Flux Core Arc Welding (FCAW) Advantages & Disadvantages

Marty Rice is a welding instructor at a high school career center in Texas. He is the author of Arc Welding 101, which appears in each issue of Practical Welding Today®, and is an honorary member of the Iron Workers Local 263.

Advantages
When using FCAW, a welder does not have to stop and change rods as in SMAW. That means longer beads with fewer restarts, high weld deposit, and more production. This means less chance of defects in the restart area.
The process uses DCEP and produces deep fusion with a good weld appearance. In addition, smaller-diameter wires can be used in all positions.
FCAW can be used with or without shielding gas; if you use shielding gas, carbon dioxide is very cheap. (Other gases, such as 75/25, also can be used.) The flux contains oxidizers, so the base metal needs minimum cleaning before a weld is made. Postweld cleanup is a breeze because the slag chips off very easily.
On top of that, the wire stickout with FCAW is a lot longer than with GMAW (about ½ to ¾ inch), so welders can see and control the puddle much better. It couldn't be any better if it welded itself--which it can if it is set up for automatic welding. I usually can have a student welding satisfactorily the first day with FCAW (and GMAW, for that matter)

Disadvantages
Fumes! FCAW puts out more smoke than a Houston barbecue joint. If you are using FCAW in a shop, you really should have a strong point-of-contact ventilation system. If not, your lungs are going to be full of welding fumes, and that just isn't healthy.
Other than the fumes, the only other disadvantage is that FCAW usually is used only on mild steel. It has limited uses for cast iron and stainless, but mild steel is all I've ever seen it used on.
In the Field
The only time I used FCAW in the field was on column splices in which one column was stacked on the one below it. This arrangement uses gusset plates where the bolts are attached, and the column itself is beveled for a groove weld.
The included angle (the sum of both column angles where the beveled edges meet) usually is very wide, which leaves a large amount of welding to be done. These are zero-defect welds that are X-rayed for soundness. Stick welding takes entirely too long for these angles and requires too many restarts, which increase the chance of defects.
With FCAW, one welder sits in a basket on one side of the column while another welds the opposite side. This puts the same amount of heat on each side, eliminating any distortion. It makes for good, continuous beads with little time lost. And in construction, time equals money.