Welding Processes: A Closer Look at FCAWJanuary 29, 2015
A good industrial fabrication company will be able to offer a full range of welding processes so that the best process can be chosen for a given application. However, by far one of the most useful and frequently used welding processes is FCAW. FCAW has some outstanding advantages and capabilities; however, it also has some disadvantages and limitations and it isn’t suitable for all applications.
What Is FCAW?FCAW is the term used to refer to Flux-Cored Arc Welding. It is a semi-automatic or automatic welding process that utilizes a continuously-fed tubular electrode that contains a flux. Thus the electrode is “flux cored.” The flux contains mineral compounds and powdered metals, which produce a protective slag over the welding bead. This in turn helps to protect the quality and finish of the weld. FCAW is similar to MIG welding, or GMAW, and also to stick welding, or SMAW. However, because FCAW uses a continuously fed electrode there is no need to make frequent restarts, which in turn helps lower the chances of a defect and produces a more uniform weld. The continuous nature of the welding also allows for higher productivity. There are two main types of flux-cored welding: No Shielding Gas - The flux-cored electrode used in FCAW generates its own protective gas to shield the weld. Thus FCAW can often be performed with no additional shielding gas whatsoever without a compromise in weld quality. This eliminates the cost and setup associated with a separate shielding gas system. FCAW without shielding gas is particularly effective for thinner, flat-position metals. The lack of a shielding gas also allows this process to be effective in outdoor or windy environments that would dissipate a shielding gas. With Shielding Gas - For welding on thicker, out-of-position metals, especially structural steel welding, FCAW may be used with a shielding gas for greater quality and consistency. This is often known as “duel shield” welding since both the shielding gas and the flux are being used to shield the weld. This processes is better used in a controlled environment such as a fabrication shop where wind will not interfere with the shielding gas. The shielding gas is commonly carbon dioxide (CO2) or an argon-carbon dioxide mixture such as C-25 which contains 75% argon and 25% carbon dioxide.
The Advantages of FCAWThere are several excellent advantages to FCAW that make it a very popular choice for welding. These include:
- Yields high quality, consistent welds with fewer defects
- A high deposition rate, which is the speed that the filler metal is applied.
- Can be used in all positions with the right filler metal.
- Suitable for outdoor welding or shop welding.
- Relatively easy to learn compared to other welding processes.
- More forgiving of rust, scale, and other base metal contaminants.
- The welding arc has good visibility.
- Provides excellent weld penetration.
- Allows for high welding productivity.
The Disadvantages of FCAWHowever, despite FCAW’s many excellent advantages there are also some disadvantages. These include:
- A high level of noxious fumes which must be ventilated.
- Higher electrode wire cost compared to solid electrode wires.
- More costly equipment than many other welding processes.
- Less portable equipment than SMAW or GTAW.
- The slag covering the weld must be removed.
- Mechanical problems can lead to melted contact tips, irregular wire feed, or porosity of the weld.
- Not well-suited to all metal types.