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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. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Constant- speed wire feeders and Voltage- sennsing wire feeders
Generally not as accurate
To prevent drawing of liquid CO2 (Carbon Dioxide)
Motor driven generators - Transformer rectifiers - and Inverter designs

2. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
Reducing the gas source pressure to a constant working pressure
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
(DCEP) Direct Current Electrode Positive or Reverse polarity
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3. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
Pressure vessels and the piping industry
5.8 to 12.5 L/min
Constant voltage (CV)
...

4. Why is a line heater required when using GMAW?
To prevent leakage - Carbon Dioxide (CO2)
Dry ice can form within the flow control openings and cause blockage of shielding gas
Shielding the molten weld metal from atmospheric contamination
SMAW - GTAW

5. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
Wire feed speed
The time rate of response for the current rise and fall
Flux cored wires
85%

6. What is the required arc voltage used for short circuit transfer?
12 to 22 arc volts
Penetration and burn - off rate of the electrode
SMAW - GTAW
Motor driven generators - Transformer rectifiers - and Inverter designs

7. What 2 organizations designate specifications for GMAW wires?
Duty cycle
AWS and CSA
Wire feed speed - Voltage control
Cause flaking - which can clog the liner and contact tube

8. What does a flowmeter do and what does it measure?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Pressure - The rate of flow of a shielding gas
Short- circuiting transfer - Globular transfer - Spray transfer
Controls the rate of flow of a shielding gas to the gun nozzle

9. List the three methods of metal transfer with GMAW
Short- circuiting transfer - Globular transfer - Spray transfer
20 to 200 times per second
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Cause flaking - which can clog the liner and contact tube

10. How are GMAW guns rated?
By there current carrying capacity
15 feet (4.5 meters)
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Pressure - The rate of flow of a shielding gas

11. Give a description of 'pinch effect'
Duty cycle
To limit the short circuiting current so that spatter is reduced
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Pressure - The rate of flow of a shielding gas

12. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
Constant current (CC)
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
National Electrical Manufactures Association
3

13. Give a brief description of the GMAW process
Spatter problems and poor weld appearance
The Arc voltage
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Welding process that joins metals by heating them with an electric arc

14. What would be an indication that the drive roll pressure is adjusted correctly?
The resistace to electrical current flow increases with it. Causing the electrode to heat
Reducing the gas source pressure to a constant working pressure
To prevent drawing of liquid CO2 (Carbon Dioxide)
Wire feeds smoothly (yet will slip should a problem occur in the gun)

15. Draw a typical volt amp curve for a machine that is designed for GMAW
If you dont know this check your phone
Reducing the gas source pressure to a constant working pressure
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Flux cored wires

16. What does inductance control?
The time rate of response for the current rise and fall
If you dont know this check your phone
15 feet (4.5 meters)
To prevent drawing of liquid CO2 (Carbon Dioxide)

17. What 2 controls are found on a GMAW set- up?
Cause flaking - which can clog the liner and contact tube
(DCEP) Direct Current Electrode Positive or Reverse polarity
Wire feed speed - Voltage control
To limit the short circuiting current so that spatter is reduced

18. What is the main purpose of 'slope'?
To limit the short circuiting current so that spatter is reduced
(DCEP) Direct Current Electrode Positive or Reverse polarity
If you dont know this check your phone
SMAW - GTAW

19. List the factors that determine the mode of metal transfer
20 to 200 times per second
The Arc voltage
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Aluminum wire

20. What type of power source is used with a constant speed wire feeder?
Controls the rate of flow of a shielding gas to the gun nozzle
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Constant voltage (CV)
If you dont know this check your phone

21. A pull type drive system is usually used on what type of material?
These terms are quite restrictive and often technically incorrect
Aluminum wire
To prevent drawing of liquid CO2 (Carbon Dioxide)
Shielding the molten weld metal from atmospheric contamination

22. In the GMAW process what does voltage control?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Dry ice can form within the flow control openings and cause blockage of shielding gas
3
Puddle fluidity

23. What power sources are used with the GMAW Process?
Wire feed speed
(DCEP) Direct Current Electrode Positive or Reverse polarity
1/4 inch to 1/2 inch
Motor driven generators - Transformer rectifiers - and Inverter designs

24. What does the wire feeder control?
Gas metal arc welding
15 feet (4.5 meters)
Speed of the feed motor and - starting / stopping electrode feed
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

25. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
Penetration and burn - off rate of the electrode
(DCEP) Direct Current Electrode Positive or Reverse polarity
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
3

26. In the GMAW process what does amperage control?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Penetration and burn - off rate of the electrode
The resistace to electrical current flow increases with it. Causing the electrode to heat
Puddle fluidity

