GMAW, FCAW & SAW Flashcards
Self-shielded FCAW uses shielding gas from:
A) the base metal
B) an external source
C) the flux
D) a paste flux applied to the base metal before welding
C) the flux
Describe the operating principles of FCAW.
FCAW uses an arc established between a continuously fed electrode & the work piece. Appropriate settings made by the operator maintain a constant burn off rate of the electrode. Depending on the power source & the wire drive system used, the arc length is maintained automatically. Shielding gas can be applied externally &/or obtained from flux contained within the hollow electrode core (depending on the flux wire being used).
What is the electrode extension range for self shielded FCAW?
For self-shielded electrodes, extensions range from 3/4 - 3- 3/4” (19-95mm).
List the components of a basic FCAW applications?
Welding power source Wire feeder compatible with the power source Welding gun & cable assembly Spooled filler wire Shielding filler wire Shielding gas (gas controlled equipment) Flux feed & recovery equipment Cooling system
What type of power source is used for most FCAW applications?
A) CV
B) CC
C) ACHF
D) AC square wave
A) CV
Explain the differences between the automatic and semi-automatic operating mode with FCAW.
Semi-automatic - the arc to be manually directed to the joint to be welded
Automatic - the arc is directed or positioned to the joint by mechanical means
What shielding gases are most often used with FCAW?
A) helium & argon
B) co2 & argon/hydrogen gas mixes
C) co2 & nitrogen
D) co2 & argon/co2 gas mixes
D) co2 & argon/co2 gas mixes
What duty cycle rating is common for semi-automatic welding shop FCAW power sources?
A) 20%
B) 60%
C) 80%
D) 100%
B) 60%
What type of power source are constant speed wire feeders mainly used with?
A) CV
B) CC
C) inverter design
D) CC motor generator sets
A) CV
Voltage-sensing wire feeders set their speed according to:
A) open circuit voltage
B) primary input power voltage
C) arc voltage
D) inductance
C) arc voltage
What type of drive roll design is preferred for FCAW wires?
A) v-groove
B) u- groove
C) knurled
D) angled
C) knurled
Explain the purpose of the curved neck design FCAW gun.
To maximize operator comfort in the semi automatic welding mode, it helps the wire solid contact against the inside of the contact tip, ensuring a positive & continuous transfer of current to the wire
How are FCAW guns rated?
A) by current-carrying capacity
B) by maximum open circuit voltage
C) by maximum wire size
D) by gas nozzle size
A) by current-carrying capacity
One of the main functions of the contact tube is to:
A) direct the shielding gas over the weld zone
B) transfer current to the electrode
C) contact the base metal to enable arc initiation
D) insulate the wire electrode from the gas nozzle
B) transfer current to the electrode
Why is the gas nozzle insulated? Explain your answer.
A sleeve of insulating material is usually placed inside the nozzle to prevent contact between the nozzle & the wire. If the nozzle were electrically live & should touch the work, it tends to arc & hang up on the work. This would interfere with gun movements cause the nozzle damage & leave harmful stray arcs on the work surface.
What type of liner is recommended for FCAW wires?
A) telfon
B) nylon
C) copper alloy
D) steel
D) steel
What controls arc length with FCAW?
A) amperage
B) voltage
C) electrode extension
D) arc force
B) voltage
How is voltage controlled on most CC power source?
Voltage on most CC machines are pre-set or may have a range switch or separate cable attachment lugs to step the OCV (open circuit voltage) up or down.
What is the advantage of using DCEN with FCAW?
A) arc is more stable
B) requires less shielding gas
C) good for welding light gauge sheet metal
D) doubles the duty cycle rating of CV power sources
C) good for welding light gauge sheet metal
Electrode extension is defined as:
A) the distance between the end of the electrode and the weld metal
B) the distance between the contact tube and the end of the wire electrode
C) the distance between the gas nozzle and the work
D) the distance between the contact tube and the work
B) the distance between the contact tube and the end of the wire electrode
What is the recommended electrode extension for gas shielded FCAW using 1.2mm (0.045”) wire in the flat position.
A) 10mm - 19mm (3/8” to 3/4”)
B) 13mm - 25mm (1/2” to 1”)
C) 19mm - 32mm (3/4” to 1-1/4”)
D) 38mm - 76mm (1-1/2” to 3”)
A) 10mm - 19mm (3/8” to 3/4”)
What is the advantage of using 75% argon/25% CO2 gas mix on carbon steel?
A) lower penetration
B) deeper penetration
C) improved arc characteristics
D) argon is less dangerous when used in confined spaces
C) improved arc characteristics
Name (4) factors that can influence gas flow rates.
1) __________
2) __________
3) __________
4) __________
1) the type of shielding gas used
2) type of thickness of material
3) position of welding
4) joint design
Explain the terms cast and helix.
Cast - a circle formed by one wrap when laid on the floor
Helix - the spacing that forms between 2 un-restricted loops of wire. This gives a measure of twist that is inherent in the wire.
The mode of metal weld transfer with basic type core wires is:
A) spray
B) short circuit
C) globular
D) pulsed spray
C) globular
What are the primary functions of the flux in FCAW wires?
Provides deoxiders/scavengers to remove impurities
Forms a slag cover to protect the weld metal from atmospheric contamination & controls the shape and appearance of the weld bead
Acts as an arc stabilizer by providing an electrical path which results in a stable arc, less spatter & uniform weld bead
Adds alloying elements to provide the mechanical, metallurgical & corrosive resistance properties
Provides shielding gas to displace atmospheric air
Explain the following FCAW wire classification: E491T-9CH
E \_\_\_\_\_\_\_\_\_\_ 49 \_\_\_\_\_\_\_\_\_\_ 1 \_\_\_\_\_\_\_\_\_\_ T \_\_\_\_\_\_\_\_\_\_ 9 \_\_\_\_\_\_\_\_\_\_ CH\_\_\_\_\_\_\_\_\_\_
E = electrode 49 = tensile strength in Megapascals x 10 1 = all position application T = tubular wire 9 = slag system, current, polarity, shielding gas CH = controlled hydrogen
What does the G stand for in the CSA FCAW electrode classification E492T-G?
A) gas shielded
B) general classification for electrodes mot covered under any other classification
C) for use on class G secondary containment vessels for nuclear service
D) general purpose electrode for use on carbon and low-alloy steels
B) general classification for electrodes mot covered under any other classification
Name (2) FCAW wires that can be used without external gas shielding.
EXXXT -3 EXXXT -4 EXXXT -6 EXXXT -10 EXXXT -11 EXXXT -13 EXXXT -14
One of the main advantages of metal core wires is:
A) lower cost than flux core wires
B) no external shielding gas is required
C) designed for use on conventional CC power sources
D) high deposition rates
D) high deposition rates
What part of FCAW equipment requires the most ongoing maintenance?
A) power source
B) gas solenoid
C) gun & cable assembly
D) wire feeder drive motor
C) gun & cable assembly
Name (3) causes of porosity with FCAW.
1) ___________
2) ___________
3) ___________
1) lack of shielding gas
2) improper gun inclination
3) air drafts
Name (3) advantages and (3) disadvantages of FCAW
Advantages
1) __________
2) __________
3) __________
Disadvantages
1) __________
2) __________
3) __________
Advantages
1) up to 4 times greater deposition rate than SMAW
2) high operator factor - easily mechanized
3) visible arc - easy to use
Disadvantages
1) equipment more expensive than SMAW
2) more smoke & fumes requiring exhaust removal equipment
3) wire feeder must be in close proximity to welding
