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Gas Metal Arc Welding

Instructions:

Answer 50 questions in 15 minutes.
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Match each statement with the correct term.
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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. Why must CO2 cylinders be used in the vertical position?
Controls the rate of flow of a shielding gas to the gun nozzle
Duty cycle
To prevent drawing of liquid CO2 (Carbon Dioxide)
Reducing the gas source pressure to a constant working pressure

2. What is the main purpose of 'slope'?
National Electrical Manufactures Association
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Controls the rate of flow of a shielding gas to the gun nozzle
To limit the short circuiting current so that spatter is reduced

3. What is the effect of too much slope?
Insufficient current to melt the wire off cleanly
Pressure - The rate of flow of a shielding gas
Wire feeds smoothly (yet will slip should a problem occur in the gun)
1/4 inch to 1/2 inch

4. A pull type drive system is usually used on what type of material?
Duty cycle
DCEP (Direct Current Electrode Positive) Reverse Polarity
Aluminum wire
The negative side of a welding unit

5. List 3 wire drive systems and give a short description of each
AWS and CSA
Reducing the gas source pressure to a constant working pressure
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
To prevent drawing of liquid CO2 (Carbon Dioxide)

6. What 2 controls are found on a GMAW set- up?
The negative side of a welding unit
Wire feed speed - Voltage control
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Puddle fluidity

7. What wire are knurled drive rolls most commonly used on?
3
Flux cored wires
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Gas metal arc welding

8. What is a typical flow rate of CO2 for short circuit transfer?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
5.8 to 12.5 L/min
Constant voltage (CV)
Guns

9. Give a brief description of the GMAW process
National Electrical Manufactures Association
Guns
Welding process that joins metals by heating them with an electric arc
Higher 26 to 35 arc volts

10. 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)
To limit the short circuiting current so that spatter is reduced
Higher 26 to 35 arc volts

11. What does inductance control?
Higher 26 to 35 arc volts
DCEP (Direct Current Electrode Positive) Reverse Polarity
The time rate of response for the current rise and fall
(DCEP) Direct Current Electrode Positive or Reverse polarity

12. List the factors that determine the mode of metal transfer
3
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Wire feed speed

13. What is a solenoid valve and what actuates it?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
By there current carrying capacity
Higher 26 to 35 arc volts
Flux cored wires

14. What does a flowmeter do and what does it measure?
85%
Controls the rate of flow of a shielding gas to the gun nozzle
Penetration and burn - off rate of the electrode
Dry ice can form within the flow control openings and cause blockage of shielding gas

15. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
AWS and CSA
Duty cycle
If you dont know this check your phone

16. What is the purpose of the shielding gas used in GMAW?
Constant- speed wire feeders and Voltage- sennsing wire feeders
Higher 26 to 35 arc volts
Wire feed speed
Shielding the molten weld metal from atmospheric contamination

17. What controls amperage when using GMAW?
5.8 to 12.5 L/min
The time rate of response for the current rise and fall
Wire feed speed
Wire feeds smoothly (yet will slip should a problem occur in the gun)

18. What power sources are used with the GMAW Process?
Motor driven generators - Transformer rectifiers - and Inverter designs
5.8 to 12.5 L/min
(DCEP) Direct Current Electrode Positive or Reverse polarity
Penetration and burn - off rate of the electrode

19. What type of power source is used with a constant speed wire feeder?
The time rate of response for the current rise and fall
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Minutes of elapsed time continually run (out of 10 minutes)
Constant voltage (CV)

20. What happens when the electrode extension is increased?
12 to 22 arc volts
The resistace to electrical current flow increases with it. Causing the electrode to heat
Welding process that joins metals by heating them with an electric arc
(DCEP) Direct Current Electrode Positive or Reverse polarity

21. Why is globular transfer generally avoided with GMAW?
Spatter problems and poor weld appearance
85%
The resistace to electrical current flow increases with it. Causing the electrode to heat
Generally not as accurate

22. When is the metal transferred with short circuit transfer?
The Arc voltage
Cause flaking - which can clog the liner and contact tube
When the filler wire is in direct contract with the base metal
Penetration and burn - off rate of the electrode

23. Why is a line heater required when using GMAW?
Dry ice can form within the flow control openings and cause blockage of shielding gas
Wire feed speed - Voltage control
DCEP (Direct Current Electrode Positive) Reverse Polarity
Welding process that joins metals by heating them with an electric arc

24. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
Reducing the gas source pressure to a constant working pressure
The Arc voltage
Wire feed speed
(DCEP) Direct Current Electrode Positive or Reverse polarity

25. What effect does increasing and decreasing the inductance have on the weld?
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
Penetration and burn - off rate of the electrode
Wire feed speed - Voltage control

