Mod # 5 - GMAW - Multiple Choice
The gas metal arc welding process is also known as: a) MIG welding. b) flux cored arc welding. c) self-shielding process. d) shielded metal arc welding
a) MIG welding.
What should you do when the liner becomes kinked? a) Replace it. b) Squeeze it in a vice until it straightens out, and place back into service. c) Cut the kinked portion out, rejoin using manufacturer-approved fittings, and place back into service. d) Stretch the liner until it straightens out, and place back into service.
a) Replace it.
What may occur when too much slope is set on a CP machine? a) bending and stubbing of the wire b) decreased electrical stickout c) increased arc length d) increased weld puddle fluidity
a) bending and stubbing of the wire
Changing the gun (electrode holder) inclination will: a) change the penetration of the weld. b) have no effect on the weld. c) cause the wire to pile up at the drive rolls. d) cause the wire to feed unevenly.
a) change the penetration of the weld.
With GMAW wire, cast refers to the: 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) circle formed by one wrap of the wire.
Which gas is the lightest? a) hydrogen b) argon c) helium d) oxygen
a) hydrogen.
The purpose of a flowmeter is to: a) maintain a constant flow of gas. b) maintain a constant pressure of gas. c) maintain a post flow of gas. d) reduce source pressure to working pressure.
a) maintain a constant flow of gas.
Filler metals containing additional deoxidizers are 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) moderately rusty low carbon steels
High ultraviolet radiation emissions from GMAW can cause atmospheric oxygen in the vicinity of the arc to convert to: a) ozone. b) carbon monoxide. c) carbon dioxide. d) argon.
a) ozone.
Moisture and dirt on the surface of the wire electrode is likely to cause: a) porosity. b) cold lap. c) electrical shock. d) post-weld stress cracking.
a) porosity.
Compared to CO2, argon is an excellent shielding gas for GMAW because it allows the use of: a) spray metal transfer. b) globular metal transfer. c) short-circuit metal transfer. d) low gas flow rates in globular transfer.
a) spray metal transfer
What is the main purpose of the contact tube? a) transfers the welding current to the filler wire b) prevents pre-ignition of the arc in the nozzle c) directs shielding gas to the weld zone d) to act as an insulator between the wire and gun
a) transfers the welding current to the filler wire
GMAW may be used in the semi-automatic or automatic operation modes. a) true b) false
a) true
To obtain an accurate reading from a flowmeter, it must be mounted in the: a) vertical position. b) overhead position. c) horizontal position. d) flat position.
a) vertical position.
Flowmeters are calibrated to indicate the: a) volume of shielding gas supplied. b) capacity of the shielding gas cylinder. c) pressure of shielding gas supplied. d) density of shielding gas supplied.
a) volume of shielding gas supplied.
What type of bead is usually used for the cover pass on a 3F weld on 10 mm (3/8") material? a) weave bead b) stringer bead c) modified lazy L bead d) long dwell crown bead
a) weave bead
In the GMAW short-circuiting transfer mode, metal is transferred: a) when the electrode comes in contact with the weld pool. b) as large globules 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) when the electrode comes in contact with the weld pool.
When using GMAW, an increase in the arc voltage produces a: a) wider arc stream and shallower penetration. b) wider arc stream and deeper penetration. c) narrower arc stream and shallower penetration. d) narrower arc stream and deeper penetration.
a) wider arc stream and shallower penetration
Slope and inductance are used to: a) increase the weld metal deposition rate. b) reduce penetration and heat input. c) lower average current levels for spray transfer. d) reduce spatter and improve arc stability.
d) reduce spatter and improve arc stability.
What controls amperage on a CV machine? a) voltage b) diameter of wire c) watts d) wire feed speed
d) wire feed speed
Stubbing is caused by excessive: a) inductance. b) voltage. c) resistance. d) wire feed speed.
d) wire feed speed.
The recommended stickout for short circuiting metal transfer is: a) 3.2 mm (1/8"). b) 10 mm (3/8"). c) 16 mm (5/8"). d) 22 mm (7/8").
b) 10 mm (3/8").
