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Flux Cored Arc Welding (FCAW) > GMAW, FCAW & SAW > Flashcards

GMAW, FCAW & SAW Flashcards

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0
Q

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

A

C) the flux

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1
Q

Describe the operating principles of FCAW.

A

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).

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2
Q

What is the electrode extension range for self shielded FCAW?

A

For self-shielded electrodes, extensions range from 3/4 - 3- 3/4” (19-95mm).

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3
Q

List the components of a basic FCAW applications?

A 
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
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4
Q

What type of power source is used for most FCAW applications?

A) CV
B) CC
C) ACHF
D) AC square wave

A

A) CV

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5
Q

Explain the differences between the automatic and semi-automatic operating mode with FCAW.

A

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

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6
Q

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

A

D) co2 & argon/co2 gas mixes

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7
Q

What duty cycle rating is common for semi-automatic welding shop FCAW power sources?

A) 20%
B) 60%
C) 80%
D) 100%

A

B) 60%

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8
Q

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

A) CV

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9
Q

Voltage-sensing wire feeders set their speed according to:

A) open circuit voltage
B) primary input power voltage
C) arc voltage
D) inductance

A

C) arc voltage

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10
Q

What type of drive roll design is preferred for FCAW wires?

A) v-groove
B) u- groove
C) knurled
D) angled

A

C) knurled

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11
Q

Explain the purpose of the curved neck design FCAW gun.

A

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

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12
Q

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

A) by current-carrying capacity

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13
Q

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

A

B) transfer current to the electrode

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14
Q

Why is the gas nozzle insulated? Explain your answer.

A

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.

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15
Q

What type of liner is recommended for FCAW wires?

A) telfon
B) nylon
C) copper alloy
D) steel

A

D) steel

16
Q

What controls arc length with FCAW?

A) amperage
B) voltage
C) electrode extension
D) arc force

A

B) voltage

17
Q

How is voltage controlled on most CC power source?

A

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.

18
Q

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

A

C) good for welding light gauge sheet metal

19
Q

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

A

B) the distance between the contact tube and the end of the wire electrode

20
Q

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

A) 10mm - 19mm (3/8” to 3/4”)

21
Q

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

A

C) improved arc characteristics

22
Q

Name (4) factors that can influence gas flow rates.

1) __________
2) __________
3) __________
4) __________

A

1) the type of shielding gas used
2) type of thickness of material
3) position of welding
4) joint design

23
Q

Explain the terms cast and helix.

A

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.

24
Q

The mode of metal weld transfer with basic type core wires is:

A) spray
B) short circuit
C) globular
D) pulsed spray

A

C) globular

25
Q

What are the primary functions of the flux in FCAW wires?

A

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

26
Q

Explain the following FCAW wire classification: E491T-9CH

E \_\_\_\_\_\_\_\_\_\_
49 \_\_\_\_\_\_\_\_\_\_
1 \_\_\_\_\_\_\_\_\_\_
T \_\_\_\_\_\_\_\_\_\_
9 \_\_\_\_\_\_\_\_\_\_
CH\_\_\_\_\_\_\_\_\_\_
A 
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
27
Q

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

A

B) general classification for electrodes mot covered under any other classification

28
Q

Name (2) FCAW wires that can be used without external gas shielding.

A 
EXXXT -3
EXXXT -4
EXXXT -6
EXXXT -10
EXXXT -11
EXXXT -13
EXXXT -14
29
Q

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

A

D) high deposition rates

30
Q

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

A

C) gun & cable assembly

31
Q

Name (3) causes of porosity with FCAW.

1) ___________
2) ___________
3) ___________

A

1) lack of shielding gas
2) improper gun inclination
3) air drafts

32
Q

Name (3) advantages and (3) disadvantages of FCAW

Advantages

1) __________
2) __________
3) __________

Disadvantages

1) __________
2) __________
3) __________

A

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

Flux Cored Arc Welding (FCAW) (1 decks)

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