120103a-bB Wire Feed Welding Equipment and Consumables Part B Flashcards

Wire Feed Welding Equipment and Consumables : Part B

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1
Q

Define and describe the GMAW process in detail.

A

Answer: GMAW is an arc welding process that uses an arc between a continuous filler metal electrode and the weld pool. The process uses shielding gas from an externally supplied source.

Explanation: Gas Metal Arc Welding (GMAW), also known as MIG welding, involves creating an electric arc between a continuous wire electrode and the workpiece, which melts the wire to form a weld. Shielding gas protects the weld pool from atmospheric contamination, ensuring a clean weld.

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2
Q

What type of welding power source is most often used for GMAW?

A

Answer: Constant voltage (CV).

Explanation: GMAW typically uses a constant voltage power source, which maintains a steady voltage level during welding. This helps in creating a stable arc and consistent welding conditions, essential for quality welds.

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3
Q

List three advantages and three disadvantages of GMAW.

A

Any three (3) of the following advantages are correct.
a) Lower skill requirements than SMAW
b) Excellent for light gauge metals
c) Good arc control when working with poor fit-ups
d) Less heat input means less distortion than SMAW
e) High production rates
f) No slag to remove, little or no post-weld clean-up

Any three (3) of the following disadvantages are correct.
a) Special equipment required resulting in the higher initial cost
b) Equipment requires more maintenance and down time
c) Lack of fusion can be a problem
d) Cannot be used outdoors or in drafty locations
e) High radiant energy requires protection for the welder and others in the
vicinity
f) Wire feeder must be in close proximity to the welding

Explanation: GMAW offers several benefits like high efficiency and ease of use, but it also has limitations such as higher costs and specific environmental requirements. Understanding these can help in choosing the right welding process for different applications.

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4
Q

Interpret the B-G 49A 3 C G2 electrode classification.

A

Answer and Explanation:

B-G 49A 3 C G2 is a classification that breaks down into several components:
B: Indicates the electrode was classified by tensile strength and with an average 27-joule impact test.
G: Designates using a gas shielded metal arc welding process.
49A: Refers to the minimum tensile strength of the deposited weld metal in the as-welded condition in megapascals (MPa) divided by 10.
3: Indicates a minimum temperature of -30°C for impact tests.
C: Designates CO2 as the shielding gas.
G2: Specifies a particular chemical analysis of the designated filler metal.

This classification system provides detailed information about the properties and suitable applications of the electrode, crucial for selecting the right filler metal for specific welding tasks. Understanding these classifications ensures that welders use materials that meet the necessary strength, impact resistance, and shielding requirements for their specific welding applications.

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5
Q

Describe the operating principles of FCAW.

A

Answer: FCAW uses an arc established between a continuously fed consumable electrode and the workpiece. Appropriate settings made by the operator maintain a constant burn-off rate of the wire electrode. The arc length is maintained automatically depending on the power source and wire drive system used. Shielding gas can be externally applied and/or obtained from a flux within the hollow electrode core.

Explanation: Flux Cored Arc Welding (FCAW) combines the simplicity of MIG welding with the added efficiency of a flux core. This allows for increased penetration and a higher welding speed than MIG welding. The flux in the core of the wire automatically provides the shielding gas, making FCAW particularly useful for outdoor welding where wind can disperse the shielding gas in conventional MIG welding.

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6
Q

What is the electrode extension range for self-shielded FCAW?

A

Answer: For self-shielded electrodes, extensions range from 19 mm to 95 mm (¾” to 3¾”).

Explanation: The electrode extension in FCAW, especially in self-shielded applications, is important for ensuring proper arc stability and weld penetration. Longer extensions are typically used in self-shielded FCAW to allow for better flux coverage and gas shielding produced from the flux core.

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7
Q

List three advantages and three disadvantages of FCAW.

A

Any three (3) of the following advantages are correct.
a) The deposition rate is up to four times greater than with SMAW.
b) There is a high operating factor, so it is easily mechanized.
c) The visible arc is easy to use.
d) The weld metal deposits are high quality.

Any three (3) of the following disadvantages are correct.
a) The equipment is more expensive to purchase than that needed for SMAW.
b) More smoke and fumes are generated, which require suitable exhaust
removal equipment.
c) The wire feeder must be in close proximity to the welding.
d) Equipment is more complex than SMAW, requiring more maintenance.