What joint configuration would you likely use for a 1G weld with Vee groove preparation on 10 mm (3/8") material? a) 4 mm (5/32") root face, 2.5 mm (3/32") gap b) 4 mm (5/32") gap, 1.6 mm (1/16") root face c) 4 mm (5/32") root face, 4 mm (5/32") gap d) 1.6 mm (1/16") gap, 3.2 mm (1/8") root face
b) 4 mm (5/32") gap, 1.6 mm (1/16") root face
What would likely be the normal electrode angle when doing single-pass 1F welds? a) 90° to the joint angle b) 45° to the joint angle c) 15° - 20° to the joint angle d) 180° relative to the welder's position
b) 45° to the joint angle
How should you lay the beads when surface welding for buildup work? a) Space them so that they are 3.2 mm (1/8") apart. b) Blend them together so they form a solid layer of weld metal. c) Space them so that they are 6.4 mm (1/4") apart. d) The toe of one bead should meet the toe of the next bead.
b) Blend them together so they form a solid layer of weld metal.
The power sources used for pulsed spray transfer are: a) CC silicone diode rectifiers with solid state control. b) DC synergic, microprocessor-controlled. c) DC generators with external slope and inductance controls. d) CV rectifiers with adjustable voltage and inductance controls.
b) DC synergic, microprocessor-controlled.
Which drive roll design is preferred for GMAW using solid wire? a) flat b) V-groove c) angled d) knurled
b) V-groove
When using GMAW on mild steel with carbon dioxide shielding, which type of filler wire should be selected? a) an oxidized wire b) a deoxidized wire c) a high alloy wire d) a flux coated wire
b) a deoxidized wire
Ideally, a welding power source should be located in: a) a confined area at floor level. b) an uncluttered, well ventilated area of the shop. c) the centre area of the shop. d) an unventilated, specially enclosed mezzanine area.
b) an uncluttered, well ventilated area of the shop
A potential source of poisonous chemical fume when welding is: a) inert shielding gases. b) chlorinated degreasing solvents. c) carbon dioxide extinguishers. d) anti-spatter nozzle sprays.
b) chlorinated degreasing solvents
A welding machine that produces an almost horizontal output slope is a: a) constant current machine. b) constant arc voltage machine. c) rising arc voltage machine. d) high amperage potential welding machine.
b) constant arc voltage machine.
The power source best suited for the short-circuit mode of metal transfer is a: a) rising arc voltage power source. b) constant voltage power source. c) constant current power source. d) constant amperage power source.
b) constant voltage power source.
The major factor in choosing between an air-cooled or a water-cooled gun is the required: a) shielding gas. b) current/voltage. c) joint design. d) base metal alloy.
b) current/voltage.
Silicon, aluminum and manganese, when added to ER49S-2 are used as: a) stabilizers. b) deoxidizers. c) lubricators. d) indicators.
b) deoxidizers.
What is the likely weld progression for the first pass on a 3F weld on 10 mm (3/8") material? a) uphill b) downhill c) slight of hand d) back step
b) downhill
Welding power sources designed only for GMAW can be used for shielded metal arc welding (SMAW). a) true b) false
b) false
The wire spool hub should be adjusted to: a) prevent the unwinding of the wire spool. b) feed freely, yet prevent a backlash of wire when feeding is stopped. c) allow the wire to be removed without restriction. d) run the wire from the bottom of the roll only.
b) feed freely, yet prevent a backlash of wire when feeding is stopped
The composition of the base metal is the major factor to consider when selecting: a) a shielding gas. b) filler materials. c) a power source. d) current settings.
b) filler metals.
When oxygen and nitrogen from the atmosphere become mixed in the molten weld metal, they: a) increase the tensile strength of the weld metal. b) form harmful oxides and nitrides in the weld metal. c) help increase the ductility of the weld zone. d) increase the fracture toughness of the weld metal.
b) form harmful oxides and nitrides in the weld metal.
What must be considered before using a mini-bulk system? a) cylinder rental costs b) frequency of use c) cannot be used with argon gas d) availability of an external evaporator unit
b) frequency of use
What does the G stand for in the CSA GMAW electrode classification ER49S-G? a) gas shielded. b) general classification for new electrodes not covered under any other classification. c) approved 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 new electrodes not covered under any other classification.
Which modes of metal transfer are possible with GMAW using 0.9 mm (0.035") mild steel wire and carbon dioxide shielding gas? a) spray and globular b) globular and short circuiting c) short circuiting and pulse spray d) spray and pulse spray
b) globular and short-circuiting
The use of shielding gases for GMAW increases the need for: a) good lighting. b) good ventilation. c) good heat shielding. d) better eye protection.
b) good ventilation.
