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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 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
Higher 26 to 35 arc volts
12 to 22 arc volts
Minutes of elapsed time continually run (out of 10 minutes)

2. What happens when the electrode extension is increased?
Duty cycle
When the filler wire is in direct contract with the base metal
The resistace to electrical current flow increases with it. Causing the electrode to heat
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

3. What type of power source is commonly used with a voltage sensing wire feeder?
Constant current (CC)
20 to 200 times per second
Welding process that joins metals by heating them with an electric arc
The resistace to electrical current flow increases with it. Causing the electrode to heat

4. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
Insufficient current to melt the wire off cleanly
Gives arc voltage values to the control system of the feeder
Constant voltage (CV)
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5. List 3 wire drive systems and give a short description of each
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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
These terms are quite restrictive and often technically incorrect
85%

6. What controls amperage when using GMAW?
Higher 26 to 35 arc volts
Wire feed speed
Gas metal arc welding
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

7. Why must CO2 cylinders be used in the vertical position?
To prevent drawing of liquid CO2 (Carbon Dioxide)
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
Puddle fluidity

8. What type of power source is used with a constant speed wire feeder?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
To prevent drawing of liquid CO2 (Carbon Dioxide)
Constant voltage (CV)
Motor driven generators - Transformer rectifiers - and Inverter designs

9. What current and polarity is generally used with GMAW?
The resistace to electrical current flow increases with it. Causing the electrode to heat
DCEP (Direct Current Electrode Positive) Reverse Polarity
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

10. When is the metal transferred with short circuit transfer?
When the filler wire is in direct contract with the base metal
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
AWS and CSA
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

11. Why is globular transfer generally avoided with GMAW?
Spatter problems and poor weld appearance
Duty cycle
Guns
Constant voltage (CV)

12. List the three methods of metal transfer with GMAW
These terms are quite restrictive and often technically incorrect
Shielding the molten weld metal from atmospheric contamination
Penetration and burn - off rate of the electrode
Short- circuiting transfer - Globular transfer - Spray transfer

13. What is the main purpose of 'slope'?
To limit the short circuiting current so that spatter is reduced
Duty cycle
85%
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14. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
85%
When the filler wire is in direct contract with the base metal
Wire feed speed - Voltage control

15. What is the effect of too much slope?
Controls the rate of flow of a shielding gas to the gun nozzle
The Arc voltage
Insufficient current to melt the wire off cleanly
Flux cored wires

16. List the basic equipment requirements for the GMAW process
Penetration and burn - off rate of the electrode
The time rate of response for the current rise and fall
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Spatter problems and poor weld appearance

17. In the GMAW process what does amperage control?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Controls the rate of flow of a shielding gas to the gun nozzle
DCEP (Direct Current Electrode Positive) Reverse Polarity
Penetration and burn - off rate of the electrode

18. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Puddle fluidity
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Wire feed speed
Cause flaking - which can clog the liner and contact tube

19. A 10 minute cycle of welding time vs cooling time a given machine can handle.
5.8 to 12.5 L/min
(DCEP) Direct Current Electrode Positive or Reverse polarity
Duty cycle
3

20. What is the required arc voltage used for short circuit transfer?
Cause flaking - which can clog the liner and contact tube
DCEP (Direct Current Electrode Positive) Reverse Polarity
12 to 22 arc volts
Wire feeds smoothly (yet will slip should a problem occur in the gun)

21. What does a flowmeter do and what does it measure?
Constant- speed wire feeders and Voltage- sennsing wire feeders
Reducing the gas source pressure to a constant working pressure
Dry ice can form within the flow control openings and cause blockage of shielding gas
Controls the rate of flow of a shielding gas to the gun nozzle

22. What is a solenoid valve and what actuates it?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
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
Motor driven generators - Transformer rectifiers - and Inverter designs

23. What wire are knurled drive rolls most commonly used on?
Penetration and burn - off rate of the electrode
Flux cored wires
National Electrical Manufactures Association
Speed of the feed motor and - starting / stopping electrode feed

24. What 2 controls are found on a GMAW set- up?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Spatter problems and poor weld appearance
...
Wire feed speed - Voltage control

25. In the GMAW process what does voltage control?
Puddle fluidity
Generally not as accurate
AWS and CSA
15 feet (4.5 meters)

26. With straight polarity where is 2/3 of the arc energy?
5.8 to 12.5 L/min
The negative side of a welding unit
Generally not as accurate
Higher 26 to 35 arc volts

