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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.
Don't refresh. All questions and answers are randomly picked and ordered every time you load a test.

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 voltage do in an electrical circuit?
National Electrical Manufactures Association
Motor driven generators - Transformer rectifiers - and Inverter designs
Voltage is the force that overcomes resistance to allow amperage flow
3

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

3. When is the metal transferred with short circuit transfer?
Dry ice can form within the flow control openings and cause blockage of shielding gas
12 to 22 arc volts
When the filler wire is in direct contract with the base metal
15 feet (4.5 meters)

4. Give a description of 'pinch effect'
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Short- circuiting transfer - Globular transfer - Spray transfer
V groove or U groove
15 feet (4.5 meters)

5. What are the 2 types of wire feeders available?
Constant- speed wire feeders and Voltage- sennsing wire feeders
Short- circuiting transfer - Globular transfer - Spray transfer
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)

6. 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
Constant- speed wire feeders and Voltage- sennsing wire feeders
Constant voltage (CV)
Wire feed speed

7. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
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By there current carrying capacity
SMAW - GTAW
Minutes of elapsed time continually run (out of 10 minutes)

8. What processes are constant current (CC) power sources designed to be used with?
The Arc voltage
SMAW - GTAW
To prevent drawing of liquid CO2 (Carbon Dioxide)
DCEP (Direct Current Electrode Positive) Reverse Polarity

9. What does the wire feeder control?
V groove or U groove
Dry ice can form within the flow control openings and cause blockage of shielding gas
Puddle fluidity
Speed of the feed motor and - starting / stopping electrode feed

10. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
(DCEP) Direct Current Electrode Positive or Reverse polarity
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
Generally not as accurate
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11. In the GMAW process what does voltage control?
Duty cycle
Generally not as accurate
V groove or U groove
Puddle fluidity

12. What does the abbreviation NEMA stand for?
AWS and CSA
These terms are quite restrictive and often technically incorrect
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
National Electrical Manufactures Association

13. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Generally not as accurate
Insufficient current to melt the wire off cleanly
AWS and CSA
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14. List several industries that would use GMAW
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
To limit the short circuiting current so that spatter is reduced
Pressure vessels and the piping industry
Speed of the feed motor and - starting / stopping electrode feed

15. Draw a typical volt amp curve for a machine that is designed for GMAW
AWS and CSA
Short- circuiting transfer - Globular transfer - Spray transfer
Guns
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16. What is the purpose of the shielding gas used in GMAW?
Constant current (CC)
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Shielding the molten weld metal from atmospheric contamination
Reducing the gas source pressure to a constant working pressure

17. What type of power source is commonly used with a voltage sensing wire feeder?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Reducing the gas source pressure to a constant working pressure
Spatter problems and poor weld appearance
Constant current (CC)

18. What wire are knurled drive rolls most commonly used on?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Flux cored wires
Motor driven generators - Transformer rectifiers - and Inverter designs

19. What is another term for electrode holders for GMAW?
These terms are quite restrictive and often technically incorrect
The time rate of response for the current rise and fall
Pressure vessels and the piping industry
Guns

20. List 3 forms compressed gases may be supplied for welding
Constant current (CC)
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Flux cored wires
Reducing the gas source pressure to a constant working pressure

21. What controls the wire speed on a voltage sensing wire feeder?
(DCEP) Direct Current Electrode Positive or Reverse polarity
Constant- speed wire feeders and Voltage- sennsing wire feeders
The Arc voltage
Aluminum wire

22. List the three methods of metal transfer with GMAW
Motor driven generators - Transformer rectifiers - and Inverter designs
Short- circuiting transfer - Globular transfer - Spray transfer
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Puddle fluidity

23. What is the key advantage of short circuiting transfer?
Constant- speed wire feeders and Voltage- sennsing wire feeders
Constant current (CC)
Minimum distortion due to low heat input
When the filler wire is in direct contract with the base metal

24. A 10 minute cycle of welding time vs cooling time a given machine can handle.
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
Voltage is the force that overcomes resistance to allow amperage flow
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Duty cycle

25. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
3
Penetration and burn - off rate of the electrode
Pressure - The rate of flow of a shielding gas
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

26. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
These terms are quite restrictive and often technically incorrect
Pressure vessels and the piping industry
...
When the filler wire is in direct contract with the base metal

27. List the basic equipment requirements for the GMAW process
15 feet (4.5 meters)
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
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

28. What is the preferred drive roll design for solid wires?
V groove or U groove
Controls the rate of flow of a shielding gas to the gun nozzle
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Short- circuiting transfer - Globular transfer - Spray transfer

29. Why is a fiber washer required and what cylinder gas requires it?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
12 to 22 arc volts
...
To prevent leakage - Carbon Dioxide (CO2)

30. What power sources are used with the GMAW Process?
(DCEP) Direct Current Electrode Positive or Reverse polarity
Wire feed speed - Voltage control
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Motor driven generators - Transformer rectifiers - and Inverter designs

31. What controls amperage when using GMAW?
12 to 22 arc volts
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
To limit the short circuiting current so that spatter is reduced
Wire feed speed

32. Why must CO2 cylinders be used in the vertical position?
Aluminum wire
The time rate of response for the current rise and fall
If you dont know this check your phone
To prevent drawing of liquid CO2 (Carbon Dioxide)

33. Why is globular transfer generally avoided with GMAW?
Constant current (CC)
By there current carrying capacity
V groove or U groove
Spatter problems and poor weld appearance

34. What happens when the electrode extension is increased?
The resistace to electrical current flow increases with it. Causing the electrode to heat
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Constant current (CC)
Speed of the feed motor and - starting / stopping electrode feed

35. What does a flowmeter do and what does it measure?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Controls the rate of flow of a shielding gas to the gun nozzle
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Aluminum wire

36. What current and polarity is generally used with GMAW?
DCEP (Direct Current Electrode Positive) Reverse Polarity
The Arc voltage
Wire feed speed - Voltage control
If you dont know this check your phone

37. 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
Generally not as accurate
Minimum distortion due to low heat input
V groove or U groove

38. What type of power source is used with a constant speed wire feeder?
(DCEP) Direct Current Electrode Positive or Reverse polarity
Dry ice can form within the flow control openings and cause blockage of shielding gas
Gas metal arc welding
Constant voltage (CV)

39. How many times per second does short circuiting take place?
Insufficient current to melt the wire off cleanly
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
20 to 200 times per second
Spatter problems and poor weld appearance

40. What is the main purpose of 'slope'?
Constant voltage (CV)
The negative side of a welding unit
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
To limit the short circuiting current so that spatter is reduced

41. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Constant- speed wire feeders and Voltage- sennsing wire feeders
1/4 inch to 1/2 inch
15 feet (4.5 meters)
Higher 26 to 35 arc volts

42. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Reducing the gas source pressure to a constant working pressure
20 to 200 times per second
Gives arc voltage values to the control system of the feeder
Spatter problems and poor weld appearance

43. What would be an indication that the drive roll pressure is adjusted correctly?
SMAW - GTAW
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Cause flaking - which can clog the liner and contact tube
Generally not as accurate

44. Why is the term GMAW preferred over MIG or MAG?
By there current carrying capacity
Pressure - The rate of flow of a shielding gas
These terms are quite restrictive and often technically incorrect
Gas metal arc welding

45. What is the maximum distance that hard wire can be successfully pushed?
Insufficient current to melt the wire off cleanly
15 feet (4.5 meters)
Speed of the feed motor and - starting / stopping electrode feed
The resistace to electrical current flow increases with it. Causing the electrode to heat

46. What is the effect of too much slope?
Insufficient current to melt the wire off cleanly
The resistace to electrical current flow increases with it. Causing the electrode to heat
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
By there current carrying capacity

47. List the factors that determine the mode of metal transfer
National Electrical Manufactures Association
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Pressure - The rate of flow of a shielding gas
SMAW - GTAW

48. What effect does increasing and decreasing the inductance have on the weld?
Constant current (CC)
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Flux cored wires
Reducing the gas source pressure to a constant working pressure

49. What is the required arc voltage used for short circuit transfer?
The negative side of a welding unit
12 to 22 arc volts
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Guns

50. What does inductance control?
Pressure - The rate of flow of a shielding gas
Welding process that joins metals by heating them with an electric arc
The time rate of response for the current rise and fall
85%