Gas Metal Arc Welding

Instructions:

• Answer 50 questions in 15 minutes.
• If you are not ready to take this test, you can study here.
• Match each statement with the correct term.
• Don't refresh. All questions and answers are randomly picked and ordered every time you load a test.

This is a study tool. The 3 wrong answers for each question are randomly chosen from answers to other questions. So, you might find at times the answers obvious, but you will see it re-enforces your understanding as you take the test each time.

1. When is the metal transferred with short circuit transfer?
Controls the rate of flow of a shielding gas to the gun nozzle
When the filler wire is in direct contract with the base metal
3
Wire feed speed


2. What does inductance control?
To prevent drawing of liquid CO2 (Carbon Dioxide)
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
The time rate of response for the current rise and fall
Dry ice can form within the flow control openings and cause blockage of shielding gas


3. How are GMAW guns rated?
Motor driven generators - Transformer rectifiers - and Inverter designs
By there current carrying capacity
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
...


4. What is a typical flow rate of CO2 for short circuit transfer?
5.8 to 12.5 L/min
The Arc voltage
Reducing the gas source pressure to a constant working pressure
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground


5. With straight polarity where is 2/3 of the arc energy?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
The negative side of a welding unit
National Electrical Manufactures Association
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground


6. What wire are knurled drive rolls most commonly used on?
Constant- speed wire feeders and Voltage- sennsing wire feeders
Flux cored wires
V groove or U groove
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground


7. A pull type drive system is usually used on what type of material?
Constant current (CC)
Push type: Wire is fed by a set of drive rolls located in the wire feed unit - Pull type: Drive rolls mounted in the gun itself - Push- pull type: Combination of the two
Aluminum wire
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground


8. What does voltage do in an electrical circuit?
1/4 inch to 1/2 inch
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Voltage is the force that overcomes resistance to allow amperage flow
20 to 200 times per second


9. What is the effect of too much slope?
...
Insufficient current to melt the wire off cleanly
When the filler wire is in direct contract with the base metal
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10. Why is a fiber washer required and what cylinder gas requires it?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
To prevent leakage - Carbon Dioxide (CO2)
National Electrical Manufactures Association
Duty cycle


11. Give a brief description of the GMAW process
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
The Arc voltage
Welding process that joins metals by heating them with an electric arc
Spatter problems and poor weld appearance


12. What is the required arc voltage used for short circuit transfer?
Wire feed speed - Voltage control
To prevent leakage - Carbon Dioxide (CO2)
12 to 22 arc volts
Gas metal arc welding


13. What is the maximum distance that hard wire can be successfully pushed?
15 feet (4.5 meters)
Minimum distortion due to low heat input
Generally not as accurate
Aluminum wire


14. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
When the filler wire is in direct contract with the base metal
Push type: Wire is fed by a set of drive rolls located in the wire feed unit - Pull type: Drive rolls mounted in the gun itself - Push- pull type: Combination of the two
Wire feed speed - Voltage control
Gives arc voltage values to the control system of the feeder


15. What is a solenoid valve and what actuates it?
20 to 200 times per second
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
The Arc voltage
Guns


16. What 2 organizations designate specifications for GMAW wires?
Motor driven generators - Transformer rectifiers - and Inverter designs
When the filler wire is in direct contract with the base metal
AWS and CSA
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld


17. Why is a line heater required when using GMAW?
Constant current (CC)
Dry ice can form within the flow control openings and cause blockage of shielding gas
85%
To limit the short circuiting current so that spatter is reduced


18. What is an advantage of pulsed arc transfer with GMAW?
The resistace to electrical current flow increases with it. Causing the electrode to heat
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Constant voltage (CV)
Welding process that joins metals by heating them with an electric arc


19. What does the abbreviation NEMA stand for?
Higher 26 to 35 arc volts
National Electrical Manufactures Association
Controls the rate of flow of a shielding gas to the gun nozzle
Insufficient current to melt the wire off cleanly


20. What happens when the electrode extension is increased?
By there current carrying capacity
Wire feed speed
Duty cycle
The resistace to electrical current flow increases with it. Causing the electrode to heat


21. Why must CO2 cylinders be used in the vertical position?
To prevent drawing of liquid CO2 (Carbon Dioxide)
3
By there current carrying capacity
The Arc voltage


22. Draw a typical volt amp curve for a machine that is designed for GMAW
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Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Short- circuiting transfer - Globular transfer - Spray transfer
Higher 26 to 35 arc volts


23. In the GMAW process what does voltage control?
Minutes of elapsed time continually run (out of 10 minutes)
3
Puddle fluidity
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system


24. What is the purpose of the shielding gas used in GMAW?
By there current carrying capacity
Shielding the molten weld metal from atmospheric contamination
The resistace to electrical current flow increases with it. Causing the electrode to heat
Controls the rate of flow of a shielding gas to the gun nozzle


25. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Minutes of elapsed time continually run (out of 10 minutes)
Constant voltage (CV)
Shielding the molten weld metal from atmospheric contamination
Higher 26 to 35 arc volts


26. What controls the wire speed on a voltage sensing wire feeder?
The Arc voltage
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Aluminum wire
Push type: Wire is fed by a set of drive rolls located in the wire feed unit - Pull type: Drive rolls mounted in the gun itself - Push- pull type: Combination of the two


27. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Pressure - The rate of flow of a shielding gas
5.8 to 12.5 L/min
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Cause flaking - which can clog the liner and contact tube


28. What does the wire feeder control?
By there current carrying capacity
Speed of the feed motor and - starting / stopping electrode feed
The Arc voltage
SMAW - GTAW


29. What processes are constant current (CC) power sources designed to be used with?
1/4 inch to 1/2 inch
National Electrical Manufactures Association
Motor driven generators - Transformer rectifiers - and Inverter designs
SMAW - GTAW


30. What are the 2 types of wire feeders available?
Short- circuiting transfer - Globular transfer - Spray transfer
5.8 to 12.5 L/min
Constant- speed wire feeders and Voltage- sennsing wire feeders
When the filler wire is in direct contract with the base metal


31. What is the purpose of a regulator and what does it indicate on its gauges?
Reducing the gas source pressure to a constant working pressure
12 to 22 arc volts
...
Wire feeds smoothly (yet will slip should a problem occur in the gun)


32. What type of power source is used with a constant speed wire feeder?
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Constant voltage (CV)
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Voltage is the force that overcomes resistance to allow amperage flow


33. What is the recommended electrode stick- out for .035 solid wire?
Pressure vessels and the piping industry
1/4 inch to 1/2 inch
Pressure - The rate of flow of a shielding gas
DCEP (Direct Current Electrode Positive) Reverse Polarity


34. What is the main purpose of 'slope'?
To limit the short circuiting current so that spatter is reduced
Aluminum wire
(DCEP) Direct Current Electrode Positive or Reverse polarity
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld


35. What 2 controls are found on a GMAW set- up?
(DCEP) Direct Current Electrode Positive or Reverse polarity
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To limit the short circuiting current so that spatter is reduced
Wire feed speed - Voltage control


36. What current and polarity is generally used with GMAW?
DCEP (Direct Current Electrode Positive) Reverse Polarity
5.8 to 12.5 L/min
1/4 inch to 1/2 inch
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun


37. How many times per second does short circuiting take place?
Guns
Flux cored wires
3
20 to 200 times per second


38. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
3
AWS and CSA
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze


39. What controls amperage when using GMAW?
Wire feed speed
Insufficient current to melt the wire off cleanly
These terms are quite restrictive and often technically incorrect
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts


40. What does a flowmeter do and what does it measure?
...
Voltage is the force that overcomes resistance to allow amperage flow
Controls the rate of flow of a shielding gas to the gun nozzle
By there current carrying capacity


41. What would be an indication that the drive roll pressure is adjusted correctly?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
AWS and CSA
Pressure vessels and the piping industry
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun


42. In the GMAW process what does amperage control?
Penetration and burn - off rate of the electrode
Pressure vessels and the piping industry
DCEP (Direct Current Electrode Positive) Reverse Polarity
Dry ice can form within the flow control openings and cause blockage of shielding gas


43. What is the preferred drive roll design for solid wires?
V groove or U groove
Spatter problems and poor weld appearance
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
These terms are quite restrictive and often technically incorrect


44. List several industries that would use GMAW
Push type: Wire is fed by a set of drive rolls located in the wire feed unit - Pull type: Drive rolls mounted in the gun itself - Push- pull type: Combination of the two
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Pressure vessels and the piping industry
3


45. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Penetration and burn - off rate of the electrode
Gives arc voltage values to the control system of the feeder
Duty cycle


46. Why is globular transfer generally avoided with GMAW?
(DCEP) Direct Current Electrode Positive or Reverse polarity
Generally not as accurate
Spatter problems and poor weld appearance
Constant current (CC)


47. List the three methods of metal transfer with GMAW
Gives arc voltage values to the control system of the feeder
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Short- circuiting transfer - Globular transfer - Spray transfer
Puddle fluidity


48. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
To prevent drawing of liquid CO2 (Carbon Dioxide)
If you dont know this check your phone
1/4 inch to 1/2 inch


49. What power sources are used with the GMAW Process?
Motor driven generators - Transformer rectifiers - and Inverter designs
1/4 inch to 1/2 inch
The Arc voltage
Generally not as accurate


50. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Generally not as accurate
Dry ice can form within the flow control openings and cause blockage of shielding gas
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Motor driven generators - Transformer rectifiers - and Inverter designs