27. What is the purpose of the shielding gas used in GMAW?
Shielding the molten weld metal from atmospheric contamination
1/4 inch to 1/2 inch
To prevent leakage - Carbon Dioxide (CO2)
DCEP (Direct Current Electrode Positive) Reverse Polarity

28. What effect does increasing and decreasing the inductance have on the weld?
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Constant voltage (CV)
5.8 to 12.5 L/min
The time rate of response for the current rise and fall

29. What does the abbreviation NEMA stand for?
National Electrical Manufactures Association
By there current carrying capacity
Wire feed speed - Voltage control
Short- circuiting transfer - Globular transfer - Spray transfer

30. What is the maximum distance that hard wire can be successfully pushed?
Constant voltage (CV)
AWS and CSA
The resistace to electrical current flow increases with it. Causing the electrode to heat
15 feet (4.5 meters)

31. What is a typical flow rate of CO2 for short circuit transfer?
Penetration and burn - off rate of the electrode
5.8 to 12.5 L/min
DCEP (Direct Current Electrode Positive) Reverse Polarity
Higher 26 to 35 arc volts

32. What does the term GMAW identify?
Puddle fluidity
By there current carrying capacity
Higher 26 to 35 arc volts
Gas metal arc welding

33. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Higher 26 to 35 arc volts
The resistace to electrical current flow increases with it. Causing the electrode to heat
Gives arc voltage values to the control system of the feeder
(DCEP) Direct Current Electrode Positive or Reverse polarity

34. Why is a fiber washer required and what cylinder gas requires it?
Speed of the feed motor and - starting / stopping electrode feed
To prevent leakage - Carbon Dioxide (CO2)
Minutes of elapsed time continually run (out of 10 minutes)
Dry ice can form within the flow control openings and cause blockage of shielding gas

35. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Aluminum wire
Cause flaking - which can clog the liner and contact tube
Generally not as accurate
To prevent drawing of liquid CO2 (Carbon Dioxide)

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

37. Why is the term GMAW preferred over MIG or MAG?
These terms are quite restrictive and often technically incorrect
To limit the short circuiting current so that spatter is reduced
1/4 inch to 1/2 inch
Insufficient current to melt the wire off cleanly

38. Why must CO2 cylinders be used in the vertical position?
These terms are quite restrictive and often technically incorrect
V groove or U groove
To prevent drawing of liquid CO2 (Carbon Dioxide)
When the filler wire is in direct contract with the base metal

39. What is an advantage of pulsed arc transfer with GMAW?
When the filler wire is in direct contract with the base metal
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Higher 26 to 35 arc volts

40. What is the effect of too much slope?
Motor driven generators - Transformer rectifiers - and Inverter designs
...
Insufficient current to melt the wire off cleanly
20 to 200 times per second

41. What is the recommended electrode stick- out for .035 solid wire?
5.8 to 12.5 L/min
3
1/4 inch to 1/2 inch
Wire feeds smoothly (yet will slip should a problem occur in the gun)

42. What is the preferred drive roll design for solid wires?
15 feet (4.5 meters)
Guns
V groove or U groove
DCEP (Direct Current Electrode Positive) Reverse Polarity

43. List several industries that would use GMAW
Puddle fluidity
Gives arc voltage values to the control system of the feeder
Pressure vessels and the piping industry
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

44. What happens when the electrode extension is increased?
When the filler wire is in direct contract with the base metal
If you dont know this check your phone
If you dont know this check your phone
The resistace to electrical current flow increases with it. Causing the electrode to heat

45. What controls the wire speed on a voltage sensing wire feeder?
Duty cycle
The Arc voltage
3
Higher 26 to 35 arc volts

46. Regulators control_____________ flowmeters SHOW____________.
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 - The rate of flow of a shielding gas
Generally not as accurate
15 feet (4.5 meters)

47. A 10 minute cycle of welding time vs cooling time a given machine can handle.
When the filler wire is in direct contract with the base metal
Pressure - The rate of flow of a shielding gas
Duty cycle
Constant current (CC)

48. What controls amperage when using GMAW?
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Minutes of elapsed time continually run (out of 10 minutes)
Wire feed speed
Cause flaking - which can clog the liner and contact tube

49. What is a solenoid valve and what actuates it?
12 to 22 arc volts
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Spatter problems and poor weld appearance
If you dont know this check your phone

50. What does voltage do in an electrical circuit?
Voltage is the force that overcomes resistance to allow amperage flow
Constant voltage (CV)
(DCEP) Direct Current Electrode Positive or Reverse polarity
Dry ice can form within the flow control openings and cause blockage of shielding gas