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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. What would be an indication that the drive roll pressure is adjusted correctly?
Pressure vessels and the piping industry
SMAW - GTAW
AWS and CSA
Wire feeds smoothly (yet will slip should a problem occur in the gun)

2. What is a solenoid valve and what actuates it?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Insufficient current to melt the wire off cleanly
These terms are quite restrictive and often technically incorrect
Penetration and burn - off rate of the electrode

3. What does voltage do in an electrical circuit?
Minimum distortion due to low heat input
Short- circuiting transfer - Globular transfer - Spray transfer
Voltage is the force that overcomes resistance to allow amperage flow
Flux cored wires

4. What is an advantage of pulsed arc transfer with GMAW?
Aluminum wire
The resistace to electrical current flow increases with it. Causing the electrode to heat
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
DCEP (Direct Current Electrode Positive) Reverse Polarity

5. What is the key advantage of short circuiting transfer?
Shielding the molten weld metal from atmospheric contamination
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Minimum distortion due to low heat input
Controls the rate of flow of a shielding gas to the gun nozzle

6. Give a description of 'pinch effect'
Constant- speed wire feeders and Voltage- sennsing wire feeders
Gives arc voltage values to the control system of the feeder
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
20 to 200 times per second

7. What happens when the electrode extension is increased?
If you dont know this check your phone
To prevent drawing of liquid CO2 (Carbon Dioxide)
The resistace to electrical current flow increases with it. Causing the electrode to heat
The negative side of a welding unit

8. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Gas metal arc welding
Duty cycle
Short- circuiting transfer - Globular transfer - Spray transfer
Speed of the feed motor and - starting / stopping electrode feed

9. What is the preferred drive roll design for solid wires?
Constant current (CC)
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
...
V groove or U groove

10. In the GMAW process what does amperage control?
Flux cored wires
Voltage is the force that overcomes resistance to allow amperage flow
Penetration and burn - off rate of the electrode
Wire feed speed

11. Draw a typical volt amp curve for a machine that is designed for GMAW
The negative side of a welding unit
Aluminum wire
If you dont know this check your phone
Penetration and burn - off rate of the electrode

12. Why is globular transfer generally avoided with GMAW?
When the filler wire is in direct contract with the base metal
To prevent leakage - Carbon Dioxide (CO2)
...
Spatter problems and poor weld appearance

13. What does the wire feeder control?
Constant voltage (CV)
Wire feed speed - Voltage control
Short- circuiting transfer - Globular transfer - Spray transfer
Speed of the feed motor and - starting / stopping electrode feed

14. With straight polarity where is 2/3 of the arc energy?
DCEP (Direct Current Electrode Positive) Reverse Polarity
The negative side of a welding unit
Wire feed speed - Voltage control
Welding process that joins metals by heating them with an electric arc

15. What output on the welding machine is used to rate the duty cycle?
Voltage is the force that overcomes resistance to allow amperage flow
AWS and CSA
Minutes of elapsed time continually run (out of 10 minutes)
SMAW - GTAW

16. What 2 controls are found on a GMAW set- up?
National Electrical Manufactures Association
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
Wire feed speed - Voltage control

17. What 2 organizations designate specifications for GMAW wires?
The Arc voltage
Minutes of elapsed time continually run (out of 10 minutes)
AWS and CSA
V groove or U groove

18. Why is a fiber washer required and what cylinder gas requires it?
15 feet (4.5 meters)
To prevent leakage - Carbon Dioxide (CO2)
The Arc voltage
V groove or U groove

19. What current and polarity is generally used with GMAW?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Minimum distortion due to low heat input
To prevent drawing of liquid CO2 (Carbon Dioxide)
The negative side of a welding unit

20. What is the main purpose of 'slope'?
To limit the short circuiting current so that spatter is reduced
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
Minimum distortion due to low heat input

21. List the factors that determine the mode of metal transfer
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Spatter problems and poor weld appearance
Minutes of elapsed time continually run (out of 10 minutes)
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

22. List the basic equipment requirements for the GMAW process
85%
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Duty cycle
When the filler wire is in direct contract with the base metal

23. How are GMAW guns rated?
Aluminum wire
By there current carrying capacity
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Wire feed speed

24. What does the abbreviation NEMA stand for?
National Electrical Manufactures Association
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
85%
Gas metal arc welding