Explanation: FCAW offers a high deposition rate, making it efficient for industrial uses, and its automated nature leads to consistent weld quality. However, the cost of equipment and maintenance, along with environmental considerations like fume extraction, can be challenging.

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8
Q

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

A

Answer: The primary functions include providing deoxidizers and scavengers to remove impurities, forming a slag cover to protect the weld metal from atmospheric contamination, acting as an arc stabilizer for a stable arc with less spatter, adding alloying elements for desired mechanical and metallurgical properties, and generating shielding gas to displace atmospheric air.

Explanation: The flux in FCAW wires serves multiple critical roles, from protecting the weld pool to stabilizing the arc and even contributing to the metallurgical properties of the weld. Its multifunctionality makes FCAW versatile and effective in various welding applications.

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9
Q

Name two FCAW wires that can be used without external gas shielding.

A

Answer: Any of the following types are correct: EXXXT-3, -4, -6, -10, -11, -13, or -14.

Explanation: These specific types of FCAW wires are designed to produce their own shielding gas from the flux, making them suitable for outdoor applications or in environments where external gas shielding is impractical.

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10
Q

Explain the E491T-9CH FCAW electrode wire classification.

A

Answer: ‘E’ indicates electrode. ‘49’ indicates tensile strength measured in megapascals divided by 10. ‘1’ refers to all-position application. ‘T’ indicates tubular wire. ‘9’ indicates the slag system, current, polarity, and shielding gas. ‘CH’ refers to controlled hydrogen.

Explanation: This classification system provides detailed information about the electrode’s characteristics, including its mechanical strength, suitable positions for welding, type of wire (tubular), and the specific slag system and shielding gas requirements. Understanding these classifications is essential for selecting the appropriate wire for a given welding task.

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11
Q

Explain the E491C-6 MCAW electrode wire classification.

A

Answer: E indicates electrode. 49 refers to the minimum tensile strength of the deposited weld metal in the as-welded condition in megapascals (MPa) divided by 10. 1 refers to all-position application. C indicates metal-cored wire. 6 indicates the slag system, current, polarity, and shielding gas.

Explanation: The classification E491C-6 for MCAW electrode wire provides detailed information about the electrode’s characteristics:
E for electrode.
49 for the tensile strength of the weld metal.
1 for its suitability for all-position welding.
C signifies that it’s a metal-cored wire.
6 relates to the wire’s slag system, current requirements, polarity, and the type of shielding gas to be used.

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12
Q

List three (3) advantages and three (3) disadvantages of MCAW.

A

Any three (3) of the following advantages are correct.
a) The deposition rate is up to four times greater than with SMAW.
b) There is a high operating factor, so it is easily mechanized.
c) There is no slag or inter-pass cleaning.
d) The weld metal deposits are high quality.

Any three (3) of the following disadvantages are correct.
a) The equipment is more expensive to purchase than that needed for SMAW.
b) More smoke and fumes are generated, which require suitable exhaust
removal equipment.
c) The wire feeder must be in close proximity to the welding.
d) Equipment is more complex than SMAW, requiring more maintenance.

Explanation: Metal Cored Arc Welding (MCAW) is known for its high efficiency and quality of welds, but it comes with higher equipment costs and maintenance needs. The wire feeder’s proximity can also be a limitation in certain welding setups.

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13
Q

What is the recommended mix of shielding gases for the C-3 and C-6 electrode classifications used for MCAW?

A

Answer: The recommended mix for both classifications is 85% Argon and 15% CO2.

Explanation: This particular mix of Argon and CO2 is commonly used in MCAW for the C-3 and C-6 classifications. It provides a good balance between weld quality, arc stability, and cost-effectiveness.

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14
Q

What need is increased when using shielding gases for wire feed processes?

a) The need for good lighting.
b) The need for good ventilation.
c) The need for heat shielding.
d) The need for eye protection.

A

b) The need for good ventilation. (Correct Answer)

Explanation: Good ventilation is essential when using shielding gases to prevent the build-up of harmful fumes and gases in the welding area, ensuring a safe working environment.

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15
Q

High ultraviolet radiation emissions from an open arc can cause atmospheric oxygen in the vicinity of the arc to convert to which of the following?

a) Ozone.
b) Carbon monoxide.
c) Carbon dioxide.
d) Argon.

A

a) Ozone. (Correct Answer)

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16
Q

What is a potential source of poisonous chemical fumes when welding?

a) Inert shielding gases.
b) Chlorinated degreasing solvents.
c) Carbon dioxide extinguishers.
d) Anti-spatter nozzle sprays.