A characteristic of carbon dioxide shielding gas used with short-circuiting metal transfer is: a) a deep, narrow penetration pattern. b) high weld metal loss in the form of spatter. c) excellent surface cleaning action. d) a shallow, wide penetration pattern.
b) high weld metal loss in the form of spatter
The addition of oxygen to argon causes the temperature of the molten metal to: a) decrease. b) increase. c) stabilize. d) oxidize.
b) increase
Argon and helium are: a) reactive gases. b) inert gases. c) ionized gases. d) non-conductive gases.
b) inert gases.
When wires are packaged in sealed containers, it is mainly to protect them from: a) smoke and fumes. b) moisture contamination. c) transportation damage. d) ultraviolet light radiation.
b) moisture contamination
Which GMAW mode of metal transfer is best suited for all-position welding? a) globular transfer b) pulsed spray arc transfer c) spray arc transfer d) submerged arc transfer
b) pulsed spray arc transfer
When using GMAW on mild steel, the most popular type of wire feed system is a: a) pull system. b) push system. c) push-pull system. d) spool-on-gun system.
b) push system.
What type of wire drive system allows greater machine-to-work distances? a) push system b) push-pull system c) 2 drive roll system d) 4 drive roll system
b) push-pull system
Excessive drag from a dirty liner is likely to cause: a) porosity and cracking in the weld. b) slippage or bird nesting at the drive rolls. c) excessive undercut or lack of fusion. d) damage to the liner and contact tip.
b) slippage or bird nesting at the drive rolls
What is the major cause of cold lap when using GMAW short-circuit metal transfer? a) fast travel with a small bead b) slow travel with a large bead c) slope control set to a flat volt-amp curve d) wire stickout too short
b) slow travel with a large bead
A pull type welding gun is designed to be used with: a) hard wires. b) soft wires. c) solid core wires. d) tubular wires.
b) soft wires.
The welding cable assembly used for GMAW is constructed to: 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.
b) supply current, gas and wire to the welding gun.
When a change is made to the slope adjustment: a) the open circuit voltage setting automatically changes. b) the available output amperage changes. c) the polarity needs to be changed also. d) wire size needs to be changed.
b) the available output amperage changes.
The main purpose of the slope control is: a) to increase control of input current surges. b) to limit the short circuiting current. c) to change the open circuit voltage. d) to change wire feed speed.
b) to limit the short circuiting current.
Spray transfer employs higher: a) inductance settings. b) voltage settings. c) reactance settings. d) amounts of CO2 shielding.
b) voltage settings.
What is the recommended gun angle for the first pass of a 2F weld on 10 mm (3/8") material with three stringer bead passes specified? a) 90° to the vertical plane b) 90° to the horizontal plane c) 45° to the vertical and horizontal planes d) 270° to the welder's initial position prior to arc ignition
c) 45° to the vertical and horizontal planes
What minimum percentage of argon is required is required in order to achieve spray transfer? a) 65% b) 76% c) 85% d) 98%
c) 85%
What should you check for when adjusting from short-circuiting to spray transfer with GMAW? a) Ensure wire feeder drive motor is well lubricated. b) Make sure the power source has a high frequency current control. c) Make sure the gun is rated to handle higher currents. d) Make sure the wire electrode is at least 0.9 mm (0.035") minimum diameter.
c) Make sure the gun is rated to handle higher currents.
What position(s) can short-circuit metal transfer be used in? a) flat position only b) flat and horizontal positions c) all positions d) vertical downhill position only
c) all positions
What is a major advantage of pulsed spray transfer? a) increased heat input when compared to spray transfer b) low deposition rates with increased spatter c) all-position welding on thinner materials d) increased amounts of distortion
c) all-position welding on thinner materials
How are GMAW guns rated? a) by voltage-carrying capacity b) by physical size c) by current-carrying capacity d) by shielding gas flow rate capacity
c) by current-carrying capacity
What is the most common material used in the construction of gas nozzles? a) high temperature ceramics b) stainless steel c) copper alloys d) low alloy steel
c) copper alloys
Stickout is the distance between the: a) contact tube and the nozzle. b) nozzle and the end of the wire electrode. c) end of the contact tip and the end of the wire electrode. d) nozzle and the metal being welded.
c) end of the contact tip and the end of the wire electrode.
