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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 does inductance control?
Reducing the gas source pressure to a constant working pressure
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
The time rate of response for the current rise and fall
If you dont know this check your phone

2. List several industries that would use GMAW
These terms are quite restrictive and often technically incorrect
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Puddle fluidity
Pressure vessels and the piping industry

3. A pull type drive system is usually used on what type of material?
85%
5.8 to 12.5 L/min
Aluminum wire
Short- circuiting transfer - Globular transfer - Spray transfer

4. List the three methods of metal transfer with GMAW
Short- circuiting transfer - Globular transfer - Spray transfer
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Motor driven generators - Transformer rectifiers - and Inverter designs
The time rate of response for the current rise and fall

5. What processes are constant current (CC) power sources designed to be used with?
SMAW - GTAW
Welding process that joins metals by heating them with an electric arc
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
To prevent leakage - Carbon Dioxide (CO2)

6. What is the effect of too much slope?
20 to 200 times per second
Minutes of elapsed time continually run (out of 10 minutes)
The time rate of response for the current rise and fall
Insufficient current to melt the wire off cleanly

7. What does the term GMAW identify?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Guns
85%
Gas metal arc welding

8. What is the main purpose of 'slope'?
National Electrical Manufactures Association
Dry ice can form within the flow control openings and cause blockage of shielding gas
To limit the short circuiting current so that spatter is reduced
1/4 inch to 1/2 inch

9. What is the maximum distance that hard wire can be successfully pushed?
15 feet (4.5 meters)
These terms are quite restrictive and often technically incorrect
V groove or U groove
Aluminum wire

10. Give a description of 'pinch effect'
Aluminum wire
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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)

11. Why must CO2 cylinders be used in the vertical position?
By there current carrying capacity
To prevent drawing of liquid CO2 (Carbon Dioxide)
To prevent leakage - Carbon Dioxide (CO2)
V groove or U groove

12. Why is a line heater required when using GMAW?
Welding process that joins metals by heating them with an electric arc
12 to 22 arc volts
Gives arc voltage values to the control system of the feeder
Dry ice can form within the flow control openings and cause blockage of shielding gas

13. What current and polarity is generally used with GMAW?
When the filler wire is in direct contract with the base metal
DCEP (Direct Current Electrode Positive) Reverse Polarity
By there current carrying capacity
Pressure - The rate of flow of a shielding gas

14. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
SMAW - GTAW
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
3
These terms are quite restrictive and often technically incorrect

15. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Duty cycle
3
Aluminum wire

16. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
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Higher 26 to 35 arc volts
The resistace to electrical current flow increases with it. Causing the electrode to heat
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

17. When is the metal transferred with short circuit transfer?
Gas metal arc welding
When the filler wire is in direct contract with the base metal
Wire feed speed - Voltage control
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

18. What 2 controls are found on a GMAW set- up?
Constant- speed wire feeders and Voltage- sennsing wire feeders
Wire feed speed - Voltage control
To prevent drawing of liquid CO2 (Carbon Dioxide)
Pressure vessels and the piping industry

19. With straight polarity where is 2/3 of the arc energy?
Gas metal arc welding
The negative side of a welding unit
AWS and CSA
Constant voltage (CV)

20. How many times per second does short circuiting take place?
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
20 to 200 times per second

21. In the GMAW process what does amperage control?
Cause flaking - which can clog the liner and contact tube
The resistace to electrical current flow increases with it. Causing the electrode to heat
When the filler wire is in direct contract with the base metal
Penetration and burn - off rate of the electrode

22. What does the abbreviation NEMA stand for?
Minutes of elapsed time continually run (out of 10 minutes)
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Penetration and burn - off rate of the electrode
National Electrical Manufactures Association

23. List the factors that determine the mode of metal transfer
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
20 to 200 times per second
Voltage is the force that overcomes resistance to allow amperage flow
(DCEP) Direct Current Electrode Positive or Reverse polarity

24. What is the purpose of the shielding gas used in GMAW?
These terms are quite restrictive and often technically incorrect
Flux cored wires
Shielding the molten weld metal from atmospheric contamination
AWS and CSA

25. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Gives arc voltage values to the control system of the feeder
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
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
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

26. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Cause flaking - which can clog the liner and contact tube
These terms are quite restrictive and often technically incorrect
Aluminum wire
Welding process that joins metals by heating them with an electric arc