A

b) Chlorinated degreasing solvents. (Correct Answer)

Explanation: Chlorinated degreasing solvents can release poisonous chemical fumes when exposed to the high temperatures of welding, posing health hazards.

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17
Q

What is the gas metal arc welding process also known as?

a) MIG welding.
b) Flux cored arc welding.
c) Self-shielding process.
d) Shielded metal arc welding.

A

a) MIG welding. (Correct Answer)

Explanation: Gas Metal Arc Welding (GMAW) is commonly known as MIG (Metal Inert Gas) welding, a term that originated from its use of inert gases like argon and helium.

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18
Q

GMAW is recommended for use on which of the following metals?

a) Stainless steel.
b) Aluminum.
c) Copper alloys.
d) Carbon and low alloy steels.
e) All the above.

A

e) All the above. (Correct Answer)

Explanation: GMAW is versatile and effective for a wide range of metals, including stainless steel, aluminum, copper alloys, and carbon and low alloy steels.

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19
Q

What is the gas generated from that is used for self-shielded FCAW?

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. (Correct Answer)

Explanation: In self-shielded Flux-Cored Arc Welding (FCAW), the flux within the wire generates the shielding gas necessary for the welding process.

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20
Q

The MCAW process uses the same equipment as which process?

a) SMAW.
b) GTAW.
c) FCAW.
d) OAW.

A

c) FCAW. (Correct Answer)

Explanation: Metal-Cored Arc Welding (MCAW) uses similar equipment to Flux-Cored Arc Welding (FCAW), including wire feeders, power sources, and gun and cable assemblies.

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21
Q

How are wire feed guns rated?

a) By voltage-carrying capacity.
b) By physical size.
c) By current-carrying capacity.
d) By shielding gas flow rate.

A

c) By current-carrying capacity. (Correct Answer)

Explanation: Wire feed guns are rated by their current-carrying capacity, which determines the maximum electrical current the gun can handle effectively and safely.

22
Q

What is the major factor required when choosing between an air-cooled or a water-cooled gun?

a) Shielding gas.
b) Current and voltage.
c) Joint design.
d) Base metal alloy.

A

b) Current and voltage. (Correct Answer)

Explanation: The choice between an air-cooled or water-cooled gun largely depends on the current and voltage requirements of the welding process. Higher current applications typically require water-cooled guns to manage the increased heat.

23
Q

What does a constant voltage (CV) machine produce?

a) Drooping volt-amp curve.
b) Rising volt-amp curve.
c) Relatively flat volt-amp curve.
d) Constantly changing volt-amp curve.

A

c) Relatively flat volt-amp curve. (Correct Answer)

Explanation: Constant voltage (CV) machines produce a relatively flat volt-amp curve, which is essential for maintaining a consistent arc length and welding output.

24
Q

Which power source is best suited for the short-circuit mode of metal transfer?

a) Rising arc voltage.
b) Constant voltage. (Correct Answer)
c) Constant current.
d) Constant amperage.

A

b) Constant voltage. (Correct Answer)

Explanation: The short-circuit mode of metal transfer works best with a constant voltage power source, as it maintains a consistent voltage level essential for a stable short-circuit transfer.

25
Q

What type of volt-amp curve does a constant voltage machine produce?

a) Flat.
b) Variable.
c) Rising.
d) Drooping.

A

d) Drooping. (Correct Answer)

Explanation: A constant voltage machine produces a drooping volt-amp curve, which helps in stabilizing the arc during welding, especially in processes like GMAW and FCAW.

26
Q

Which type of welding machine produces an almost horizontal output slope?

a) Constant current machine.
b) Constant voltage machine.
c) Rising arc voltage machine.
d) High amperage potential welding machine.

A

b) Constant voltage machine. (Correct Answer)

Explanation: Constant voltage machines produce an almost horizontal output slope, which is crucial for processes like GMAW, where arc length consistency is vital.

27
Q

What is one of the main advantages of metal core wires?

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. (Correct Answer)

Explanation: One of the main advantages of metal core wires is their high deposition rates. This makes them highly efficient for welding applications that require high productivity.

28
Q

What does the powder in a MCAW wire consist mostly of?

a) Flux.
b) Metal.
c) Slag formers.
d) Arc stabilizers.

A

b) Metal.

Explanation: The powder in Metal-Cored Arc Welding (MCAW) wire is primarily made up of metal, providing the core with properties that enhance the welding process, such as improved electrical conductivity and stability.

