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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 wire are knurled drive rolls most commonly used on?
Flux cored wires
12 to 22 arc volts
Gas metal arc welding
The Arc voltage

2. Why is globular transfer generally avoided with GMAW?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
If you dont know this check your phone
Spatter problems and poor weld appearance
Constant voltage (CV)

3. Regulators control_____________ flowmeters SHOW____________.
Pressure - The rate of flow of a shielding gas
(DCEP) Direct Current Electrode Positive or Reverse polarity
The resistace to electrical current flow increases with it. Causing the electrode to heat
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

4. Give a brief description of the GMAW process
Gas metal arc welding
Generally not as accurate
Insufficient current to melt the wire off cleanly
Welding process that joins metals by heating them with an electric arc

5. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
85%
Constant- speed wire feeders and Voltage- sennsing wire feeders
Wire feed speed - Voltage control
Higher 26 to 35 arc volts

6. Draw a typical volt amp curve for a machine that is designed for GMAW
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Guns
12 to 22 arc volts
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

7. Give a description of 'pinch effect'
...
The resistace to electrical current flow increases with it. Causing the electrode to heat
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Minutes of elapsed time continually run (out of 10 minutes)

8. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
The Arc voltage
If you dont know this check your phone
...
Higher 26 to 35 arc volts

9. What is the purpose of the shielding gas used in GMAW?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Shielding the molten weld metal from atmospheric contamination
Minutes of elapsed time continually run (out of 10 minutes)
The negative side of a welding unit

10. With straight polarity where is 2/3 of the arc energy?
Wire feed speed - Voltage control
Penetration and burn - off rate of the electrode
5.8 to 12.5 L/min
The negative side of a welding unit

11. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
Wire feed speed
(DCEP) Direct Current Electrode Positive or Reverse polarity
12 to 22 arc volts
Guns

12. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Cause flaking - which can clog the liner and contact tube
20 to 200 times per second
The time rate of response for the current rise and fall

13. Why must CO2 cylinders be used in the vertical position?
To prevent drawing of liquid CO2 (Carbon Dioxide)
Guns
Controls the rate of flow of a shielding gas to the gun nozzle
Penetration and burn - off rate of the electrode

14. List the basic equipment requirements for the GMAW process
Voltage is the force that overcomes resistance to allow amperage flow
Gas metal arc welding
Constant- speed wire feeders and Voltage- sennsing wire feeders
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

15. What is the required arc voltage used for short circuit transfer?
Guns
12 to 22 arc volts
...
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

16. What controls amperage when using GMAW?
Motor driven generators - Transformer rectifiers - and Inverter designs
Wire feed speed
Gives arc voltage values to the control system of the feeder
15 feet (4.5 meters)

17. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
3
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Short- circuiting transfer - Globular transfer - Spray transfer

18. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Minutes of elapsed time continually run (out of 10 minutes)
85%
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Gives arc voltage values to the control system of the feeder

19. What power sources are used with the GMAW Process?
To prevent drawing of liquid CO2 (Carbon Dioxide)
Welding process that joins metals by heating them with an electric arc
Motor driven generators - Transformer rectifiers - and Inverter designs
When the filler wire is in direct contract with the base metal

20. What are the 2 types of wire feeders available?
Constant- speed wire feeders and Voltage- sennsing wire feeders
DCEP (Direct Current Electrode Positive) Reverse Polarity
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
5.8 to 12.5 L/min

21. What 2 organizations designate specifications for GMAW wires?
Shielding the molten weld metal from atmospheric contamination
Short- circuiting transfer - Globular transfer - Spray transfer
DCEP (Direct Current Electrode Positive) Reverse Polarity
AWS and CSA

22. What happens when the electrode extension is increased?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Aluminum wire
The resistace to electrical current flow increases with it. Causing the electrode to heat
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23. Why is a line heater required when using GMAW?
Puddle fluidity
Dry ice can form within the flow control openings and cause blockage of shielding gas
Guns
Pressure - The rate of flow of a shielding gas

24. What does the term GMAW identify?
AWS and CSA
Speed of the feed motor and - starting / stopping electrode feed
Gas metal arc welding
By there current carrying capacity

25. What effect does increasing and decreasing the inductance have on the weld?
By there current carrying capacity
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Wire feed speed - Voltage control
Spatter problems and poor weld appearance

26. What 2 controls are found on a GMAW set- up?
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Duty cycle
Wire feed speed - Voltage control
Constant current (CC)