25. In the GMAW process what does voltage control?
...
If you dont know this check your phone
Puddle fluidity
The resistace to electrical current flow increases with it. Causing the electrode to heat

26. When is the metal transferred with short circuit transfer?
When the filler wire is in direct contract with the base metal
Motor driven generators - Transformer rectifiers - and Inverter designs
Constant voltage (CV)
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

27. 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
Minimum distortion due to low heat input
Gas metal arc welding
Reducing the gas source pressure to a constant working pressure

28. What wire are knurled drive rolls most commonly used on?
Voltage is the force that overcomes resistance to allow amperage flow
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Guns
Flux cored wires

29. What does inductance control?
By there current carrying capacity
Gives arc voltage values to the control system of the feeder
The time rate of response for the current rise and fall
Minutes of elapsed time continually run (out of 10 minutes)

30. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Higher 26 to 35 arc volts
Minutes of elapsed time continually run (out of 10 minutes)
These terms are quite restrictive and often technically incorrect
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

31. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
20 to 200 times per second
...
To prevent leakage - Carbon Dioxide (CO2)
3

32. What does a flowmeter do and what does it measure?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Pressure - The rate of flow of a shielding gas
Generally not as accurate
Controls the rate of flow of a shielding gas to the gun nozzle

33. How many times per second does short circuiting take place?
20 to 200 times per second
15 feet (4.5 meters)
Wire feed speed - Voltage control
National Electrical Manufactures Association

34. What is the effect of too much slope?
(DCEP) Direct Current Electrode Positive or Reverse polarity
Insufficient current to melt the wire off cleanly
Controls the rate of flow of a shielding gas to the gun nozzle
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. What is the purpose of a regulator and what does it indicate on its gauges?
Gives arc voltage values to the control system of the feeder
Reducing the gas source pressure to a constant working pressure
Duty cycle
Short- circuiting transfer - Globular transfer - Spray transfer

36. List 3 wire drive systems and give a short description of each
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
Guns

37. What type of power source is used with a constant speed wire feeder?
Cause flaking - which can clog the liner and contact tube
Constant voltage (CV)
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Pressure - The rate of flow of a shielding gas

38. Why is a line heater required when using GMAW?
Welding process that joins metals by heating them with an electric arc
85%
5.8 to 12.5 L/min
Dry ice can form within the flow control openings and cause blockage of shielding gas

39. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Penetration and burn - off rate of the electrode
The time rate of response for the current rise and fall
Generally not as accurate
Constant- speed wire feeders and Voltage- sennsing wire feeders

40. List 3 forms compressed gases may be supplied for welding
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
The Arc voltage
Speed of the feed motor and - starting / stopping electrode feed
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

41. Why must CO2 cylinders be used in the vertical position?
Pressure vessels and the piping industry
To prevent drawing of liquid CO2 (Carbon Dioxide)
AWS and CSA
Dry ice can form within the flow control openings and cause blockage of shielding gas

42. What controls amperage when using GMAW?
12 to 22 arc volts
Wire feed speed
Cause flaking - which can clog the liner and contact tube
Wire feed speed - Voltage control

43. What effect does increasing and decreasing the inductance have on the weld?
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Spatter problems and poor weld appearance
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Controls the rate of flow of a shielding gas to the gun nozzle

44. What controls the wire speed on a voltage sensing wire feeder?
Gas metal arc welding
SMAW - GTAW
20 to 200 times per second
The Arc voltage

45. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
Constant current (CC)
The Arc voltage
Constant voltage (CV)
If you dont know this check your phone

46. Why is the term GMAW preferred over MIG or MAG?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Puddle fluidity
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
These terms are quite restrictive and often technically incorrect

47. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Aluminum wire
If you dont know this check your phone
Cause flaking - which can clog the liner and contact tube
Guns

48. What is another term for electrode holders for GMAW?
Puddle fluidity
Guns
Constant current (CC)
Minutes of elapsed time continually run (out of 10 minutes)

49. What is the maximum distance that hard wire can be successfully pushed?
85%
Pressure - The rate of flow of a shielding gas
15 feet (4.5 meters)
Constant current (CC)

50. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
Minimum distortion due to low heat input
Welding process that joins metals by heating them with an electric arc
5.8 to 12.5 L/min
85%