26. What does the wire feeder control?
AWS and CSA
The time rate of response for the current rise and fall
National Electrical Manufactures Association
Speed of the feed motor and - starting / stopping electrode feed

27. What type of power source is commonly used with a voltage sensing wire feeder?
Spatter problems and poor weld appearance
Pressure vessels and the piping industry
Short- circuiting transfer - Globular transfer - Spray transfer
Constant current (CC)

28. In the GMAW process what does amperage control?
Voltage is the force that overcomes resistance to allow amperage flow
The time rate of response for the current rise and fall
Penetration and burn - off rate of the electrode
The resistace to electrical current flow increases with it. Causing the electrode to heat

29. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
Pressure - The rate of flow of a shielding gas
The Arc voltage
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
85%

30. List 3 forms compressed gases may be supplied for welding
National Electrical Manufactures Association
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Wire feed speed - Voltage control
Wire feed speed

31. What is an advantage of pulsed arc transfer with GMAW?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
3
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

32. With straight polarity where is 2/3 of the arc energy?
The negative side of a welding unit
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Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Penetration and burn - off rate of the electrode

33. Why is the term GMAW preferred over MIG or MAG?
These terms are quite restrictive and often technically incorrect
To prevent leakage - Carbon Dioxide (CO2)
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

34. What current and polarity is generally used with GMAW?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Motor driven generators - Transformer rectifiers - and Inverter designs
To prevent drawing of liquid CO2 (Carbon Dioxide)
To prevent leakage - Carbon Dioxide (CO2)

35. What is the maximum distance that hard wire can be successfully pushed?
12 to 22 arc volts
15 feet (4.5 meters)
Gas metal arc welding
The time rate of response for the current rise and fall

36. What output on the welding machine is used to rate the duty cycle?
Minutes of elapsed time continually run (out of 10 minutes)
Controls the rate of flow of a shielding gas to the gun nozzle
Motor driven generators - Transformer rectifiers - and Inverter designs
DCEP (Direct Current Electrode Positive) Reverse Polarity

37. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
1/4 inch to 1/2 inch
If you dont know this check your phone
(DCEP) Direct Current Electrode Positive or Reverse polarity
Aluminum wire

38. List the basic equipment requirements for the GMAW process
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Motor driven generators - Transformer rectifiers - and Inverter designs
The resistace to electrical current flow increases with it. Causing the electrode to heat
Dry ice can form within the flow control openings and cause blockage of shielding gas

39. What are the 2 types of wire feeders available?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Controls the rate of flow of a shielding gas to the gun nozzle
Constant- speed wire feeders and Voltage- sennsing wire feeders
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

40. What would be an indication that the drive roll pressure is adjusted correctly?
Gas metal arc welding
If you dont know this check your phone
Minimum distortion due to low heat input
Wire feeds smoothly (yet will slip should a problem occur in the gun)

41. What is the key advantage of short circuiting transfer?
Puddle fluidity
If you dont know this check your phone
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Minimum distortion due to low heat input

42. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
Constant- speed wire feeders and Voltage- sennsing wire feeders
3
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
If you dont know this check your phone

43. What processes are constant current (CC) power sources designed to be used with?
Pressure - The rate of flow of a shielding gas
Pressure vessels and the piping industry
Spatter problems and poor weld appearance
SMAW - GTAW

44. What is the disadvantage of the gauge preset type of regulator/flowmeter?
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
Generally not as accurate
Flux cored wires
Controls the rate of flow of a shielding gas to the gun nozzle

45. What does the term GMAW identify?
Constant- speed wire feeders and Voltage- sennsing wire feeders
Gas metal arc welding
3
Minimum distortion due to low heat input

46. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
These terms are quite restrictive and often technically incorrect
Dry ice can form within the flow control openings and cause blockage of shielding gas
Gives arc voltage values to the control system of the feeder
...

47. What does the abbreviation NEMA stand for?
The Arc voltage
Generally not as accurate
DCEP (Direct Current Electrode Positive) Reverse Polarity
National Electrical Manufactures Association

48. What is the preferred drive roll design for solid wires?
Duty cycle
Puddle fluidity
Spatter problems and poor weld appearance
V groove or U groove

49. Draw a typical volt amp curve for a machine that is designed for GMAW
Flux cored wires
Wire feeds smoothly (yet will slip should a problem occur in the gun)
If you dont know this check your phone
These terms are quite restrictive and often technically incorrect

50. Regulators control_____________ flowmeters SHOW____________.
By there current carrying capacity
Shielding the molten weld metal from atmospheric contamination
The time rate of response for the current rise and fall
Pressure - The rate of flow of a shielding gas