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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 type of power source is used with a constant speed wire feeder?
Guns
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Constant voltage (CV)
Wire feed speed - Voltage control

2. What processes are constant current (CC) power sources designed to be used with?
85%
SMAW - GTAW
5.8 to 12.5 L/min
Welding process that joins metals by heating them with an electric arc

3. What is the recommended electrode stick- out for .035 solid wire?
1/4 inch to 1/2 inch
Wire feed speed
Pressure - The rate of flow of a shielding gas
Dry ice can form within the flow control openings and cause blockage of shielding gas

4. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
To prevent drawing of liquid CO2 (Carbon Dioxide)
Wire feed speed - Voltage control
DCEP (Direct Current Electrode Positive) Reverse Polarity
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5. Give a brief description of the GMAW process
Reducing the gas source pressure to a constant working pressure
The time rate of response for the current rise and fall
Welding process that joins metals by heating them with an electric arc
Constant current (CC)

6. List 3 wire drive systems and give a short description of each
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
Controls the rate of flow of a shielding gas to the gun nozzle
Gives arc voltage values to the control system of the feeder
1/4 inch to 1/2 inch

7. How are GMAW guns rated?
85%
By there current carrying capacity
To limit the short circuiting current so that spatter is reduced
Voltage is the force that overcomes resistance to allow amperage flow

8. What is the main purpose of 'slope'?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
20 to 200 times per second
To limit the short circuiting current so that spatter is reduced
Short- circuiting transfer - Globular transfer - Spray transfer

9. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
Constant voltage (CV)
When the filler wire is in direct contract with the base metal
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

10. What is another term for electrode holders for GMAW?
Constant voltage (CV)
Wire feed speed - Voltage control
Guns
Minimum distortion due to low heat input

11. List several industries that would use GMAW
Controls the rate of flow of a shielding gas to the gun nozzle
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Pressure vessels and the piping industry
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

12. What does voltage do in an electrical circuit?
Voltage is the force that overcomes resistance to allow amperage flow
DCEP (Direct Current Electrode Positive) Reverse Polarity
12 to 22 arc volts
Minimum distortion due to low heat input

13. What are the 2 types of wire feeders available?
To prevent leakage - Carbon Dioxide (CO2)
Minimum distortion due to low heat input
Constant- speed wire feeders and Voltage- sennsing wire feeders
Flux cored wires

14. In the GMAW process what does amperage control?
Penetration and burn - off rate of the electrode
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Spatter problems and poor weld appearance
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

15. Draw a typical volt amp curve for a machine that is designed for GMAW
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3
The time rate of response for the current rise and fall
Short- circuiting transfer - Globular transfer - Spray transfer

16. What is the required arc voltage used for short circuit transfer?
1/4 inch to 1/2 inch
Wire feed speed - Voltage control
Reducing the gas source pressure to a constant working pressure
12 to 22 arc volts

17. What is the key advantage of short circuiting transfer?
Insufficient current to melt the wire off cleanly
Minimum distortion due to low heat input
These terms are quite restrictive and often technically incorrect
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

18. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Speed of the feed motor and - starting / stopping electrode feed
Pressure vessels and the piping industry
Duty cycle
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19. Why is the term GMAW preferred over MIG or MAG?
These terms are quite restrictive and often technically incorrect
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Aluminum wire
To prevent drawing of liquid CO2 (Carbon Dioxide)

20. What does the abbreviation NEMA stand for?
Speed of the feed motor and - starting / stopping electrode feed
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
National Electrical Manufactures Association
To prevent drawing of liquid CO2 (Carbon Dioxide)

21. 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
Voltage is the force that overcomes resistance to allow amperage flow
AWS and CSA
Constant voltage (CV)

22. What controls amperage when using GMAW?
85%
Wire feed speed
The negative side of a welding unit
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

23. What wire are knurled drive rolls most commonly used on?
To prevent drawing of liquid CO2 (Carbon Dioxide)
These terms are quite restrictive and often technically incorrect
Motor driven generators - Transformer rectifiers - and Inverter designs
Flux cored wires

24. What current and polarity is generally used with GMAW?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Puddle fluidity
Voltage is the force that overcomes resistance to allow amperage flow
Aluminum wire

25. What does the wire feeder control?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Spatter problems and poor weld appearance
Gives arc voltage values to the control system of the feeder
Speed of the feed motor and - starting / stopping electrode feed