27. What is the purpose of a regulator and what does it indicate on its gauges?
Reducing the gas source pressure to a constant working pressure
DCEP (Direct Current Electrode Positive) Reverse Polarity
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
The negative side of a welding unit

28. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
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
National Electrical Manufactures Association
Cause flaking - which can clog the liner and contact tube

29. What power sources are used with the GMAW Process?
Motor driven generators - Transformer rectifiers - and Inverter designs
Aluminum wire
Duty cycle
Pressure - The rate of flow of a shielding gas

30. What are the 2 types of wire feeders available?
Dry ice can form within the flow control openings and cause blockage of shielding gas
15 feet (4.5 meters)
These terms are quite restrictive and often technically incorrect
Constant- speed wire feeders and Voltage- sennsing wire feeders

31. 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
Shielding the molten weld metal from atmospheric contamination
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
The time rate of response for the current rise and fall

32. Draw a typical volt amp curve for a machine that is designed for GMAW
Generally not as accurate
Constant current (CC)
If you dont know this check your phone
SMAW - GTAW

33. What is the key advantage of short circuiting transfer?
These terms are quite restrictive and often technically incorrect
Motor driven generators - Transformer rectifiers - and Inverter designs
Minimum distortion due to low heat input
Pressure - The rate of flow of a shielding gas

34. What does inductance control?
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
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

35. List several industries that would use GMAW
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Pressure - The rate of flow of a shielding gas
20 to 200 times per second
Pressure vessels and the piping industry

36. What output on the welding machine is used to rate the duty cycle?
Controls the rate of flow of a shielding gas to the gun nozzle
When the filler wire is in direct contract with the base metal
Minutes of elapsed time continually run (out of 10 minutes)
Reducing the gas source pressure to a constant working pressure

37. Why is a fiber washer required and what cylinder gas requires it?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Constant voltage (CV)
To prevent leakage - Carbon Dioxide (CO2)
SMAW - GTAW

38. List 3 forms compressed gases may be supplied for welding
Constant- speed wire feeders and Voltage- sennsing wire feeders
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Wire feeds smoothly (yet will slip should a problem occur in the gun)
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

39. Why is a line heater required when using GMAW?
The resistace to electrical current flow increases with it. Causing the electrode to heat
Cause flaking - which can clog the liner and contact tube
Dry ice can form within the flow control openings and cause blockage of shielding gas
Pressure - The rate of flow of a shielding gas

40. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Shielding the molten weld metal from atmospheric contamination
Generally not as accurate
DCEP (Direct Current Electrode Positive) Reverse Polarity
Wire feeds smoothly (yet will slip should a problem occur in the gun)

41. What would be an indication that the drive roll pressure is adjusted correctly?
Voltage is the force that overcomes resistance to allow amperage flow
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Constant current (CC)
20 to 200 times per second

42. What is the preferred drive roll design for solid wires?
The negative side of a welding unit
If you dont know this check your phone
Minimum distortion due to low heat input
V groove or U groove

43. What does the wire feeder control?
National Electrical Manufactures Association
1/4 inch to 1/2 inch
Wire feed speed - Voltage control
Speed of the feed motor and - starting / stopping electrode feed

44. What is an advantage of pulsed arc transfer with GMAW?
V groove or U groove
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
Minutes of elapsed time continually run (out of 10 minutes)

45. Give a brief description of the GMAW process
Gives arc voltage values to the control system of the feeder
Welding process that joins metals by heating them with an electric arc
...
Wire feed speed - Voltage control

46. What is the maximum distance that hard wire can be successfully pushed?
V groove or U groove
The resistace to electrical current flow increases with it. Causing the electrode to heat
15 feet (4.5 meters)
Duty cycle

47. What does the term GMAW identify?
Higher 26 to 35 arc volts
Gas metal arc welding
Cause flaking - which can clog the liner and contact tube
Shielding the molten weld metal from atmospheric contamination

48. Why is the term GMAW preferred over MIG or MAG?
These terms are quite restrictive and often technically incorrect
V groove or U groove
Voltage is the force that overcomes resistance to allow amperage flow
When the filler wire is in direct contract with the base metal

49. 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
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Insufficient current to melt the wire off cleanly
If you dont know this check your phone

50. What is another term for electrode holders for GMAW?
Guns
The negative side of a welding unit
Higher 26 to 35 arc volts
Spatter problems and poor weld appearance