Deck 10: Gas Metal Arc Welding Equipment, Setup, and Operation

Question 1

​What changes to the welding machine are required to change between short-circuiting and axial spray or between axial spray and buried arc transfer methods?

A) ​Change the shielding gas from Ar to 100% CO2 or He to Ar+O2.
B) ​Make the changes in the welding machine's voltage and amperage settings.
C) ​Increase the voltage.
D) ​Increase the amperage.

Answer 1

B

Question 2

Which of the following is true of axial spray transfers using high current settings?

A) Higher currents are needed with smaller diameter wires.
B) High current aids welding sheet metal because the high heat cuts through sheet metal.
C) High current settings may cause the weld to be difficult to control in out-of-position welds.
D) The need for higher current removes some restrictions on the process.

Answer 2

C

Question 3

As much as ____ can be added to the argon to increase the power in the arc without affecting the desirable qualities of the spray mode.

A) 10% oxygen
B) 20% nitrogen
C) 50% carbon dioxide
D) 80% helium

Answer 3

D

Question 4

In the pulsed-arc metal transfer current cycle, ____ refers to the surging electrical current passing through the transformer like a wave on water.

A) overshoot
B) ramp up
C) high pulse current
D) pulse width

Question 5

Which of the following is true of pull-type feed systems?

A) Feed motors are located at both ends of the electrode conduit.
B) The gun is heavier and more difficult to use.
C) Rethreading the wire takes little time.
D) The feed system uses a synchronized system.

Question 6

​Which metal transfer method occurs as the result of direct contact of the electrode to the molten weld pool?

A) ​Short-circuiting transfer
B) ​Axial spray transfer
C) ​Globular transfer
D) ​Buried-arc transfer

Question 7

Which of the following is true of GMA spot welding?

A) Welds can only be made in thin materials.
B) The weld cannot be made if only one side of the materials to be welded is accessible.
C) The weld cannot be made when there is paint on the interfacing surfaces.
D) The burning back of the thin material allows the thicker metal to be melted.

Question 8

​The introduction of electronics into welding machines has given welders ______________.

A) ​more control over welding parameters
B) ​the ability to make any weld in any material
C) ​the ability to communicate with other welders over the web
D) ​the ability to make welds without shielding gas

Question 9

The shielding gas used on carbon steel is ____.

A) helium
B) carbon dioxide, or a mixture of carbon dioxide and argon
C) argon
D) argon, or a mixture of argon and helium

Question 10

In the ____ feed system, the electrode must have enough strength to be pushed through the conduit without kinking.

A) push-type
B) pull-type
C) push-pull-type
D) linear

Question 11

Which of the following is true of axial spray metal transfer?

A) It is rarely used by itself.
B) It transfers metal across the arc in larger droplets.
C) It involves a pulsing current.
D) There are hundreds of drops per second crossing from the wire to the base metal.

Question 12

Which of the following is true of perpendicular welding technique?

A) It has a good balance between penetration and reinforcement and is used on automated welding.
B) It has good bead visibility and makes welds with deeper joint penetration.
C) It has good joint visibility and makes welds with less joint penetration.
D) It works well on vertical up and overhead welds.

Question 13

The purpose of the ____ is to provide a steady and reliable supply of wire to the weld.

A) power source
B) electrode feed unit
C) electrode conduit
D) welding gun

Question 14

In the pulsed-arc metal transfer current cycle, ____ is a function of the time it takes the magnetic field in the transformer to collapse once the coil is de-energized.

A) step-off current
B) high current time
C) ramp up
D) ramp down

Question 15

In the pulsed-arc metal transfer current cycle, ____ is the peak current that flows across the arc during the high current pulse.

A) ramp up
B) high pulse current
C) high current time
D) step-off current

Question 16

Which of the following is true of backhand welding?

A) It has good joint visibility and makes welds with less joint penetration.
B) It works well on vertical up and overhead welds.
C) It has good bead visibility and makes welds with deeper joint penetration.
D) It has a good balance between penetration and reinforcement and is used on automated welding.

Question 17

GMA welding machines have ____ duty cycle.

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

Question 18

____ is a series of ridges cut into the groove.

A) Ridging
B) Smoothing
C) Knurling
D) V-grooving

Question 19

MAG is short for ____.

A) metal arc gas welding
B) metal active gas welding
C) metal action gas welding
D) metal anion gas welding

Question 20

In axial spray metal transfer, the shielding gas is usually a mixture of ____.

A) 95% to 98% argon and 2% to 5% oxygen
B) 2% to 5% argon and 95% to 98% oxygen
C) 50% argon and 50% oxygen
D) 5% argon and 95% oxygen

Question 21

​The ________ current of the spray mode produces good penetration and fusion, and the ____ current allows the weld pool to cool and contract slightly.

A) ​DCEN, DCEP
B) ​DCEP, DCEN
C) ​AC DCEP
D) ​high, low

Question 22

The ____________________ rate is the measure of the weld metal deposited.