29
Q

When is the base metal’s composition the major factor to consider?

a) When selecting a shielding gas.
b) When selecting filler materials.
c) When selecting a power source.
d) When selecting current settings.

A

b) When selecting filler materials. (Correct Answer)

Explanation: The composition of the base metal is a major factor when selecting filler materials to ensure compatibility and the desired weld properties.

30
Q

Which organizations have written specifications for wire feed filler metals?

a) WCB and CSA.
b) CWB and AWS.
c) ASME and CWB.
d) AWS and CSA.

A

d) AWS and CSA (Correct Answer)

Explanation: The CSA and the American Welding Society (AWS) have established specifications for wire feed filler metals, setting standards for quality and performance.

31
Q

What is silicon, aluminum, and manganese used for when added to ER70S-2?

a) Stabilizers.
b) Deoxidizers.
c) Lubricators.
d) Indicators.

A

b) Deoxidizers. (Correct Answer)

Explanation: Silicon, aluminum, and manganese are added to ER70S-2 as deoxidizers. They help remove oxygen from the weld pool, improving weld quality and reducing the risk of porosity.

32
Q

What does cast refer to?

a) Circle formed by one wrap of the wire.
b) Method of forming the wire.
c) Natural twisting action of the wire during forming.
d) Ability of the wire to be pushed through a plastic liner.

A

a) Circle formed by one wrap of the wire. (Correct Answer)

Explanation: Cast refers to the circle formed by one wrap of the wire. It influences how the wire feeds and its ability to be unwound smoothly during welding.

33
Q

Describe the helix of a wire and the effect that it may have on welding.

A

Explanation: Helix refers to the natural twisting action of the wire during forming. Excessive helix can cause the wire to exit the contact tip erratically, leading to an unstable arc and potential issues in weld quality.

34
Q

What are wires packaged in sealed containers mainly protected from?

a) Smoke and fumes.
b) Moisture contamination.
c) Transportation damage.
d) Ultraviolet light radiation.

A

b) Moisture contamination. (Correct Answer)

Explanation: Sealed containers protect wires from moisture contamination, which can lead to issues like rust and poor welding performance.

35
Q

What is often the result of welds produced with improperly cleaned wires?

a) Wagon tracks.
b) Cold lapping.
c) Slag inclusions.
d) Porosity.

A

d) Porosity. (Correct Answer)

Explanation: Welds made with improperly cleaned wires often result in porosity, a defect where gases are trapped in the weld, compromising its integrity.

36
Q

What are filler metals containing additional deoxidizers intended for use on?

a) Moderately rusty low-carbon steels.
b) Alloy steels containing chromium.
c) Non-ferrous metals.
d) Stainless steels with more than 18% chromium.

A

a) Moderately rusty low-carbon steels. (Correct Answer)

Explanation: Filler metals with additional deoxidizers are intended for use on moderately rusty low-carbon steels. The deoxidizers help counteract the effects of rust and impurities.

37
Q

What does the ‘G’ stand for in the CSA FCAW electrode classification E492T-G?

a) Gas shielded.
b) General classification for electrodes not 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 not covered under any other classification. (Correct Answer)

Explanation: In the CSA FCAW electrode classification E492T-G, ‘G’ stands for a general classification for electrodes not covered under any other specific classification.

38
Q

In the GMAW short-circuiting transfer mode, metal is transferred during which situation?

a) When the electrode comes in contact with the weld pool.
b) As large globules are released from the filler wire.
c) As fine droplets moving axially across the open arc.
d) When a high current arc pulse ejects metal from the filler wire.

A

a) When the electrode comes in contact with the weld pool. (Correct Answer)

Explanation: In the GMAW short-circuiting transfer mode, metal is transferred when the electrode comes in contact with the weld pool. This causes a short circuit, momentarily extinguishing the arc and allowing the transfer of metal.

39
Q

Very fine droplets of metal axially transferred across the arc describe what mode of metal transfer?

a) Short-circuiting
b) Globular
c) Spray
d) Pulsed spray

A

c) Spray (Correct Answer)

Explanation: The spray transfer mode is characterized by very fine droplets of metal being transferred across the arc in a steady stream. This mode is typically used for thicker materials and flat or horizontal positions.

40
Q

Which GMAW mode of metal transfer is best suited for welding thin metals?

a) Short-circuiting arc transfer
b) Globular spray arc transfer
c) Spray arc transfer
d) Pulsed arc transfer

A

a) Short-circuiting arc transfer (Correct Answer)

Explanation: Short-circuiting arc transfer is best suited for welding thin metals due to its lower heat input, which reduces the risk of warping or burn-through.

