Flux Core Welding

 

Flux core welding is a type of arc welding process that uses a tubular wire electrode with a flux core. This flux forms a protective gas shield around the weld, preventing contamination from the atmosphere.

Flux Core Arc Welding

 

Outer shield – principle of operation

Outer shield

Innershield – principle of operation

Innershield

ARC CHARACTERISTICS

 

Constant Voltage Characteristic

 

 

Flux Core Welding

FCAW – differences from MIG/MAG

 

FCAW WELDING

• usually operates in DCEP but some “Innershield” wires operate in DCEN
  • power sources need to be more powerful due to the higher currents
  • doesn’t work in deep transfer mode
  • require knurled feed rolls

Backhand drag technique

 

Advantages

#preferred method for the flat or horizontal position
#slower progression of the weld
#deeper penetration
#weld stays hot longer, easy to remove dissolved
#gasses

Disadvantages
#produce a higher weld profile
# It is difficult to follow the weld joint
#can lead to burn-through on thin sheet plates

Forehand (“push”) technique

Advantages

#a preferred method for vertical up or overhead position

arc is directed towards the unwelded joint, preheat
effect
easy to follow the weld joint and control the
penetration
Disadvantages
produce a low weld profile, with coarser ripples
fast weld progression, shallower depth of penetration
the amount of spatter can increase

FCAW advantages
• less sensitive to lack of fusion
• requires a smaller included angle compared to MMA
• high productivity
• all positional
• smooth bead surface, less danger of undercut
• basic types produce excellent toughness properties
• good control of the weld pool in positional welding especially with rutile wires
• seamless wires have no torsional strain and are free
• ease of varying the alloying constituents
• There is no need for shielding gas

FCAW disadvantages
• limited to steels and Ni-base alloys
• slag covering must be removed
• FCAW wire is more expensive on a weight basis than solid wires (exception: some high alloy steels)
• for the shielded process, the gaseous shield may be affected by winds and drafts
• more smoke and fumes are generated compared with MIG/MAG
• in the case of Innershield wires, it might be necessary to break the wire for restart (due to the high amount of insulating slag formed at the tip of the wire)

 

FCAW Advantages and Disadvantages

 

FCAW advantages disadvantages

 

Applications for FCAW 

 

• Welding structural steel in buildings and bridges
• Welding pipes and pressure vessels
• Welding automotive parts
• Welding agricultural equipment
• Welding heavy equipment

 

FCAW Advantages over other welding processes

Increased productivity: FCAW is a fast welding process, with deposition rates up to 10 times faster than manual arc welding.

Reduced costs: FCAW is a relatively low-cost welding process, as it does not require the use of shielding gas.

Improved weld quality: FCAW produces high-quality welds with good penetration and minimal spatter.

Versatility: FCAW can be used to weld a wide variety of metals, including steel, stainless steel, and aluminum.