Flux Cored Arc Welding (FCAW) WIT Pg. 3-14 & Fig. 3.16 Instructor Should Explain: Similar to GMAW, Except: Tubular Electrode Flux Process Shielding Gas Optional

Objective: SWBAT to identify and describe the FCAW process.

Trade Terms Arc- In Welding the electric arc is produced when the welding current is forced to jump a gap and pass through the air. The air has a high resistance to electrical flow causing the high temperatures, in excess of 10,000 degrees F, need to melt the base materials. Flux-The role of a flux in joining processes is typically dual: dissolving of the oxides on the metal surface, which facilitates wetting by molten metal, and acting as an oxygen barrier by coating the hot surface, preventing its oxidation.

Trade Terms Shielding- In welding shielding is the act of protecting the molten weld metal from atmospheric contamination. Shielding can be achieved by a shielding gas or by a flux. Electrode- In arc welding an electrode is used to conduct current through a work piece to fuse two pieces together. In FCAW the electrode is consumed as part of the completed weld.

The Flux Cored Arc Welding Process As defined by the American Welding Society (AWS), flux cored arc welding (FCAW) is an electric arc welding process that fuses metallic parts by heating them with an arc between a continuously fed, consumable, flux cored electrode and the work. Primary shielding for the molten weld metal is obtained from the fluxing ingredients within the tubular electrode that are deposited as slag on top of the weld. The flux cored electrode may be supplemented by an external shielding gas.

Self-Shielded FCAW WIT Pg. 3-14 & Fig. 3.16 Instructor Should Explain: Talk About Each of the Items Listed on Figure

FCAW Process Types There are two process types used for the deposition of metal. Self Shielded – All of the fluxing ingredients required for the proper transfer of the filler material and shielding of the molten pool are included in the core material. Gas Shielded – A shielding gas is used in addition to the shielding from the flux core. Carbon dioxide (CO2) can be used alone or with Argon (Ar) in a specified mixture to shield the molten weld metal from outside atmosphere.

Modes of operation FCAW can be done in one of two ways. Semi-automatic- where the weld is made using FCAW equipment and a manual welding gun. Automatic- The weld is made using specialized equipment and controls that are monitored by the machine operator.

FCAW Equipment Power Supply The power supply provides the welding current needed to melt the base metal and the electrode. FCAW uses two types of welding current. Direct Current Electrode Negative (DCEN) for self shielded FCAW Direct Current Electrode Positive (DCEP) for gas shielded FCAW

FCAW Equipment Wire Feeder The wire feeder is the device that feeds the required amount of filler material at a fixed rate of speed throughout the welding operation.

FCAW Equipment Guns The gun is held by the welder during the welding operation. It is at the tip of the gun where the electrical current is transferred to the filler material. The gun trigger controls the start and stop operation of the machine. WIT Pg. 3-15 & Fig. 3.18 Instructor Should Explain: Note the Hand Shield on the Self-Shielded Gun Self-Shielded Uses Higher Currents, More Heat Gas Shielding Helps Cool Operation

Gas-Shielded FCAW Equipment WIT Pg. 3-15 & Fig. 3.19 Instructor Should Explain: Talk About Each Item Shown in Figure: Shielding Gas Supply Shielding Gas Regulator Electrode Supply Power Source Electrode Feed Unit Welding Gun Cable Assembly Power Supply and Controls Workpiece Cable Workpiece Clamp Wire Feed Units Have Two Types: - Voltage Sensing - Constant Feed

Self-Shielded FCAW Equipment WIT Pg. 3-16 & 3.19 (Cont) Instructor Should Explain: Only Difference Is the Gun and the Pinch Rollers

FCAW Advantages High productivity Deep penetration High quality welds All position welding Tolerates contamination better than GMAW More suitable for field work than GMAW Combines the advantages of SMAW (good shielding) and GMAW (high productivity) WIT Pg. 3-16 Instructor Should Explain: Discuss Advantage Listed

FCAW Disadvantages Slag to contend with during welding Slag removal Smoky process (esp. self shielded) Electrode cost Equipment complexity WIT Pg. 3-16 Instructor Should: Discuss Limitation Listed

FCAW Discontinuities Slag inclusions Porosity Incomplete fusion Incomplete joint penetration WIT Pg. 3-16, 3-17 Instructor Should: Discuss Each Item Listed

FCAW Applications General fabrication of steel and stainless steel Structural steel fabrication Pressure vessels for gasses and liquids Heavy equipment fabrication and repair Surfacing components to protect against wear. Hardfacing Maintenance and repair WIT Pg. 3-16 Instructor Should: Discuss Limitation Listed

Review Questions

FCAW Electrode Classification System Electrode E X X T - X FCAW Electrode Classification System Electrode WIT Pg. 3-15 Instructor Should Explain: “E” = Electrode - Current Carrying

E X X T - X FCAW Electrode Classification System Minimum Specified Tensile Strength WIT Pg. 3-15 Instructor Should Explain: Strengths Are in 10’s of Thousands

FCAW Electrode Classification System Welding Position(s) E X X T - X FCAW Electrode Classification System Welding Position(s) WIT Pg. 3-15 Instructor Should Explain: 1 = All Positions 0 = Flat Grooves, Fillets & Horizontal Fillets

FCAW Electrode Classification System Tubular E X X T - X FCAW Electrode Classification System Tubular WIT Pg. 3-15 Instructor Should Explain: Rolled Strip Mechanical Seam Flux Filled Protect From Moisture

E X X T - X FCAW Electrode Classification System Chemical Composition Operating Characteristics WIT Pg. 3-15 Instructor Should Explain: Self-Shielded - 3, 4, 6, 7, 8, 10, 11 Requires Gas - 1, 2, 5 G - Multipass GS - Single Pass

Typical FCAW Classification E71T-1

Stainless Steel Electrodes Typical Applications E308T-X - Welding 304 Base Metal E308LT-X - Welding 304 or 304L Base Metal E316T-X - Welding 316 Base Metal E316LT-X - Welding 316 or 316L Base metal E309T-X - Welding Stainless to Carbon For Stainless FCAW Electrodes, the “X” Indicates the Type of Gas Shielding

How Do They Make FCAW Wires