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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. Give a description of 'pinch effect'
The Arc voltage
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Wire feeds smoothly (yet will slip should a problem occur in the gun)
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

2. What is an advantage of pulsed arc transfer with GMAW?
Gives arc voltage values to the control system of the feeder
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
National Electrical Manufactures Association
Puddle fluidity

3. What 2 organizations designate specifications for GMAW wires?
AWS and CSA
1/4 inch to 1/2 inch
Insufficient current to melt the wire off cleanly
Flux cored wires

4. What is the main purpose of 'slope'?
Gives arc voltage values to the control system of the feeder
To limit the short circuiting current so that spatter is reduced
Motor driven generators - Transformer rectifiers - and Inverter designs
Constant voltage (CV)

5. What happens when the electrode extension is increased?
By there current carrying capacity
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
The resistace to electrical current flow increases with it. Causing the electrode to heat

6. What processes are constant current (CC) power sources designed to be used with?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
The resistace to electrical current flow increases with it. Causing the electrode to heat
Spatter problems and poor weld appearance
SMAW - GTAW

7. Why is a fiber washer required and what cylinder gas requires it?
Higher 26 to 35 arc volts
Shielding the molten weld metal from atmospheric contamination
To prevent leakage - Carbon Dioxide (CO2)
Welding process that joins metals by heating them with an electric arc

8. What is the key advantage of short circuiting transfer?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Minimum distortion due to low heat input
To prevent leakage - Carbon Dioxide (CO2)

9. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
These terms are quite restrictive and often technically incorrect
When the filler wire is in direct contract with the base metal
Gives arc voltage values to the control system of the feeder
Voltage is the force that overcomes resistance to allow amperage flow

10. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
When the filler wire is in direct contract with the base metal
To limit the short circuiting current so that spatter is reduced
...
V groove or U groove

11. How many times per second does short circuiting take place?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
To limit the short circuiting current so that spatter is reduced
20 to 200 times per second
By there current carrying capacity

12. What is the preferred drive roll design for solid wires?
Generally not as accurate
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
V groove or U groove
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

13. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
AWS and CSA
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
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Higher 26 to 35 arc volts

14. With straight polarity where is 2/3 of the arc energy?
Short- circuiting transfer - Globular transfer - Spray transfer
Cause flaking - which can clog the liner and contact tube
Gas metal arc welding
The negative side of a welding unit

15. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Pressure vessels and the piping industry
Cause flaking - which can clog the liner and contact tube
To prevent leakage - Carbon Dioxide (CO2)
The time rate of response for the current rise and fall

16. What is a solenoid valve and what actuates it?
Constant voltage (CV)
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
85%
By there current carrying capacity

17. List the three methods of metal transfer with 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
Short- circuiting transfer - Globular transfer - Spray transfer
(DCEP) Direct Current Electrode Positive or Reverse polarity
DCEP (Direct Current Electrode Positive) Reverse Polarity

18. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Constant- speed wire feeders and Voltage- sennsing wire feeders
Duty cycle
Motor driven generators - Transformer rectifiers - and Inverter designs
Guns

19. Why is the term GMAW preferred over MIG or MAG?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
These terms are quite restrictive and often technically incorrect
Pressure - The rate of flow of a shielding gas
The negative side of a welding unit

20. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
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Gas metal arc welding
Generally not as accurate

21. What is the effect of too much slope?
3
(DCEP) Direct Current Electrode Positive or Reverse polarity
Insufficient current to melt the wire off cleanly
Short- circuiting transfer - Globular transfer - Spray transfer

22. 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
Guns
Welding process that joins metals by heating them with an electric arc
Controls the rate of flow of a shielding gas to the gun nozzle

23. List the factors that determine the mode of metal transfer
Speed of the feed motor and - starting / stopping electrode feed
...
Welding process that joins metals by heating them with an electric arc
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

24. What does the term GMAW identify?
Gas metal arc welding
Minutes of elapsed time continually run (out of 10 minutes)
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

25. What is a typical flow rate of CO2 for short circuit transfer?
5.8 to 12.5 L/min
Speed of the feed motor and - starting / stopping electrode feed
Flux cored wires
DCEP (Direct Current Electrode Positive) Reverse Polarity

