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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. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
National Electrical Manufactures Association
Cause flaking - which can clog the liner and contact tube
Minutes of elapsed time continually run (out of 10 minutes)
The resistace to electrical current flow increases with it. Causing the electrode to heat

2. What does inductance control?
Motor driven generators - Transformer rectifiers - and Inverter designs
SMAW - GTAW
The time rate of response for the current rise and fall
Penetration and burn - off rate of the electrode

3. What processes are constant current (CC) power sources designed to be used with?
SMAW - GTAW
Dry ice can form within the flow control openings and cause blockage of shielding gas
Gives arc voltage values to the control system of the feeder
12 to 22 arc volts

4. Give a description of 'pinch effect'
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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
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
3

5. What output on the welding machine is used to rate the duty cycle?
12 to 22 arc volts
Short- circuiting transfer - Globular transfer - Spray transfer
Motor driven generators - Transformer rectifiers - and Inverter designs
Minutes of elapsed time continually run (out of 10 minutes)

6. List 3 forms compressed gases may be supplied for welding
To prevent leakage - Carbon Dioxide (CO2)
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Welding process that joins metals by heating them with an electric arc
Guns

7. What does voltage do in an electrical circuit?
Voltage is the force that overcomes resistance to allow amperage flow
Duty cycle
85%
3

8. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
...
Spatter problems and poor weld appearance
DCEP (Direct Current Electrode Positive) Reverse Polarity
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

9. What does a flowmeter do and what does it measure?
Controls the rate of flow of a shielding gas to the gun nozzle
Pressure - The rate of flow of a shielding gas
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Reducing the gas source pressure to a constant working pressure

10. What effect does increasing and decreasing the inductance have on the weld?
5.8 to 12.5 L/min
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
Constant current (CC)

11. Why is the term GMAW preferred over MIG or MAG?
To limit the short circuiting current so that spatter is reduced
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Dry ice can form within the flow control openings and cause blockage of shielding gas
These terms are quite restrictive and often technically incorrect

12. What is the purpose of the shielding gas used in GMAW?
Shielding the molten weld metal from atmospheric contamination
Reducing the gas source pressure to a constant working pressure
Flux cored wires
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

13. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Minimum distortion due to low heat input
(DCEP) Direct Current Electrode Positive or Reverse polarity
AWS and CSA

14. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
SMAW - GTAW
12 to 22 arc volts
85%

15. What does the term GMAW identify?
National Electrical Manufactures Association
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Gas metal arc welding
V groove or U groove

16. Why is a line heater required when using GMAW?
These terms are quite restrictive and often technically incorrect
The Arc voltage
Aluminum wire
Dry ice can form within the flow control openings and cause blockage of shielding gas

17. What is a typical flow rate of CO2 for short circuit transfer?
V groove or U groove
Higher 26 to 35 arc volts
If you dont know this check your phone
5.8 to 12.5 L/min

18. What is another term for electrode holders for GMAW?
Constant- speed wire feeders and Voltage- sennsing wire feeders
The negative side of a welding unit
Guns
The time rate of response for the current rise and fall

19. What wire are knurled drive rolls most commonly used on?
3
Flux cored wires
The Arc voltage
DCEP (Direct Current Electrode Positive) Reverse Polarity

20. What power sources are used with the GMAW Process?
Wire feed speed - Voltage control
Motor driven generators - Transformer rectifiers - and Inverter designs
Minimum distortion due to low heat input
Constant current (CC)

21. Regulators control_____________ flowmeters SHOW____________.
Reducing the gas source pressure to a constant working pressure
Gas metal arc welding
Higher 26 to 35 arc volts
Pressure - The rate of flow of a shielding gas

22. Why must CO2 cylinders be used in the vertical position?
Minutes of elapsed time continually run (out of 10 minutes)
When the filler wire is in direct contract with the base metal
Insufficient current to melt the wire off cleanly
To prevent drawing of liquid CO2 (Carbon Dioxide)

23. What is the key advantage of short circuiting transfer?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Minimum distortion due to low heat input
85%

24. A pull type drive system is usually used on what type of material?
5.8 to 12.5 L/min
The Arc voltage
Insufficient current to melt the wire off cleanly
Aluminum wire

25. What is the preferred drive roll design for solid wires?
V groove or U groove
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
85%
Speed of the feed motor and - starting / stopping electrode feed

