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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. List several industries that would use GMAW
Pressure - The rate of flow of a shielding gas
Penetration and burn - off rate of the electrode
SMAW - GTAW
Pressure vessels and the piping industry

2. What does the wire feeder control?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Speed of the feed motor and - starting / stopping electrode feed
To limit the short circuiting current so that spatter is reduced
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

3. How many times per second does short circuiting take place?
20 to 200 times per second
Motor driven generators - Transformer rectifiers - and Inverter designs
The negative side of a welding unit
Welding process that joins metals by heating them with an electric arc

4. What type of power source is used with a constant speed wire feeder?
Constant voltage (CV)
To prevent drawing of liquid CO2 (Carbon Dioxide)
15 feet (4.5 meters)
The resistace to electrical current flow increases with it. Causing the electrode to heat

5. What does the term GMAW identify?
Flux cored wires
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Gas metal arc welding
The resistace to electrical current flow increases with it. Causing the electrode to heat

6. What is a typical flow rate of CO2 for short circuit transfer?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
5.8 to 12.5 L/min
AWS and CSA
12 to 22 arc volts

7. What does the abbreviation NEMA stand for?
15 feet (4.5 meters)
National Electrical Manufactures Association
5.8 to 12.5 L/min
20 to 200 times per second

8. What is an advantage of pulsed arc transfer with GMAW?
Pressure - The rate of flow of a shielding gas
By there current carrying capacity
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) Reverse Polarity

9. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
3
Higher 26 to 35 arc volts
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- speed wire feeders and Voltage- sennsing wire feeders

10. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Duty cycle
Flux cored wires
Speed of the feed motor and - starting / stopping electrode feed
To prevent drawing of liquid CO2 (Carbon Dioxide)

11. What power sources are used with the GMAW Process?
National Electrical Manufactures Association
DCEP (Direct Current Electrode Positive) Reverse Polarity
Spatter problems and poor weld appearance
Motor driven generators - Transformer rectifiers - and Inverter designs

12. What does a flowmeter do and what does it measure?
If you dont know this check your phone
Controls the rate of flow of a shielding gas to the gun nozzle
Constant voltage (CV)
Dry ice can form within the flow control openings and cause blockage of shielding gas

13. A pull type drive system is usually used on what type of material?
12 to 22 arc volts
The Arc voltage
(DCEP) Direct Current Electrode Positive or Reverse polarity
Aluminum wire

14. Regulators control_____________ flowmeters SHOW____________.
Higher 26 to 35 arc volts
When the filler wire is in direct contract with the base metal
Pressure - The rate of flow of a shielding gas
Short- circuiting transfer - Globular transfer - Spray transfer

15. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
To prevent leakage - Carbon Dioxide (CO2)
...
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
5.8 to 12.5 L/min

16. List the three methods of metal transfer with GMAW
Short- circuiting transfer - Globular transfer - Spray transfer
Constant current (CC)
Controls the rate of flow of a shielding gas to the gun nozzle
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

17. What is the main purpose of 'slope'?
1/4 inch to 1/2 inch
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
3
To limit the short circuiting current so that spatter is reduced

18. What is the required arc voltage used for short circuit transfer?
Welding process that joins metals by heating them with an electric arc
12 to 22 arc volts
Minutes of elapsed time continually run (out of 10 minutes)
1/4 inch to 1/2 inch

19. How are GMAW guns rated?
...
By there current carrying capacity
Constant- speed wire feeders and Voltage- sennsing wire feeders
Short- circuiting transfer - Globular transfer - Spray transfer

20. List the basic equipment requirements for the GMAW process
Shielding the molten weld metal from atmospheric contamination
National Electrical Manufactures Association
Pressure - The rate of flow of a shielding gas
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

21. What is the purpose of the shielding gas used in GMAW?
Higher 26 to 35 arc volts
Welding process that joins metals by heating them with an electric arc
Shielding the molten weld metal from atmospheric contamination
Dry ice can form within the flow control openings and cause blockage of shielding gas

22. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
AWS and CSA
Gives arc voltage values to the control system of the feeder
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
1/4 inch to 1/2 inch

23. Why is the term GMAW preferred over MIG or MAG?
These terms are quite restrictive and often technically incorrect
SMAW - GTAW
Shielding the molten weld metal from atmospheric contamination
(DCEP) Direct Current Electrode Positive or Reverse polarity

24. What is the key advantage of short circuiting transfer?
...
If you dont know this check your phone
Minimum distortion due to low heat input
Wire feed speed