27. What output on the welding machine is used to rate the duty cycle?
Minutes of elapsed time continually run (out of 10 minutes)
5.8 to 12.5 L/min
Gives arc voltage values to the control system of the feeder
Pressure - The rate of flow of a shielding gas

28. What is a solenoid valve and what actuates it?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
15 feet (4.5 meters)
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Shielding the molten weld metal from atmospheric contamination

29. What is an advantage of pulsed arc transfer with GMAW?
Short- circuiting transfer - Globular transfer - Spray transfer
85%
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

30. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
If you dont know this check your phone
The Arc voltage
V groove or U groove
12 to 22 arc volts

31. Give a brief description of the GMAW process
Wire feed speed - Voltage control
Cause flaking - which can clog the liner and contact tube
Wire feed speed
Welding process that joins metals by heating them with an electric arc

32. What type of power source is commonly used with a voltage sensing wire feeder?
By there current carrying capacity
Constant current (CC)
When the filler wire is in direct contract with the base metal
Constant- speed wire feeders and Voltage- sennsing wire feeders

33. What is the purpose of a regulator and what does it indicate on its gauges?
Constant current (CC)
85%
DCEP (Direct Current Electrode Positive) Reverse Polarity
Reducing the gas source pressure to a constant working pressure

34. In the GMAW process what does voltage control?
Puddle fluidity
To limit the short circuiting current so that spatter is reduced
Minimum distortion due to low heat input
When the filler wire is in direct contract with the base metal

35. Why is globular transfer generally avoided with 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
Spatter problems and poor weld appearance
Penetration and burn - off rate of the electrode
Controls the rate of flow of a shielding gas to the gun nozzle

36. What controls amperage when using GMAW?
Controls the rate of flow of a shielding gas to the gun nozzle
20 to 200 times per second
Wire feed speed
To prevent leakage - Carbon Dioxide (CO2)

37. What controls the wire speed on a voltage sensing wire feeder?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
The negative side of a welding unit
To prevent drawing of liquid CO2 (Carbon Dioxide)
The Arc voltage

38. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
DCEP (Direct Current Electrode Positive) Reverse Polarity
5.8 to 12.5 L/min
85%

39. List the basic equipment requirements for the GMAW process
Flux cored wires
The Arc voltage
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Duty cycle

40. What is the recommended electrode stick- out for .035 solid wire?
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
1/4 inch to 1/2 inch
The resistace to electrical current flow increases with it. Causing the electrode to heat

41. What 2 organizations designate specifications for GMAW wires?
Wire feed speed
AWS and CSA
Constant current (CC)
Gives arc voltage values to the control system of the feeder

42. What type of power source is used with a constant speed wire feeder?
If you dont know this check your phone
5.8 to 12.5 L/min
National Electrical Manufactures Association
Constant voltage (CV)

43. What is the preferred drive roll design for solid wires?
Minimum distortion due to low heat input
V groove or U groove
By there current carrying capacity
Motor driven generators - Transformer rectifiers - and Inverter designs

44. What is the key advantage of short circuiting transfer?
Motor driven generators - Transformer rectifiers - and Inverter designs
Minimum distortion due to low heat input
The time rate of response for the current rise and fall
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

45. What power sources are used with the GMAW Process?
1/4 inch to 1/2 inch
Minutes of elapsed time continually run (out of 10 minutes)
V groove or U groove
Motor driven generators - Transformer rectifiers - and Inverter designs

46. List 3 forms compressed gases may be supplied for welding
Controls the rate of flow of a shielding gas to the gun nozzle
Reducing the gas source pressure to a constant working pressure
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

47. What does a flowmeter do and what does it measure?
Controls the rate of flow of a shielding gas to the gun nozzle
To prevent leakage - Carbon Dioxide (CO2)
V groove or U groove
Wire feeds smoothly (yet will slip should a problem occur in the gun)

48. Why is a fiber washer required and what cylinder gas requires it?
Shielding the molten weld metal from atmospheric contamination
SMAW - GTAW
To prevent leakage - Carbon Dioxide (CO2)
12 to 22 arc volts

49. What is a typical flow rate of CO2 for short circuit transfer?
Controls the rate of flow of a shielding gas to the gun nozzle
(DCEP) Direct Current Electrode Positive or Reverse polarity
Motor driven generators - Transformer rectifiers - and Inverter designs
5.8 to 12.5 L/min

50. What wire are knurled drive rolls most commonly used on?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
85%
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
Flux cored wires