26. List 3 forms compressed gases may be supplied for welding
By there current carrying capacity
The Arc voltage
15 feet (4.5 meters)
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

27. What is the effect of too much slope?
Constant voltage (CV)
Insufficient current to melt the wire off cleanly
Duty cycle
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

28. What happens when the electrode extension is increased?
Pressure vessels and the piping industry
3
The resistace to electrical current flow increases with it. Causing the electrode to heat
V groove or U groove

29. List the three methods of metal transfer with GMAW
SMAW - GTAW
Reducing the gas source pressure to a constant working pressure
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Short- circuiting transfer - Globular transfer - Spray transfer

30. What is a typical flow rate of CO2 for short circuit transfer?
(DCEP) Direct Current Electrode Positive or Reverse polarity
Motor driven generators - Transformer rectifiers - and Inverter designs
5.8 to 12.5 L/min
To prevent leakage - Carbon Dioxide (CO2)

31. What does a flowmeter do and what does it measure?
Pressure - The rate of flow of a shielding gas
Controls the rate of flow of a shielding gas to the gun nozzle
1/4 inch to 1/2 inch
Higher 26 to 35 arc volts

32. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
To prevent leakage - Carbon Dioxide (CO2)
3
Minimum distortion due to low heat input
Wire feed speed

33. What is the purpose of the shielding gas used in GMAW?
Wire feed speed - Voltage control
Puddle fluidity
Shielding the molten weld metal from atmospheric contamination
By there current carrying capacity

34. Why must CO2 cylinders be used in the vertical position?
Generally not as accurate
To prevent drawing of liquid CO2 (Carbon Dioxide)
AWS and CSA
Duty cycle

35. What type of power source is commonly used with a voltage sensing wire feeder?
Constant current (CC)
Generally not as accurate
By there current carrying capacity
(DCEP) Direct Current Electrode Positive or Reverse polarity

36. What does inductance control?
Motor driven generators - Transformer rectifiers - and Inverter designs
The time rate of response for the current rise and fall
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Minutes of elapsed time continually run (out of 10 minutes)

37. What effect does increasing and decreasing the inductance have on the weld?
By there current carrying capacity
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
Guns

38. What controls the wire speed on a voltage sensing wire feeder?
The Arc voltage
When the filler wire is in direct contract with the base metal
If you dont know this check your phone
Dry ice can form within the flow control openings and cause blockage of shielding gas

39. What is the preferred drive roll design for solid wires?
Puddle fluidity
(DCEP) Direct Current Electrode Positive or Reverse polarity
V groove or U groove
3

40. What 2 organizations designate specifications for GMAW wires?
Wire feed speed
To prevent drawing of liquid CO2 (Carbon Dioxide)
Higher 26 to 35 arc volts
AWS and CSA

41. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Generally not as accurate
Cause flaking - which can clog the liner and contact tube
Gas metal arc welding
Constant current (CC)

42. List the basic equipment requirements for the GMAW process
15 feet (4.5 meters)
1/4 inch to 1/2 inch
Constant current (CC)
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

43. Regulators control_____________ flowmeters SHOW____________.
Puddle fluidity
Dry ice can form within the flow control openings and cause blockage of shielding gas
Pressure - The rate of flow of a shielding gas
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

44. What is the purpose of a regulator and what does it indicate on its gauges?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Reducing the gas source pressure to a constant working pressure
Minimum distortion due to low heat input
3

45. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
85%
Higher 26 to 35 arc volts
Insufficient current to melt the wire off cleanly
1/4 inch to 1/2 inch

46. What would be an indication that the drive roll pressure is adjusted correctly?
3
Wire feeds smoothly (yet will slip should a problem occur in the gun)
When the filler wire is in direct contract with the base metal
Wire feed speed

47. A pull type drive system is usually used on what type of material?
Dry ice can form within the flow control openings and cause blockage of shielding gas
The resistace to electrical current flow increases with it. Causing the electrode to heat
Aluminum wire
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

48. What is an advantage of pulsed arc transfer with GMAW?
Minutes of elapsed time continually run (out of 10 minutes)
85%
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
V groove or U groove

49. What output on the welding machine is used to rate the duty cycle?
Generally not as accurate
To prevent leakage - Carbon Dioxide (CO2)
Minutes of elapsed time continually run (out of 10 minutes)
Wire feed speed - Voltage control

50. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
...
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field