Equipment for Flux Core Welding
Like shielded metal arc welding (SMAW, stick), Flux Core Welding (FCAW) is a popular welding process that uses the assistance of flux within a tubular wire to help produce high-quality welds. Unlike shielded metal arc welding, flux cored welding can be divided into two distinct processes: self-shielded flux-cored arc welding (FCAW-S) and gas-shielded flux-cored arc welding (FCAW-G).
Both the home hobbyist and professional welder will encounter situations where one process is advisable over the other. FCAW-G is most often used indoors, while FCAW-S is typically used outdoors. To maximize productivity and quality, welders should become familiar with the welding tools and equipment of both processes so that they can quickly setup and operate whichever process is best for their application and welding environment.
Gas-Shielded Flux Cored Arc Welding (FCAW-G)
As the name implies, FCAW-G requires the use of an external shielding gas contained in a cylinder to prevent porous welds. Shielding gas cylinders are bulky and the external shielding gas plume must be protected from breezes, but FCAW-G has many benefits in the production environment ranging from aesthetic welds to hard-to-beat deposition rates—sometimes even out of position.
Typically, the shielding gas cylinders used for FCAW-G are filled with either 100% carbon dioxide or argon/carbon dioxide mixtures. Always double check the filler metal’s data sheet \before welding to ensure that the shielding gas being used is of the appropriate composition for the wire being used. Different shielding gasses can be used to achieve benefits such as additional penetration or a smoother arc with reduced spatter.
In addition to the shielding gas itself, FCAW-G also requires the following equipment:
- a flowmeter which mounts to the tank to supply the appropriate flow of shielding gas
- a hose to deliver gas from the flowmeter to the wire feeder
- a welding gun (complete with a nozzle mounted to a diffuser) to deliver both wire and gas from the wire feeder to the weld
To get the most out of gas-shielded flux cored arc welding, it is useful to select a welding power source that can keep up with the productivity the process and filler metal can provide. Welders who want to maximize their pounds per hour may want to consider larger wire diameters (typically 1/16” and above). In turn, these wire diameters benefit from power sources that can output 300 or more amps at 100% duty cycle. Many of these industrial power sources have additional quality-of-life features that assist maintaining high-productivity such as trigger hold (to prevent hand cramping with those long welds) and parameter memory (to allow quick switching between in- and out-of-position welds).
Since FCAW-G is commonly used indoors, attention to ventilation is a critical safety consideration. Ventilation can be centralized through very large, fixed fume extraction systems, localized through smaller portable fume extractors. When using welding fume extractors is impractical or cannot otherwise be used, personal protective equipment such as supplied-air respirators or personal air purifying respirators (PAPRs) can be used to ensure a safe breathing atmosphere.
Self-Shielded Flux Cored Arc Welding
Self-Shielded flux cored wires can produce low- and porosity-free welds without an external shielding gas. As a result, the process is much more portable and better suited for welding outdoors “in the field”.
Working in the field often means working away from or even off the grid. This means that engine driven welding power sources are often required. Be aware that FCAW-S can be used with CC power sources, but benefits from more modern constant-voltage (CV) capable equipment. Some applications may dictate that CV equipment be used because of the benefit it has on quality and ease-of-use.
Another key piece of equipment for FCAW-S is the “suitcase” wire feeder. This wire feeder is designed to be portable while still protecting the wire from the working environment. Pay attention to the durability of the case, controls, and connections.
Insulated copper cables are required to span between the power source and both the work and wire feeder. These leads should be appropriately sized for the distance and amperage being used. Assistance in sizing welding leads can be found in power source technical documentation or from trusted welding equipment suppliers.
Fighting Voltage Drop
Longer, improperly sized, and/or damaged welding cables lead to voltage drop in the welding circuit, meaning that the voltage at the welding arc is less than the voltage selected at the welding power source. Voltage drop is problematic because self-shielded flux cored wires require that voltage be maintained within a narrow window relative to the wire feed speed being used to achieve good arc performance and proper operation of the wire’s slag system.
Fortunately, modern welding equipment from industry leaders such as Miller Electric and Lincoln Electric can sense voltage drop in the welding circuit and automatically compensate as needed so that preset voltage is maintained during welding. [See the Arc Reach Stick/TIG remote or the FX360XL with CrossLinc] It is possible to manually compensate for voltage drop using a voltmeter and some scrap steel, but the process is time consuming and must be repeated anytime that the length or quality of cabling is changed.
High Quality Welding Tools Deliver High Quality Results
The first step of achieving high-quality welds with any welding process is ensuring that the tools being used are of the highest quality. Of course, having a sharpened chipping hammer is useful for removing slag, but using a wire that produces easy-to-remove slag can further speed up the cleanup process. The tubular wires used for FCAW have a significant impact on the quality and productivity of an application: gain the best results in your welding application by selecting filler metals from industry leaders like Airgas. Source your welding consumables at an Airgas location near you.
The same can also be said of welding power sources, wire feeders, and other accessories. No matter if you are welding with FCAW-G or FCAW-S, options are available to help you make better welds in less time. Learn more about our welding rental equipment and see industry-leading equipment with benefits for both mobile welding and in-shop fabrication.