Question 23

​The rate at which the current builds up the magnetic field and the resulting welding current is called ________.

A) ​slope
B) ​reactance time
C) ​magnetic decay and response time
D) ​response cycles

Question 24

​The GMAW-S process does not produce enough heat to make quality welds in sections much thicker than 1/4 in.(6 mm) unless it is used for the root pass on a grooved weld or to fill gaps in joints.

A) ​1/2 in.(13 mm)
B) ​5/16in.(8 mm)
C) ​1/4 in.(6 mm)
D) ​1/8 in.(3 mm)

Question 25

​Modulated current metal transfer can _______________________.

A) ​reduce spatter and fumes associated with conventional GMA welding
B) ​use 100% CO2 for all of the weld it makes
C) ​only use argon and helium as shielding gasses due to the higher deposition rates
D) ​be used for axial spray or short-circuiting metal transfer methods

Question 26

The ____________________ rate, measured in inches per minute or pounds per hour, is the rate at which the arc consumes the wire.

Question 27

____________________ systems interlock the power supply and wire feeder.

Question 28

​GMAW power supplies are ____ type machines.

A) ​constant-current and constant-voltage
B) ​constant-voltage and constant-potential
C) ​drooping arc voltage and constant-current
D) ​constant-current and constant-potential

Question 29

​In the pulsed-arc metal transfer current cycle, ____ refers to how the electric current in a transformer takes a few milliseconds to build up the magnetic field to full strength once the coil is energized.

A) ​pulse width
B) ​ramp down
C) ​ramp up
D) ​overshoot

Question 30

____________________ transfer can be used on thin materials and at a very low current range.

Question 31

​The modulated current transfer process can be used to make code quality root welds ______.

A) ​only if the root face is 1/8 in (3 mm) and the root opening is 7/32 in.(2.7 mm)
B) ​​when the root face is twice the size of the root opening but less than 5/32 in (4 mm)
C) ​even if the root opening and root face may vary as much as the code might allow
D) ​only in ferrous (steel) alloys

Question 32

​Changes in the step-off current have been associated with arc stability________________.

A) ​to make vertical up and overhead welds
B) ​when only AC power is available for the welding current
C) ​on aluminum and copper alloys
D) ​for some higher electrically resistant filler metals such as stainless steel and nickel alloys

Question 33

​When is axial spray metal transfer not practical?

A) ​When welding vertical up.
B) ​For pipe welding in any position.
C) ​For making welds on stainless steel.
D) ​For welding on sheet metal or thin sections.

Question 34

GMAW is almost free from spatter because it uses a mode of metal transfer called ____________________ metal transfer.

Question 35

​Why would a welder need extra burn protection for their eyes when making an axial spray weld?

A) ​To protect the eye from the increased weld spatter.
B) ​To protect the eye from the increased heat produced by axial spray arc welding.
C) ​The high welding current produces a great deal of UV light.
D) ​The hot metal can cause infrared light burns to the eye and face.

Question 36

​GMAW-P welds made on most metals other than steel use __________shielding gas.

A) ​2% oxygen + 98% argon
B) ​100% argon
C) ​25% helium + 75% argon
D) ​25%CO2 + 75% argon

Question 37

​An advantage of the ____ feed system is that the bulky system of gears is eliminated.

A) ​linear
B) ​pull-type
C) ​push-type
D) ​push-pull-type

Question 38

​When the GMAW-S process is properly tuned, what is the approximate rate of its cycling?

A) ​overshoot
B) ​ramp up
C) ​high pulse current
D) ​20 to 200 times per second

Question 39

​Which of the following is true of globular transfer?

A) ​It is used more commonly in combination with pulsed-spray transfer.
B) ​The arc's real work occurs when the current pulses above the transition current.
C) ​There are hundreds of drops per second crossing from the wire to the base metal.
D) ​The process requires a current level above the transition current.

Question 40

​What gas is added to argon for the axial spray transfer method transfer?

A) ​O2 (Oxygen)
B) ​CO2 (Carbon dioxide)
C) ​He (Helium)
D) ​N (Nitrogen)

Question 41

Explain why the power supply is critical in the short-circuiting transfer process.

Question 42

Explain how to measure the wire-feed ipm.

Question 43

Explain why the use of GMA welding can help reduce waste of filler metals.

Question 44

​Explain the modulated current metal transfer process.

Question 45

The ____________________ is the distance from the contact tube to the arc measured along the wire.

Question 46

The relationships between current and voltage with different combinations of arc length or wire-feed speeds are called ____________________ characteristics.

Question 47

​Modulated current metal transfer uses an extremely modified version of _________.

Question 48

The rate of voltage decrease as the amperage increases within the working range is known as ____________________.

Question 49

Explain the axial spray metal transfer process.

Question 50

​In modulated current metal transfer the wire feed speed is _____________.