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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. Why must CO2 cylinders be used in the vertical position?
Insufficient current to melt the wire off cleanly
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 drawing of liquid CO2 (Carbon Dioxide)
Welding process that joins metals by heating them with an electric arc

2. What is another term for electrode holders for GMAW?
5.8 to 12.5 L/min
Reducing the gas source pressure to a constant working pressure
Gives arc voltage values to the control system of the feeder
Guns

3. Why is globular transfer generally avoided with GMAW?
Welding process that joins metals by heating them with an electric arc
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
20 to 200 times per second
Spatter problems and poor weld appearance

4. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
(DCEP) Direct Current Electrode Positive or Reverse polarity
Short- circuiting transfer - Globular transfer - Spray transfer
...
Voltage is the force that overcomes resistance to allow amperage flow

5. What is a typical flow rate of CO2 for short circuit transfer?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Higher 26 to 35 arc volts
Puddle fluidity
5.8 to 12.5 L/min

6. List the three methods of metal transfer with GMAW
The resistace to electrical current flow increases with it. Causing the electrode to heat
Short- circuiting transfer - Globular transfer - Spray transfer
Wire feed speed
V groove or U groove

7. What wire are knurled drive rolls most commonly used on?
...
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Flux cored wires
Reducing the gas source pressure to a constant working pressure

8. What is a solenoid valve and what actuates it?
Shielding the molten weld metal from atmospheric contamination
Gives arc voltage values to the control system of the feeder
20 to 200 times per second
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

9. List the basic equipment requirements for the GMAW process
By there current carrying capacity
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
DCEP (Direct Current Electrode Positive) Reverse Polarity
V groove or U groove

10. What power sources are used with the GMAW Process?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Short- circuiting transfer - Globular transfer - Spray transfer
Motor driven generators - Transformer rectifiers - and Inverter designs
Insufficient current to melt the wire off cleanly

11. How many times per second does short circuiting take place?
1/4 inch to 1/2 inch
Constant voltage (CV)
Insufficient current to melt the wire off cleanly
20 to 200 times per second

12. List several industries that would use GMAW
Wire feeds smoothly (yet will slip should a problem occur in the gun)
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
Reducing the gas source pressure to a constant working pressure

13. What is the preferred drive roll design for solid wires?
To prevent leakage - Carbon Dioxide (CO2)
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V groove or U groove

14. What is the required arc voltage used for short circuit transfer?
...
Voltage is the force that overcomes resistance to allow amperage flow
Duty cycle
12 to 22 arc volts

15. What controls the wire speed on a voltage sensing wire feeder?
The Arc voltage
Flux cored wires
15 feet (4.5 meters)
Speed of the feed motor and - starting / stopping electrode feed

16. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
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To limit the short circuiting current so that spatter is reduced
Pressure vessels and the piping industry
SMAW - GTAW

17. Why is a fiber washer required and what cylinder gas requires it?
Minimum distortion due to low heat input
Aluminum wire
To prevent leakage - Carbon Dioxide (CO2)
Welding process that joins metals by heating them with an electric arc

18. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Constant- speed wire feeders and Voltage- sennsing wire feeders
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Generally not as accurate
SMAW - GTAW

19. What is the effect of too much slope?
Controls the rate of flow of a shielding gas to the gun nozzle
Duty cycle
V groove or U groove
Insufficient current to melt the wire off cleanly

20. What does the wire feeder control?
National Electrical Manufactures Association
To limit the short circuiting current so that spatter is reduced
Speed of the feed motor and - starting / stopping electrode feed
1/4 inch to 1/2 inch

21. Why is a line heater required when using GMAW?
Constant current (CC)
Dry ice can form within the flow control openings and cause blockage of shielding gas
The Arc voltage
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

22. What is an advantage of pulsed arc transfer with GMAW?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Controls the rate of flow of a shielding gas to the gun nozzle
...
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

23. What would be an indication that the drive roll pressure is adjusted correctly?
Controls the rate of flow of a shielding gas to the gun nozzle
5.8 to 12.5 L/min
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

24. What does the abbreviation NEMA stand for?
By there current carrying capacity
National Electrical Manufactures Association
To prevent drawing of liquid CO2 (Carbon Dioxide)
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

