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

2. What is the purpose of the shielding gas used in GMAW?
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)
85%
Shielding the molten weld metal from atmospheric contamination

3. What power sources are used with the GMAW Process?
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)
85%
Motor driven generators - Transformer rectifiers - and Inverter designs

4. What does voltage do in an electrical circuit?
Voltage is the force that overcomes resistance to allow amperage flow
Minimum distortion due to low heat input
12 to 22 arc volts
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5. Draw a typical volt amp curve for a machine that is designed for GMAW
Spatter problems and poor weld appearance
Wire feed speed - Voltage control
85%
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6. Give a description of 'pinch effect'
Higher 26 to 35 arc volts
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
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

7. What is the key advantage of short circuiting transfer?
The negative side of a welding unit
Cause flaking - which can clog the liner and contact tube
5.8 to 12.5 L/min
Minimum distortion due to low heat input

8. What is the required arc voltage used for short circuit transfer?
Guns
12 to 22 arc volts
15 feet (4.5 meters)
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9. List several industries that would use GMAW
Minimum distortion due to low heat input
Pressure vessels and the piping industry
Short- circuiting transfer - Globular transfer - Spray transfer
Puddle fluidity

10. What is an advantage of pulsed arc transfer with GMAW?
Constant- speed wire feeders and Voltage- sennsing wire feeders
3
Puddle fluidity
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

11. What does the abbreviation NEMA stand for?
85%
15 feet (4.5 meters)
National Electrical Manufactures Association
To prevent drawing of liquid CO2 (Carbon Dioxide)

12. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Higher 26 to 35 arc volts
15 feet (4.5 meters)
The negative side of a welding unit
...

13. Why must CO2 cylinders be used in the vertical position?
By there current carrying capacity
To prevent drawing of liquid CO2 (Carbon Dioxide)
20 to 200 times per second
The negative side of a welding unit

14. What is another term for electrode holders for GMAW?
Guns
The Arc voltage
To prevent drawing of liquid CO2 (Carbon Dioxide)
Insufficient current to melt the wire off cleanly

15. What does the wire feeder control?
Constant current (CC)
Guns
(DCEP) Direct Current Electrode Positive or Reverse polarity
Speed of the feed motor and - starting / stopping electrode feed

16. A pull type drive system is usually used on what type of material?
3
Wire feed speed - Voltage control
85%
Aluminum wire

17. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
Wire feeds smoothly (yet will slip should a problem occur in the gun)
3
Constant current (CC)
Insufficient current to melt the wire off cleanly

18. In the GMAW process what does amperage control?
To prevent leakage - Carbon Dioxide (CO2)
Penetration and burn - off rate of the electrode
Reducing the gas source pressure to a constant working pressure
These terms are quite restrictive and often technically incorrect

19. List the basic equipment requirements for the GMAW process
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Insufficient current to melt the wire off cleanly
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Higher 26 to 35 arc volts

20. How many times per second does short circuiting take place?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Gives arc voltage values to the control system of the feeder
Cause flaking - which can clog the liner and contact tube
20 to 200 times per second

21. Why is a fiber washer required and what cylinder gas requires it?
The time rate of response for the current rise and fall
Constant voltage (CV)
To prevent leakage - Carbon Dioxide (CO2)
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

22. Why is globular transfer generally avoided with GMAW?
Spatter problems and poor weld appearance
Constant current (CC)
Wire feed speed
Dry ice can form within the flow control openings and cause blockage of shielding gas

23. With straight polarity where is 2/3 of the arc energy?
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3
The negative side of a welding unit
Dry ice can form within the flow control openings and cause blockage of shielding gas

24. List the factors that determine the mode of metal transfer
Guns
V groove or U groove
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
1/4 inch to 1/2 inch

25. What happens when the electrode extension is increased?
Constant current (CC)
Wire feed speed
Gas metal arc welding
The resistace to electrical current flow increases with it. Causing the electrode to heat

26. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
1/4 inch to 1/2 inch
When the filler wire is in direct contract with the base metal
Cause flaking - which can clog the liner and contact tube
National Electrical Manufactures Association

27. List 3 wire drive systems and give a short description of each
Speed of the feed motor and - starting / stopping electrode feed
(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
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

