Flux cored arc welding has several advantages over other commonly used welding processes such as SMAW, GMAW, and GTAW. This article discusses a few of those advantages. At the end, a few disadvantages of this process have also been discussed.
The main advantage of flux-cored arc welding process over GTAW and SMAW is its’ higher deposition rate. The FCAW wire is continuously fed through a mechanised arrangement, while the filler in SMAW and GTAW is manually fed. So, naturally – the rate of deposition of metal in FCAW is higher.
Another main advantage of FCAW over gas metal arc welding (GMAW) and gas tungsten arc welding (GTAW) – both these processes use a solid bare rod as a filler – is that some of the alloying content can be added through flux as well. In GTAW and GMAW, the entire chemistry must be contained into the wire. For this, sourcing a suitable wire becomes sometimes difficult. Also, a wire loaded with chemistry is expensive as well.
On the other hand, in a fcaw wire – the desired chemistry can be introduced through the flux as well. The consumable manufacturer simply needs to use the right metal powders in the right proportion to achieve the specified chemistry in weld metal. This makes the ultimate filler wire cheaper.
The surface finish of the bead deposited with flux-cored arc welding is quite high as well.
Most mild steels used for structural and construction applications can be welded satisfactorily with FCAW, without use of carbon dioxide as a shielding gas. For these welds, although the strength is high, the ductility of the weld is slightly low in comparison to when CO2 is used as shielding gas.
The introduction of CO2 as the shielding gas in FCAW improves the properties of the weld. The ductility of the weld is higher, porosity is reduced, and penetration of the weld is greater.
The spatter in flux-cored arc welding is lesser in comparison to gas metal arc welding.
The process has higher tolerance for dust and scale on the base metal than other processes.
Faster welding speeds are observed in FCAW.
The process can function fairly well without shielding gas. This lowers the need to source a gas cylinder, which is sometimes difficult. Absence of shielding gas makes the equipment simple, and easier to carry around as well.
Using smaller diameter wires, welding can be done in all positions using this process.
The wire-feed arrangement in FCAW is a mechanised process. The motor driven arrangement pulls the wire from the spool and feeds to the welding gun. The movement of welding gun along the direction of welding is generally done by the welder (hence this process is called semi-automatic welding process). Since the wire is fed continuously, little time is wasted in changing the electrodes.
No stub is left behind after the welding in this process, unlike in SMAW process. Hence wastage of metal is far lower.
Flux-Cored Arc Welding Disadvantages
Besides the advantages, flux-cored arc welding comes with a few disadvantages as well.
One of the disadvantages is that fcaw wires (of mild steel and low alloy grades) are sensitive to changes in welding conditions. This sensitivity, called voltage tolerance, is not as much in SMAW welding. During the welding, there may be voltage fluctuations due to change in the arc gap. These changes in the arc gap may be due to the profile of the job, or due to shaking in the welder’s hand. When the voltage fluctuates, the arc is not so smooth.
This voltage sensitivity can be reduced by use of a shielding gas. Also, this problem is reduced when slag forming elements are increased in the flux-core of the wire.
In order to maintain a constant voltage at the arc, a constant speed wire-feeder mechanism and a constant voltage power source are necessary.
So these were a few of the flux-cored arc welding advantages and disadvantages. Please share your thoughts in the comments section below.