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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 is a line heater required when using GMAW?
Dry ice can form within the flow control openings and cause blockage of shielding gas
15 feet (4.5 meters)
National Electrical Manufactures Association
Welding process that joins metals by heating them with an electric arc

2. What wire are knurled drive rolls most commonly used on?
Shielding the molten weld metal from atmospheric contamination
The resistace to electrical current flow increases with it. Causing the electrode to heat
Flux cored wires
To limit the short circuiting current so that spatter is reduced

3. What is the key advantage of short circuiting transfer?
Minimum distortion due to low heat input
To prevent leakage - Carbon Dioxide (CO2)
Higher 26 to 35 arc volts
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

4. What is an advantage of pulsed arc transfer with GMAW?
Shielding the molten weld metal from atmospheric contamination
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
Guns

5. 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
20 to 200 times per second
By there current carrying capacity

6. What processes are constant current (CC) power sources designed to be used with?
SMAW - GTAW
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
To limit the short circuiting current so that spatter is reduced
Flux cored wires

7. What power sources are used with the GMAW Process?
1/4 inch to 1/2 inch
Motor driven generators - Transformer rectifiers - and Inverter designs
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
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

8. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Insufficient current to melt the wire off cleanly
Gives arc voltage values to the control system of the feeder
Motor driven generators - Transformer rectifiers - and Inverter designs
Gas metal arc welding

9. What type of power source is commonly used with a voltage sensing wire feeder?
Aluminum wire
Constant current (CC)
1/4 inch to 1/2 inch
3

10. What is a solenoid valve and what actuates it?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Motor driven generators - Transformer rectifiers - and Inverter designs
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Welding process that joins metals by heating them with an electric arc

11. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
3
Dry ice can form within the flow control openings and cause blockage of shielding gas
Penetration and burn - off rate of the electrode
Aluminum wire

12. List the three methods of metal transfer with GMAW
Penetration and burn - off rate of the electrode
Short- circuiting transfer - Globular transfer - Spray transfer
Spatter problems and poor weld appearance
...

13. List the basic equipment requirements for the GMAW process
Short- circuiting transfer - Globular transfer - Spray transfer
Flux cored wires
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Reducing the gas source pressure to a constant working pressure

14. What does a flowmeter do and what does it measure?
These terms are quite restrictive and often technically incorrect
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Controls the rate of flow of a shielding gas to the gun nozzle
12 to 22 arc volts

15. How are GMAW guns rated?
The Arc voltage
By there current carrying capacity
When the filler wire is in direct contract with the base metal
The time rate of response for the current rise and fall

16. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Duty cycle
Motor driven generators - Transformer rectifiers - and Inverter designs
Pressure vessels and the piping industry
Generally not as accurate

17. How many times per second does short circuiting take place?
20 to 200 times per second
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Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Generally not as accurate

18. List the factors that determine the mode of metal transfer
V groove or U groove
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
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. List 3 forms compressed gases may be supplied for welding
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
To prevent drawing of liquid CO2 (Carbon Dioxide)
The resistace to electrical current flow increases with it. Causing the electrode to heat
Pressure vessels and the piping industry

20. What is the purpose of a regulator and what does it indicate on its gauges?
Cause flaking - which can clog the liner and contact tube
1/4 inch to 1/2 inch
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Reducing the gas source pressure to a constant working pressure

21. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
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...
DCEP (Direct Current Electrode Positive) Reverse Polarity
Wire feed speed

22. What happens when the electrode extension is increased?
Dry ice can form within the flow control openings and cause blockage of shielding gas
Insufficient current to melt the wire off cleanly
Short- circuiting transfer - Globular transfer - Spray transfer
The resistace to electrical current flow increases with it. Causing the electrode to heat

23. What 2 controls are found on a GMAW set- up?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
DCEP (Direct Current Electrode Positive) Reverse Polarity
The negative side of a welding unit
Wire feed speed - Voltage control

24. What controls the wire speed on a voltage sensing wire feeder?
Generally not as accurate
Controls the rate of flow of a shielding gas to the gun nozzle
...
The Arc voltage

25. What controls amperage when using GMAW?
Wire feed speed
Generally not as accurate
85%
Insufficient current to melt the wire off cleanly

26. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Motor driven generators - Transformer rectifiers - and Inverter designs
5.8 to 12.5 L/min
Spatter problems and poor weld appearance
Duty cycle

27. Why is the term GMAW preferred over MIG or MAG?
These terms are quite restrictive and often technically incorrect
Minimum distortion due to low heat input
5.8 to 12.5 L/min
If you dont know this check your phone

28. 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
Insufficient current to melt the wire off cleanly
5.8 to 12.5 L/min
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

29. What type of power source is used with a constant speed wire feeder?
Duty cycle
Constant voltage (CV)
Penetration and burn - off rate of the electrode
(DCEP) Direct Current Electrode Positive or Reverse polarity

30. What is the effect of too much slope?
To prevent drawing of liquid CO2 (Carbon Dioxide)
Insufficient current to melt the wire off cleanly
If you dont know this check your phone
Constant current (CC)

31. What does inductance control?
V groove or U groove
85%
The time rate of response for the current rise and fall
Constant- speed wire feeders and Voltage- sennsing wire feeders

32. With straight polarity where is 2/3 of the arc energy?
The negative side of a welding unit
Flux cored wires
Short- circuiting transfer - Globular transfer - Spray transfer
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

33. What does the abbreviation NEMA stand for?
Shielding the molten weld metal from atmospheric contamination
Motor driven generators - Transformer rectifiers - and Inverter designs
National Electrical Manufactures Association
By there current carrying capacity

34. What does voltage do in an electrical circuit?
Minimum distortion due to low heat input
Voltage is the force that overcomes resistance to allow amperage flow
Spatter problems and poor weld appearance
20 to 200 times per second

35. In the GMAW process what does voltage control?
Puddle fluidity
Aluminum wire
12 to 22 arc volts
...

36. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Cause flaking - which can clog the liner and contact tube
Constant- speed wire feeders and Voltage- sennsing wire feeders
Pressure - The rate of flow of a shielding gas

37. A pull type drive system is usually used on what type of material?
When the filler wire is in direct contract with the base metal
Cause flaking - which can clog the liner and contact tube
Aluminum wire
DCEP (Direct Current Electrode Positive) Reverse Polarity

38. Why is globular transfer generally avoided with GMAW?
Generally not as accurate
3
Spatter problems and poor weld appearance
15 feet (4.5 meters)

39. List 3 wire drive systems and give a short description of each
Voltage is the force that overcomes resistance to allow amperage flow
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
(DCEP) Direct Current Electrode Positive or Reverse polarity
National Electrical Manufactures Association

40. List several industries that would use GMAW
These terms are quite restrictive and often technically incorrect
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
If you dont know this check your phone
Pressure vessels and the piping industry

41. What is another term for electrode holders for GMAW?
Pressure - The rate of flow of a shielding gas
Guns
Constant voltage (CV)
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

42. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
If you dont know this check your phone
Reducing the gas source pressure to a constant working pressure
Wire feeds smoothly (yet will slip should a problem occur in the gun)
...

43. What is the required arc voltage used for short circuit transfer?
3
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The negative side of a welding unit
12 to 22 arc volts

44. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Duty cycle
Welding process that joins metals by heating them with an electric arc
Higher 26 to 35 arc volts
National Electrical Manufactures Association

45. Why must CO2 cylinders be used in the vertical position?
Gives arc voltage values to the control system of the feeder
To prevent drawing of liquid CO2 (Carbon Dioxide)
Wire feed speed
If you dont know this check your phone

46. What would be an indication that the drive roll pressure is adjusted correctly?
Minutes of elapsed time continually run (out of 10 minutes)
Shielding the molten weld metal from atmospheric contamination
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Wire feeds smoothly (yet will slip should a problem occur in the gun)

47. Give a description of 'pinch effect'
Motor driven generators - Transformer rectifiers - and Inverter designs
AWS and CSA
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

48. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
5.8 to 12.5 L/min
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
85%
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

49. What are the 2 types of wire feeders available?
Higher 26 to 35 arc volts
Constant- speed wire feeders and Voltage- sennsing wire feeders
Dry ice can form within the flow control openings and cause blockage of shielding gas
Duty cycle

50. What output on the welding machine is used to rate the duty cycle?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Wire feed speed - Voltage control
Minutes of elapsed time continually run (out of 10 minutes)
Controls the rate of flow of a shielding gas to the gun nozzle