25. What does the term GMAW identify?
Voltage is the force that overcomes resistance to allow amperage flow
Welding process that joins metals by heating them with an electric arc
Gas metal arc welding
To limit the short circuiting current so that spatter is reduced

26. List the factors that determine the mode of metal transfer
The Arc voltage
When the filler wire is in direct contract with the base metal
Wire feed speed - Voltage control
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

27. Regulators control_____________ flowmeters SHOW____________.
Wire feed speed
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Duty cycle
Pressure - The rate of flow of a shielding gas

28. What does a flowmeter do and what does it measure?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Controls the rate of flow of a shielding gas to the gun nozzle
V groove or U groove
Higher 26 to 35 arc volts

29. Give a brief description of the GMAW process
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Welding process that joins metals by heating them with an electric arc
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Higher 26 to 35 arc volts

30. What 2 organizations designate specifications for GMAW wires?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
AWS and CSA
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

31. A pull type drive system is usually used on what type of material?
5.8 to 12.5 L/min
Wire feed speed
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Aluminum wire

32. What is the maximum distance that hard wire can be successfully pushed?
15 feet (4.5 meters)
20 to 200 times per second
Guns
Duty cycle

33. 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
Constant- speed wire feeders and Voltage- sennsing wire feeders
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
To prevent leakage - Carbon Dioxide (CO2)

34. Why is the term GMAW preferred over MIG or MAG?
Pressure - The rate of flow of a shielding gas
These terms are quite restrictive and often technically incorrect
Minimum distortion due to low heat input
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

35. In the GMAW process what does amperage control?
Penetration and burn - off rate of the electrode
Gas metal arc welding
Speed of the feed motor and - starting / stopping electrode feed
Shielding the molten weld metal from atmospheric contamination

36. What is the key advantage of short circuiting transfer?
85%
To limit the short circuiting current so that spatter is reduced
Minimum distortion due to low heat input
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37. What effect does increasing and decreasing the inductance have on the weld?
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Wire feed speed
Penetration and burn - off rate of the electrode
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

38. What is the recommended electrode stick- out for .035 solid wire?
1/4 inch to 1/2 inch
Generally not as accurate
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
To prevent drawing of liquid CO2 (Carbon Dioxide)

39. What output on the welding machine is used to rate the duty cycle?
3
Welding process that joins metals by heating them with an electric arc
20 to 200 times per second
Minutes of elapsed time continually run (out of 10 minutes)

40. What is the purpose of the shielding gas used in GMAW?
Shielding the molten weld metal from atmospheric contamination
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
5.8 to 12.5 L/min
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

41. What current and polarity is generally used with GMAW?
12 to 22 arc volts
DCEP (Direct Current Electrode Positive) Reverse Polarity
20 to 200 times per second
These terms are quite restrictive and often technically incorrect

42. What controls amperage when using GMAW?
Insufficient current to melt the wire off cleanly
85%
Wire feed speed
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

43. In the GMAW process what does voltage control?
Puddle fluidity
DCEP (Direct Current Electrode Positive) Reverse Polarity
Voltage is the force that overcomes resistance to allow amperage flow
SMAW - GTAW

44. What is the main purpose of 'slope'?
85%
Minutes of elapsed time continually run (out of 10 minutes)
Wire feeds smoothly (yet will slip should a problem occur in the gun)
To limit the short circuiting current so that spatter is reduced

45. List 3 wire drive systems and give a short description of each
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Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Minimum distortion due to low heat input
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

46. What 2 controls are found on a GMAW set- up?
Wire feed speed - Voltage control
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
To prevent drawing of liquid CO2 (Carbon Dioxide)

47. With straight polarity where is 2/3 of the arc energy?
3
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
The negative side of a welding unit
Wire feeds smoothly (yet will slip should a problem occur in the gun)

48. What does inductance control?
15 feet (4.5 meters)
V groove or U groove
The time rate of response for the current rise and fall
Speed of the feed motor and - starting / stopping electrode feed

49. List 3 forms compressed gases may be supplied for welding
Shielding the molten weld metal from atmospheric contamination
When the filler wire is in direct contract with the base metal
Constant- speed wire feeders and Voltage- sennsing wire feeders
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

50. What happens when the electrode extension is increased?
Guns
The resistace to electrical current flow increases with it. Causing the electrode to heat
1/4 inch to 1/2 inch
Motor driven generators - Transformer rectifiers - and Inverter designs