41
Q

Which MCAW mode of metal transfer is best suited for welding thin metals?

a) Short-arc transfer
b) Globular spray arc transfer
c) Spray arc transfer
d) Pulsed arc transfer

A

d) Pulsed arc transfer (Correct Answer)

Explanation: Pulsed arc transfer in Metal-Cored Arc Welding (MCAW) is suitable for welding thin metals as it provides controlled heat input and minimizes distortion.

42
Q

Where are the drive rolls located on a pull-type drive system?

A

Answer: On the gun unit.

Explanation: In a pull-type drive system, the drive rolls are located on the gun unit itself, which pulls the wire through the liner, reducing friction and allowing for smoother wire feeding.

43
Q

What is a pull type welding gun designed to be used with?

a) Hard wires
b) Soft wires
c) Solid core wires
d) Tubular wires

A

b) Soft wires (Correct Answer)

Explanation: Pull type welding guns are designed for use with soft wires, such as aluminum, where the wire’s softness requires gentle handling to prevent deformation.

44
Q

What type of wire drive system allows greater machine-to-work distances?

a) Push system
b) Push-pull system
c) Two drive roll system
d) Four drive roll system

A

b) Push-pull system (Correct Answer)

Explanation: The push-pull system allows for greater distances between the machine and the work due to the combination of pushing and pulling mechanisms, which enhances wire feeding reliability over longer distances.

45
Q

What is the most popular type of wire feed system when using GMAW on mild steel?

a) Pull system
b) Push system
c) Push-pull system
d) Spool-on-gun system

A

b) Push system (Correct Answer)

Explanation: The push system is most popular for GMAW on mild steel due to its simplicity and effectiveness in feeding the wire smoothly from the machine to the gun.

46
Q

What is the gun shown in Figure 16 primarily used for?

A

Answer: Welding aluminum.

Explanation: The specific design and features of the gun shown in Figure 16 make it ideal for welding aluminum, a metal that requires particular handling due to its properties.

47
Q

In addition to maximizing operator comfort, what is the purpose of the curved neck on a welding gun?

a) It allows the use of a wider range of wire sizes.
b) It helps prevent a burn-back of the electrode to the contact tip.
c) It ensures proper electrical transfer to the wire electrodes.
d) It allows for better access to tight spaces.

A

c) It ensures proper electrical transfer to the wire electrodes. (Correct Answer)

Explanation: The curved neck of a welding gun ensures proper electrical transfer to the wire electrodes, which is crucial for a stable and effective welding process.

48
Q

What is the welding cable assembly constructed to do?

a) Supply current from the machine to the electrode holder.
b) Supply current, gas, and wire to the welding gun.
c) Complete an electrical circuit between the machine and the work.
d) Supply current from the wall receptacle to the welding machine.

A

b) Supply current, gas, and wire to the welding gun.

49
Q

What types of conduit liner are most often used with soft wires?

A

Teflon, nylon or plastic liners.

Explanation: Teflon or nylon liners are most commonly used with soft wires like aluminum. These materials allow the wire to feed smoothly through the gun without causing damage or deformation to the wire.

50
Q

What is generally the longest practical feed cable with small diameter wire and a push feed system?

A

Answer: 4.5 m (15 ft). (Correct Answer)

Explanation: The longest practical distance for effective wire feeding with small diameter wire in a push feed system is generally 4.5 meters (15 feet). Beyond this distance, the wire may encounter feeding problems due to resistance in the liner.

51
Q

What is the main purpose of the contact tube?

a) It transfers the welding current to the filler wire.
b) It prevents pre-ignition of the arc in the nozzle.
c) It directs shielding gas to the weld zone.
d) It acts as an insulator between the wire and the gun.

A

a) It transfers the welding current to the filler wire. (Correct Answer)

Explanation: The main purpose of the contact tube (or contact tip) is to transfer the welding current to the filler wire. This component is essential for establishing the arc and ensuring consistent welding.

52
Q

What is the purpose of a gas nozzle?

A

Answer: The gas nozzle directs shielding gas to the weld zone. (Correct Answer)

Explanation: The gas nozzle’s primary function is to direct the flow of shielding gas over the weld pool. The shielding gas protects the weld area from atmospheric contamination, crucial for achieving high-quality welds.