25. What processes are constant current (CC) power sources designed to be used with?
SMAW - GTAW
Flux cored wires
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
The resistace to electrical current flow increases with it. Causing the electrode to heat

26. What is a solenoid valve and what actuates it?
Minimum distortion due to low heat input
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
Aluminum wire

27. In the GMAW process what does amperage control?
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
Penetration and burn - off rate of the electrode
Controls the rate of flow of a shielding gas to the gun nozzle
3

28. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Generally not as accurate
Motor driven generators - Transformer rectifiers - and Inverter designs
5.8 to 12.5 L/min
Pressure vessels and the piping industry

29. What 2 organizations designate specifications for GMAW wires?
When the filler wire is in direct contract with the base metal
Short- circuiting transfer - Globular transfer - Spray transfer
AWS and CSA
V groove or U groove

30. In the GMAW process what does voltage control?
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
Pressure vessels and the piping industry
Puddle fluidity
1/4 inch to 1/2 inch

31. What wire are knurled drive rolls most commonly used on?
Penetration and burn - off rate of the electrode
Flux cored wires
The resistace to electrical current flow increases with it. Causing the electrode to heat
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

32. Give a description of 'pinch effect'
85%
The Arc voltage
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
SMAW - GTAW

33. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
Flux cored wires
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
3
Cause flaking - which can clog the liner and contact tube

34. Give a brief description of the GMAW process
Welding process that joins metals by heating them with an electric arc
If you dont know this check your phone
...
To prevent leakage - Carbon Dioxide (CO2)

35. What controls amperage when using GMAW?
Wire feed speed
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
12 to 22 arc volts
These terms are quite restrictive and often technically incorrect

36. What are the 2 types of wire feeders available?
Constant- speed wire feeders and Voltage- sennsing wire feeders
These terms are quite restrictive and often technically incorrect
If you dont know this check your phone
Reducing the gas source pressure to a constant working pressure

37. What controls the wire speed on a voltage sensing wire feeder?
Wire feed speed
Aluminum wire
The Arc voltage
Puddle fluidity

38. Why is globular transfer generally avoided with GMAW?
Spatter problems and poor weld appearance
SMAW - GTAW
Short- circuiting transfer - Globular transfer - Spray transfer
Dry ice can form within the flow control openings and cause blockage of shielding gas

39. What is the minimum % value of argon that must be present to use the spray transfer method of 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
Pressure - The rate of flow of a shielding gas
These terms are quite restrictive and often technically incorrect
85%

40. List 3 wire drive systems and give a short description of each
Pressure vessels and the piping industry
Guns
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
National Electrical Manufactures Association

41. What does voltage do in an electrical circuit?
Generally not as accurate
If you dont know this check your phone
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Voltage is the force that overcomes resistance to allow amperage flow

42. What is the maximum distance that hard wire can be successfully pushed?
15 feet (4.5 meters)
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Minutes of elapsed time continually run (out of 10 minutes)
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

43. Why is a line heater required when using GMAW?
SMAW - GTAW
Dry ice can form within the flow control openings and cause blockage of shielding gas
The negative side of a welding unit
The Arc voltage

44. Why is a fiber washer required and what cylinder gas requires it?
Cause flaking - which can clog the liner and contact tube
If you dont know this check your phone
Constant current (CC)
To prevent leakage - Carbon Dioxide (CO2)

45. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Puddle fluidity
These terms are quite restrictive and often technically incorrect
If you dont know this check your phone

46. List the factors that determine the mode of metal transfer
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Constant- speed wire feeders and Voltage- sennsing wire feeders
Cause flaking - which can clog the liner and contact tube
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

47. Why must CO2 cylinders be used in the vertical position?
Puddle fluidity
Pressure vessels and the piping industry
To prevent drawing of liquid CO2 (Carbon Dioxide)
Minimum distortion due to low heat input

48. What 2 controls are found on a GMAW set- up?
The resistace to electrical current flow increases with it. Causing the electrode to heat
Pressure vessels and the piping industry
Controls the rate of flow of a shielding gas to the gun nozzle
Wire feed speed - Voltage control

49. With straight polarity where is 2/3 of the arc energy?
SMAW - GTAW
Guns
The negative side of a welding unit
1/4 inch to 1/2 inch

50. List 3 forms compressed gases may be supplied for welding
Generally not as accurate
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
If you dont know this check your phone
Wire feed speed - Voltage control