FLUX CORED ARC WELDING FCAW Definition A consumable

* FLUX CORED ARC WELDING (FCAW) Definition: A consumable fusion welding process where an arc is created between a continuously fed, flux filled tubular wire and the grounded base metal. Atmospheric shielding of the molten weld puddle is provided completely or in part by the flux that is contained within the tubular electrode. Shielding gas may be used to supplement the atmospheric shielding of the molten weld puddle.

Types of FCAW: There are two distinct FCAW processes. Self Shielding FCAW (no shielding gas required) Dual-Shield (external shielding gas must be used)

Equipment Requirements: The equipment requirements for the FCAW process are the same as those for the GMAW process. -Constant potential/voltage (CP or CV) power source up to 1000 amperes) -Combination wire conduit and power cable (water cooled for some applications) -Shielding gas supply and equipment -Ground cable and clamp

Advantages of the FCAW Process: -High deposition rates. Deposition rates of up to 25 lbs. per hour can be achieved. -Minimum electrode waste. Up to 95% of electrode use is attainable. -Narrow groove angle. The deeper penetration of the FCAW process can eliminate the need to bevel plates up to ½ in thickness. -Minimum pre-weld cleaning. The addition of deoxidizers allows high quality welds created on plates with light surface oxides and mill scale. -High quality all position welding. -Flexibility. Changes to the power source setting allow for welding different thicknesses using the same electrode diameter. -Alloying elements and deoxidizers can be added to the weld puddle. -Excellent weld puddle control.

Limitations of the FCAW process: -Electrodes limited to ferrous and nickel based alloys. -Higher electrode and equipment costs. Higher costs quickly recovered due to increased productivity. -Post welding cleaning required before finishing (slag). -Increased smoke due to the combustion of flux.

Flux used with the FCAW process: -The flux used in the FCAW process serve the same function as the flux used in the SMAW electrodes. The fluxes used with the FCAW process are mainly lime and rutile based and provides the following advantages: -Deoxidizing agents aid in cleaning the weld puddle. -Slag formers help slow the cooling rate of the weld and can aid in the formation of the finished weld bead shape. -Fluxing agents aid in the flowing of the weld puddle to combat undercutting. -Alloying elements can be added to the flux. -Shielding gas to protect or aid in the protection of the molten weld puddle.

Welding Variables: -The welding variables used with the FCAW process are very much the same as those used with the GMAW process, with the following exceptions: -Stick-out distance: Because the electrodes used with the FCAW process tend to be larger than those used with the GMAW process, stick-out distances are longer. Typical electrode extensions for gas shielded FCAWE electrodes will range from ¼ to 1 ½ inches depending on the diameter of the electrode. The electrode extension used for self shielding electrodes will range from 1/8 to 4 ½ inches depending on the electrode diameter. The longer electrode extension used for self shielding electrodes allow the electrode to properly preheat before it reaches the welding arc.

-Direction of welding: -With. 045 and smaller FCAW electrodes, welding can be done using a forehand or backhand technique. -However, a backhand or trailing technique is recommended for all FCAW electrodes. -A drag angle of 2 to 15 degrees is recommended. -Use of a drag or trailing technique allows the welding operator a better view of the weld puddle and yields deeper weld penetration.