Flux Cored Welding
Flux-cored welding, formally flux-cored arc welding (FCAW), is an arc-welding process using a continuously fed tubular consumable electrode filled with flux. The arc melts wire and base metal while flux generates shielding gas and forms slag. It runs self-shielded without external gas or gas-shielded with supplementary shielding, offering high deposition and tolerance for outdoor or drafty conditions.
On the shop floor, flux-cored welding is the process reached for when thick plate or structural sections need heavy weld buildup and the job has to keep moving even under drafts. In a fabrication cell, a constant-voltage power source and wire feeder are paired with the correct flux-core wire, polarity, and shielding setup. Structural frames, machine bases, heavy guards, and jigs are common workpieces, where productivity and penetration matter more than bead cosmetics. In CNC-adjacent shops, welded machine frames and fixtures are of particular concern because the heat input and weld shrinkage change the material; weldments often have to be allowed to cool or be stress-relieved before the final machining pass to hold dimensional tolerance. Operators must also remove slag between passes on multipass welds to avoid inclusions that can later show up as defects in finished components.
What is the difference between FCAW and solid-wire MIG welding?
MIG welding, or GMAW, uses a solid wire electrode with an external shielding gas. Flux-cored welding uses a flux-filled tubular wire, and shielding can come from the flux alone, from external gas, or from a combination of both.
Does flux-cored welding always require shielding gas?
No. Self-shielded FCAW relies entirely on the flux core to generate shielding and protect the weld pool. Gas-shielded FCAW, often called dual-shield, uses external shielding gas in addition to the flux.
Why is flux-cored welding used on thicker steel?
FCAW provides high deposition rates and good penetration, making it efficient for heavy plate, structural steel, and thick-section fabrication. It also handles surface conditions and outdoor drafts better than many solid-wire processes.