28. What wire are knurled drive rolls most commonly used on?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Gives arc voltage values to the control system of the feeder
The negative side of a welding unit
Flux cored wires

29. What type of power source is commonly used with a voltage sensing wire feeder?
Motor driven generators - Transformer rectifiers - and Inverter designs
Controls the rate of flow of a shielding gas to the gun nozzle
Constant current (CC)
To limit the short circuiting current so that spatter is reduced

30. What 2 organizations designate specifications for GMAW wires?
Spatter problems and poor weld appearance
Minutes of elapsed time continually run (out of 10 minutes)
AWS and CSA
Pressure - The rate of flow of a shielding gas

31. What processes are constant current (CC) power sources designed to be used with?
Constant current (CC)
Dry ice can form within the flow control openings and cause blockage of shielding gas
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
SMAW - GTAW

32. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
Wire feed speed
Welding process that joins metals by heating them with an electric arc
Generally not as accurate
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33. What is the maximum distance that hard wire can be successfully pushed?
Cause flaking - which can clog the liner and contact tube
These terms are quite restrictive and often technically incorrect
DCEP (Direct Current Electrode Positive) Reverse Polarity
15 feet (4.5 meters)

34. What is a typical flow rate of CO2 for short circuit transfer?
5.8 to 12.5 L/min
Voltage is the force that overcomes resistance to allow amperage flow
Controls the rate of flow of a shielding gas to the gun nozzle
The time rate of response for the current rise and fall

35. When is the metal transferred with short circuit transfer?
12 to 22 arc volts
Penetration and burn - off rate of the electrode
Insufficient current to melt the wire off cleanly
When the filler wire is in direct contract with the base metal

36. List 3 forms compressed gases may be supplied for welding
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
To prevent drawing of liquid CO2 (Carbon Dioxide)
National Electrical Manufactures Association
The negative side of a welding unit

37. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Guns
Duty cycle
Shielding the molten weld metal from atmospheric contamination
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38. What is the disadvantage of the gauge preset type of regulator/flowmeter?
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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
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Generally not as accurate

39. Why is the term GMAW preferred over MIG or MAG?
Constant current (CC)
These terms are quite restrictive and often technically incorrect
1/4 inch to 1/2 inch
Reducing the gas source pressure to a constant working pressure

40. List the three methods of metal transfer with GMAW
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Short- circuiting transfer - Globular transfer - Spray transfer
Reducing the gas source pressure to a constant working pressure

41. What controls amperage when using GMAW?
Dry ice can form within the flow control openings and cause blockage of shielding gas
Wire feed speed
If you dont know this check your phone
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

42. What is a solenoid valve and what actuates it?
Pressure - The rate of flow of a shielding gas
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
The negative side of a welding unit
Wire feed speed - Voltage control

43. What controls the wire speed on a voltage sensing wire feeder?
The Arc voltage
The negative side of a welding unit
Wire feed speed
Welding process that joins metals by heating them with an electric arc

44. What output on the welding machine is used to rate the duty cycle?
Dry ice can form within the flow control openings and cause blockage of shielding gas
5.8 to 12.5 L/min
The time rate of response for the current rise and fall
Minutes of elapsed time continually run (out of 10 minutes)

45. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
Constant- speed wire feeders and Voltage- sennsing wire feeders
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
85%

46. What is the purpose of a regulator and what does it indicate on its gauges?
Voltage is the force that overcomes resistance to allow amperage flow
Flux cored wires
Reducing the gas source pressure to a constant working pressure
Pressure vessels and the piping industry

47. What does inductance control?
The time rate of response for the current rise and fall
20 to 200 times per second
Controls the rate of flow of a shielding gas to the gun nozzle
The Arc voltage

48. What 2 controls are found on a GMAW set- up?
V groove or U groove
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Wire feed speed - Voltage control
15 feet (4.5 meters)

49. Regulators control_____________ flowmeters SHOW____________.
Gives arc voltage values to the control system of the feeder
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Cause flaking - which can clog the liner and contact tube
Pressure - The rate of flow of a shielding gas

50. What does the term GMAW identify?
Short- circuiting transfer - Globular transfer - Spray transfer
Gas metal arc welding
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
(DCEP) Direct Current Electrode Positive or Reverse polarity