27. What is a typical flow rate of CO2 for short circuit transfer?
Cause flaking - which can clog the liner and contact tube
The negative side of a welding unit
AWS and CSA
5.8 to 12.5 L/min

28. Why is a fiber washer required and what cylinder gas requires it?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
To prevent drawing of liquid CO2 (Carbon Dioxide)
V groove or U groove
To prevent leakage - Carbon Dioxide (CO2)

29. How many times per second does short circuiting take place?
Constant- speed wire feeders and Voltage- sennsing wire feeders
20 to 200 times per second
Short- circuiting transfer - Globular transfer - Spray transfer
Generally not as accurate

30. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
The time rate of response for the current rise and fall
Short- circuiting transfer - Globular transfer - Spray transfer
If you dont know this check your phone
Generally not as accurate

31. What current and polarity is generally used with GMAW?
Minutes of elapsed time continually run (out of 10 minutes)
15 feet (4.5 meters)
DCEP (Direct Current Electrode Positive) Reverse Polarity
To prevent leakage - Carbon Dioxide (CO2)

32. In the GMAW process what does voltage control?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
These terms are quite restrictive and often technically incorrect
Puddle fluidity
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

33. List the factors that determine the mode of metal transfer
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Dry ice can form within the flow control openings and cause blockage of shielding gas
Minimum distortion due to low heat input
To prevent leakage - Carbon Dioxide (CO2)

34. What is an advantage of pulsed arc transfer with GMAW?
To prevent drawing of liquid CO2 (Carbon Dioxide)
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
The Arc voltage
12 to 22 arc volts

35. What does voltage do in an electrical circuit?
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
These terms are quite restrictive and often technically incorrect
Voltage is the force that overcomes resistance to allow amperage flow

36. What type of power source is commonly used with a voltage sensing wire feeder?
12 to 22 arc volts
Wire feed speed
The resistace to electrical current flow increases with it. Causing the electrode to heat
Constant current (CC)

37. A 10 minute cycle of welding time vs cooling time a given machine can handle.
3
Minutes of elapsed time continually run (out of 10 minutes)
(DCEP) Direct Current Electrode Positive or Reverse polarity
Duty cycle

38. List 3 forms compressed gases may be supplied for welding
Short- circuiting transfer - Globular transfer - Spray transfer
Gas metal arc welding
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
If you dont know this check your phone

39. What controls the wire speed on a voltage sensing wire feeder?
Spatter problems and poor weld appearance
National Electrical Manufactures Association
The Arc voltage
1/4 inch to 1/2 inch

40. What is a solenoid valve and what actuates it?
Higher 26 to 35 arc volts
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
To prevent drawing of liquid CO2 (Carbon Dioxide)
Reducing the gas source pressure to a constant working pressure

41. A pull type drive system is usually used on what type of material?
Minutes of elapsed time continually run (out of 10 minutes)
Gas metal arc welding
Flux cored wires
Aluminum wire

42. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Higher 26 to 35 arc volts
The time rate of response for the current rise and fall
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
To limit the short circuiting current so that spatter is reduced

43. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Controls the rate of flow of a shielding gas to the gun nozzle
Generally not as accurate
Cause flaking - which can clog the liner and contact tube
85%

44. What is the preferred drive roll design for solid wires?
By there current carrying capacity
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
V groove or U groove
15 feet (4.5 meters)

45. What is the key advantage of short circuiting transfer?
Motor driven generators - Transformer rectifiers - and Inverter designs
Minimum distortion due to low heat input
Wire feed speed - Voltage control
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

46. What is the maximum distance that hard wire can be successfully pushed?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
15 feet (4.5 meters)
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
When the filler wire is in direct contract with the base metal

47. What type of power source is used with a constant speed wire feeder?
Constant voltage (CV)
Constant current (CC)
The time rate of response for the current rise and fall
5.8 to 12.5 L/min

48. What would be an indication that the drive roll pressure is adjusted correctly?
Welding process that joins metals by heating them with an electric arc
Wire feeds smoothly (yet will slip should a problem occur in the gun)
To prevent drawing of liquid CO2 (Carbon Dioxide)
When the filler wire is in direct contract with the base metal

49. What output on the welding machine is used to rate the duty cycle?
These terms are quite restrictive and often technically incorrect
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Minutes of elapsed time continually run (out of 10 minutes)
When the filler wire is in direct contract with the base metal

50. What processes are constant current (CC) power sources designed to be used with?
SMAW - GTAW
Puddle fluidity
National Electrical Manufactures Association
Wire feed speed - Voltage control