How often should you clean the conduit liner of a wire drive set-up? a) once per day b) after 20 hours of operation c) every time the wire spool is changed d) the liner should never need cleaning
c) every time the wire spool is changed
When 1% to 5% oxygen is added to argon shielding gas, it is to: a) reduce spatter. b) increase the deposition rate. c) improve wetting action. d) reduce welding costs.
c) improve wetting action.
To increase arc length when welding with GMAW, you would: a) use a longer contact tip. b) increase wire feed speed. c) increase arc voltage. d) use a shorter contact tip.
c) increase arc voltage.
The preferred method of measuring shielding gas supply is: a) kilograms per square centimetre (pounds per square inch). b) kilograms per minute (pounds per hour). c) litres per minute (cubic feet per hour). d) surface metres per minute (surface feet per hour).
c) litres per minute (cubic feet per hour).
Power sources developed for pulsed spray transfer will: a) reduce arc force and therefore increase penetration on thicker materials. b) reduce average current levels required for short-circuiting metal transfer. c) permit spray transfer at average current levels below the transition current values. d) eliminate spatter and burnback in the globular transfer mode.
c) permit spray transfer at average current levels below the transition current values.
When using the short circuiting mode of metal transfer, inductance controls the: a) arc length by limiting the voltage. b) maximum available amperage. c) rate of rise and fall of amperage. d) burn-off rate of the electrode.
c) rate of rise and fall of amperage.
Constant arc voltage (CAV) machines produce a: a) drooping volt-amp curve. b) rising volt-amp curve. c) relatively flat volt-amp curve. d) constantly changing volt-amp curve.
c) relatively flat volt-amp curve.
Push-pull guns are an advantage when: a) soft wires are taken through short liners. b) hard wires are taken through short liners. c) soft wires are taken through long liners. d) hard wires are taken through long liners.
c) soft wires are taken through long liners
Very fine droplets of metal transferred across the arc in an axial fashion, describes what mode of metal transfer? a) short-circuiting b) globular c) spray d) pulsed spray
c) spray
In addition to maximizing operator comfort, what is the purpose of the curved neck on a GMAW welding gun? a) allows the use of a wider range of wire sizes b) to help prevent a burn-back of the electrode to the contact tip c) to ensure proper electrical transfer to the wire electrode d) to allow use of all wire electrode types
c) to ensure proper electrical transfer to the wire electrode
How will penetration be affected when stickout is increased? a) will increase penetration b) penetration will not be affected c) will decrease penetration d) will affect penetration on groove welds only
c) will decrease penetration
Improperly stored wires most often produce welds with: a) wagon tracks. b) cold lapping. c) slag inclusions. d) porosity.
d) porosity.
Which organizations have written specifications for GMAW filler metals? a) WCB and CSA b) CWB and AWS c) ASME and CWB d) AWS and CSA
d) AWS and CSA.
What can result from a poor work lead connection? a) Overheating of the power source main transformer coil. b) Erratic wire feed speeds. c) Excessive penetration. d) An unstable arc.
d) An unstable arc.
In what positions can you do surface welding with GMAW using short-circuit metal transfer? a) flat position only b) flat and horizontal positions only c) all positions except vertical d) all positions
d) all positions
Which of the following gas mixes tends to produce low-crowned weld beads on stainless steels? a) helium-carbon dioxide b) argon-carbon dioxide c) nitrogen-carbon dioxide d) argon-helium-carbon dioxide
d) argon-helium-carbon dioxide
When arc hunting occurs, the problem is likely in the: a) wire feeder drive motor or the motor gearbox. b) wire speed control or the voltage control. c) drive rolls or the remote control switch. d) contact tip or the conduit liner.
d) contact tip or the conduit liner.
What type of volt-amp curve does a constant current machine produce? a) flat b) variable c) rising d) drooping
d) drooping
How is the work positioned for a 1F Tee joint? a) 90° and 0° to the horizontal plane b) 180° and 360° to the horizontal plane c) 120° and 60° to the horizontal plane d) each member at 45° to the horizontal plane
d) each member at 45° to the horizontal plane
What part of the GMAW system requires the most ongoing maintenance? a) power source b) regulator/flowmeter c) wire feeder d) gun and cable assembly
d) gun and cable assembly
What can be done to avoid regulator freeze-up when using CO2 gas? a) lower the gas flow rate b) increase the working pressure of the regulator c) cover the regulator body with insulating material d) install a line heater or manifold system
d) install a line heater or manifold system
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 of the above
e) all of the above
