, because the arc exists only during the initiation period of the process, that is, when the arc heats up the flux and melts it. The arc is then extinguished, and the resistance heating generated by the electric current passing through the slag keeps it molten. In order to make heating more uniform, the electrode is often oscillated, especially when welding thicker...

Gas–Tungsten arc welding (GTAW)

GTAW The Process Gas–tungsten arc welding (GTAW) is a process that melts and joins metals by heating them with an arc established between a non consumable tungsten electrode and the metals, as shown in Figure. The torch holding the tungsten electrode is connected to a shielding gas cylinder as well as one terminal of the power source, as shown in Figure a . The tungsten electrode is usually in contact with a water-cooled copper tube, called the contact tube, as shown in Figure b , which is connected to the welding cable (cable 1) from the terminal. This allows both the welding current from the power source to enter the electrode and the electrode to be cooled to prevent overheating.The workpiece is connected to the other terminal of the power source through a different cable (cable 2). The shielding gas goes through the torch body and is directed by a nozzle toward the weld pool to protect it from the air. Protection fro...

Plasma Arc Welding (PAW)

PLASMA ARC WELDING The Process:- Plasma arc welding (PAW) is an arc welding process that melts and joins metals by heating them with a constricted arc established between a tungsten electrode and the metals, as shown in Figure 1. It is similar to GTAW , but an orifice gas as well as a shielding gas is used. As shown in Figure 2, the arc in PAW is constricted or collimated because of the converging action of the orifice gas nozzle, and the arc expands only slightly with increasing arc length. Direct-current electrode negative is normally used, but a special variable polarity PAW machine has been developed for welding aluminium, where the presence of aluminium oxide films prevents a keyhole from being established. Fig-1 Plasma arc welding: (a) overall process; (b) welding area enlarged and shown with key holing. Arc Initiation:- The tungsten electrode sticks out of the shielding gas nozzle in GTAW (Figure 1b) while it is recessed in the orifice gas nozzle in PAW (Figure...

Welding

Search This Blog