26. List 3 wire drive systems and give a short description of each
Cause flaking - which can clog the liner and contact tube
By there current carrying capacity
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
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

27. With straight polarity where is 2/3 of the arc energy?
To limit the short circuiting current so that spatter is reduced
Minimum distortion due to low heat input
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
The negative side of a welding unit

28. What controls amperage when using GMAW?
Wire feed speed
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
Penetration and burn - off rate of the electrode

29. Why is a fiber washer required and what cylinder gas requires it?
Speed of the feed motor and - starting / stopping electrode feed
Constant current (CC)
Flux cored wires
To prevent leakage - Carbon Dioxide (CO2)

30. What happens when the electrode extension is increased?
The resistace to electrical current flow increases with it. Causing the electrode to heat
Generally not as accurate
1/4 inch to 1/2 inch
The negative side of a welding unit

31. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
3
To limit the short circuiting current so that spatter is reduced
Motor driven generators - Transformer rectifiers - and Inverter designs
If you dont know this check your phone

32. Why is globular transfer generally avoided with GMAW?
To prevent drawing of liquid CO2 (Carbon Dioxide)
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Spatter problems and poor weld appearance
Duty cycle

33. What is the required arc voltage used for short circuit transfer?
The Arc voltage
(DCEP) Direct Current Electrode Positive or Reverse polarity
12 to 22 arc volts
DCEP (Direct Current Electrode Positive) Reverse Polarity

34. What would be an indication that the drive roll pressure is adjusted correctly?
Gives arc voltage values to the control system of the feeder
Minimum distortion due to low heat input
85%
Wire feeds smoothly (yet will slip should a problem occur in the gun)

35. What is the maximum distance that hard wire can be successfully pushed?
...
15 feet (4.5 meters)
The time rate of response for the current rise and fall
20 to 200 times per second

36. What type of power source is used with a constant speed wire feeder?
Reducing the gas source pressure to a constant working pressure
Penetration and burn - off rate of the electrode
Short- circuiting transfer - Globular transfer - Spray transfer
Constant voltage (CV)

37. List several industries that would use GMAW
Pressure vessels and the piping industry
To prevent drawing of liquid CO2 (Carbon Dioxide)
Constant voltage (CV)
12 to 22 arc volts

38. 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
To prevent leakage - Carbon Dioxide (CO2)
Constant- speed wire feeders and Voltage- sennsing wire feeders
Puddle fluidity

39. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Generally not as accurate
Gives arc voltage values to the control system of the feeder
Insufficient current to melt the wire off cleanly
SMAW - GTAW

40. What 2 controls are found on a GMAW set- up?
The resistace to electrical current flow increases with it. Causing the electrode to heat
Wire feed speed - Voltage control
If you dont know this check your phone
12 to 22 arc volts

41. How many times per second does short circuiting take place?
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Pressure vessels and the piping industry
3
20 to 200 times per second

42. What is the main purpose of 'slope'?
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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
To limit the short circuiting current so that spatter is reduced

43. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Spatter problems and poor weld appearance
Aluminum wire
Gives arc voltage values to the control system of the feeder
These terms are quite restrictive and often technically incorrect

44. What type of power source is commonly used with a voltage sensing wire feeder?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Gas metal arc welding
Constant current (CC)
By there current carrying capacity

45. What 2 organizations designate specifications for GMAW wires?
AWS and CSA
To prevent drawing of liquid CO2 (Carbon Dioxide)
Wire feed speed - Voltage control
Aluminum wire

46. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
85%
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Higher 26 to 35 arc volts

47. What is the recommended electrode stick- out for .035 solid wire?
Dry ice can form within the flow control openings and cause blockage of shielding gas
1/4 inch to 1/2 inch
Motor driven generators - Transformer rectifiers - and Inverter designs
Constant current (CC)

48. What does the wire feeder control?
The time rate of response for the current rise and fall
Speed of the feed motor and - starting / stopping electrode feed
These terms are quite restrictive and often technically incorrect
5.8 to 12.5 L/min

49. List the basic equipment requirements for the GMAW process
Pressure - The rate of flow of a shielding gas
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Constant voltage (CV)
Gas metal arc welding

50. What does the abbreviation NEMA stand for?
Reducing the gas source pressure to a constant working pressure
If you dont know this check your phone
National Electrical Manufactures Association
Shielding the molten weld metal from atmospheric contamination