26. What 2 controls are found on a GMAW set- up?
12 to 22 arc volts
Wire feed speed - Voltage control
Pressure vessels and the piping industry
Short- circuiting transfer - Globular transfer - Spray transfer

27. List several industries that would use GMAW
...
Motor driven generators - Transformer rectifiers - and Inverter designs
Pressure vessels and the piping industry
85%

28. In the GMAW process what does amperage control?
Penetration and burn - off rate of the electrode
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Flux cored wires
Generally not as accurate

29. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
85%
Short- circuiting transfer - Globular transfer - Spray transfer
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
20 to 200 times per second

30. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Higher 26 to 35 arc volts
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
The negative side of a welding unit
Pressure - The rate of flow of a shielding gas

31. Regulators control_____________ flowmeters SHOW____________.
Voltage is the force that overcomes resistance to allow amperage flow
(DCEP) Direct Current Electrode Positive or Reverse polarity
Aluminum wire
Pressure - The rate of flow of a shielding gas

32. List 3 forms compressed gases may be supplied for welding
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To limit the short circuiting current so that spatter is reduced
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Shielding the molten weld metal from atmospheric contamination

33. In the GMAW process what does voltage control?
Puddle fluidity
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Minimum distortion due to low heat input
SMAW - GTAW

34. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
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
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3

35. How are GMAW guns rated?
15 feet (4.5 meters)
By there current carrying capacity
Welding process that joins metals by heating them with an electric arc
85%

36. List the basic equipment requirements for the GMAW process
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
By there current carrying capacity
Voltage is the force that overcomes resistance to allow amperage flow

37. When is the metal transferred with short circuit transfer?
When the filler wire is in direct contract with the base metal
SMAW - GTAW
Flux cored wires
15 feet (4.5 meters)

38. Give a brief description of the GMAW process
Generally not as accurate
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
Welding process that joins metals by heating them with an electric arc
Controls the rate of flow of a shielding gas to the gun nozzle

39. What does the wire feeder control?
(DCEP) Direct Current Electrode Positive or Reverse polarity
AWS and CSA
Minutes of elapsed time continually run (out of 10 minutes)
Speed of the feed motor and - starting / stopping electrode feed

40. What does inductance control?
The Arc voltage
The time rate of response for the current rise and fall
Flux cored wires
Minutes of elapsed time continually run (out of 10 minutes)

41. What controls amperage when using GMAW?
Aluminum wire
Constant voltage (CV)
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Wire feed speed

42. Why is a line heater required when using GMAW?
Pressure vessels and the piping industry
Dry ice can form within the flow control openings and cause blockage of shielding gas
Pressure - The rate of flow of a shielding gas
Constant voltage (CV)

43. What is the recommended electrode stick- out for .035 solid wire?
Controls the rate of flow of a shielding gas to the gun nozzle
1/4 inch to 1/2 inch
The negative side of a welding unit
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

44. What power sources are used with the GMAW Process?
V groove or U groove
Motor driven generators - Transformer rectifiers - and Inverter designs
1/4 inch to 1/2 inch
Duty cycle

45. What does a flowmeter do and what does it measure?
Voltage is the force that overcomes resistance to allow amperage flow
Controls the rate of flow of a shielding gas to the gun nozzle
Minutes of elapsed time continually run (out of 10 minutes)
Short- circuiting transfer - Globular transfer - Spray transfer

46. What does the abbreviation NEMA stand for?
National Electrical Manufactures Association
V groove or U groove
Minutes of elapsed time continually run (out of 10 minutes)
Spatter problems and poor weld appearance

47. List 3 wire drive systems and give a short description of each
Duty cycle
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
Gas metal arc welding
SMAW - GTAW

48. What wire are knurled drive rolls most commonly used on?
Minimum distortion due to low heat input
Flux cored wires
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Insufficient current to melt the wire off cleanly

49. What type of power source is used with a constant speed wire feeder?
Constant voltage (CV)
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
3

50. What does voltage do in an electrical circuit?
Higher 26 to 35 arc volts
Voltage is the force that overcomes resistance to allow amperage flow
Guns
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