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

Flashcards in GMAW, FCAW & SAW Deck (33)
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0

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).

1

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

2

What is the electrode extension range for self shielded FCAW?

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

3

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

4

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

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

A) CV

5

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

6

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

7

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

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

B) 60%

8

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

9

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

10

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

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

C) knurled

11

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

12

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

13

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

14

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.

15

What type of liner is recommended for FCAW wires?

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

D) steel

16

What controls arc length with FCAW?

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

B) voltage

17

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.

18

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

19

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

20

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")

21

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

22

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

23

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.

24

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

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

C) globular

25

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

26

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

27

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

28

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



29

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