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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. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
20 to 200 times per second
Higher 26 to 35 arc volts
Pressure - The rate of flow of a shielding gas
Pressure vessels and the piping industry

2. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
...
Guns
National Electrical Manufactures Association
Controls the rate of flow of a shielding gas to the gun nozzle

3. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
To prevent leakage - Carbon Dioxide (CO2)
Speed of the feed motor and - starting / stopping electrode feed
Cause flaking - which can clog the liner and contact tube
3

4. What is the required arc voltage used for short circuit transfer?
12 to 22 arc volts
Constant voltage (CV)
...
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5. What is the effect of too much slope?
15 feet (4.5 meters)
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
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6. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Generally not as accurate
DCEP (Direct Current Electrode Positive) Reverse Polarity
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Higher 26 to 35 arc volts

7. What processes are constant current (CC) power sources designed to be used with?
Generally not as accurate
By there current carrying capacity
SMAW - GTAW
Cause flaking - which can clog the liner and contact tube

8. What is the purpose of the shielding gas used in GMAW?
Shielding the molten weld metal from atmospheric contamination
Welding process that joins metals by heating them with an electric arc
To prevent leakage - Carbon Dioxide (CO2)
Aluminum wire

9. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Wire feed speed - Voltage control
Guns
Duty cycle
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

10. What does a flowmeter do and what does it measure?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
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
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

11. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
Dry ice can form within the flow control openings and cause blockage of shielding gas
Welding process that joins metals by heating them with an electric arc
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3

12. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
Gas metal arc welding
Minutes of elapsed time continually run (out of 10 minutes)
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Wire feeds smoothly (yet will slip should a problem occur in the gun)

13. What does the abbreviation NEMA stand for?
12 to 22 arc volts
AWS and CSA
National Electrical Manufactures Association
Penetration and burn - off rate of the electrode

14. Why is a line heater required when using GMAW?
Dry ice can form within the flow control openings and cause blockage of shielding gas
Puddle fluidity
1/4 inch to 1/2 inch
Wire feed speed - Voltage control

15. What is a typical flow rate of CO2 for short circuit transfer?
V groove or U groove
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5.8 to 12.5 L/min
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

16. What current and polarity is generally used with GMAW?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Wire feed speed - Voltage control
Insufficient current to melt the wire off cleanly
To prevent leakage - Carbon Dioxide (CO2)

17. What 2 controls are found on a GMAW set- up?
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20 to 200 times per second
Wire feed speed - Voltage control
1/4 inch to 1/2 inch

18. What is the key advantage of short circuiting transfer?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Constant current (CC)
Reducing the gas source pressure to a constant working pressure
Minimum distortion due to low heat input

19. What is the main purpose of 'slope'?
Short- circuiting transfer - Globular transfer - Spray transfer
When the filler wire is in direct contract with the base metal
Minutes of elapsed time continually run (out of 10 minutes)
To limit the short circuiting current so that spatter is reduced

20. What is the maximum distance that hard wire can be successfully pushed?
Pressure - The rate of flow of a shielding gas
To prevent leakage - Carbon Dioxide (CO2)
15 feet (4.5 meters)
The Arc voltage

21. 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
National Electrical Manufactures Association
Guns

22. List 3 forms compressed gases may be supplied for welding
The negative side of a welding unit
Wire feed speed
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
To prevent drawing of liquid CO2 (Carbon Dioxide)

23. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Gives arc voltage values to the control system of the feeder
3
To prevent leakage - Carbon Dioxide (CO2)

24. What is the purpose of a regulator and what does it indicate on its gauges?
Dry ice can form within the flow control openings and cause blockage of shielding gas
Reducing the gas source pressure to a constant working pressure
Welding process that joins metals by heating them with an electric arc
The negative side of a welding unit

25. How are GMAW guns rated?
Guns
By there current carrying capacity
Constant current (CC)
Flux cored wires

26. What controls the wire speed on a voltage sensing wire feeder?
Speed of the feed motor and - starting / stopping electrode feed
The Arc voltage
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Minutes of elapsed time continually run (out of 10 minutes)

27. What wire are knurled drive rolls most commonly used on?
Flux cored wires
Speed of the feed motor and - starting / stopping electrode feed
Wire feed speed - Voltage control
Controls the rate of flow of a shielding gas to the gun nozzle

28. When is the metal transferred with short circuit transfer?
The time rate of response for the current rise and fall
The resistace to electrical current flow increases with it. Causing the electrode to heat
(DCEP) Direct Current Electrode Positive or Reverse polarity
When the filler wire is in direct contract with the base metal

29. 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)
These terms are quite restrictive and often technically incorrect
(DCEP) Direct Current Electrode Positive or Reverse polarity
Duty cycle

30. List the basic equipment requirements for the GMAW process
To prevent leakage - Carbon Dioxide (CO2)
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
SMAW - GTAW
Constant current (CC)

31. Why is a fiber washer required and what cylinder gas requires it?
Cause flaking - which can clog the liner and contact tube
Minutes of elapsed time continually run (out of 10 minutes)
To prevent leakage - Carbon Dioxide (CO2)
Puddle fluidity

32. What type of power source is commonly used with a voltage sensing wire feeder?
To prevent leakage - Carbon Dioxide (CO2)
The negative side of a welding unit
Constant- speed wire feeders and Voltage- sennsing wire feeders
Constant current (CC)

33. Give a brief description of the GMAW process
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Wire feed speed - Voltage control
Welding process that joins metals by heating them with an electric arc
Pressure - The rate of flow of a shielding gas

34. In the GMAW process what does amperage control?
Constant voltage (CV)
Penetration and burn - off rate of the electrode
V groove or U groove
To prevent leakage - Carbon Dioxide (CO2)

35. What output on the welding machine is used to rate the duty cycle?
20 to 200 times per second
Minutes of elapsed time continually run (out of 10 minutes)
When the filler wire is in direct contract with the base metal
Wire feed speed

36. List the factors that determine the mode of metal transfer
SMAW - GTAW
Constant voltage (CV)
Penetration and burn - off rate of the electrode
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

37. Draw a typical volt amp curve for a machine that is designed for GMAW
Flux cored wires
DCEP (Direct Current Electrode Positive) Reverse Polarity
Welding process that joins metals by heating them with an electric arc
If you dont know this check your phone

38. List 3 wire drive systems and give a short description of each
Pressure vessels and the piping industry
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
Speed of the feed motor and - starting / stopping electrode feed
To prevent leakage - Carbon Dioxide (CO2)

39. What does the wire feeder control?
Speed of the feed motor and - starting / stopping electrode feed
Generally not as accurate
Puddle fluidity
Pressure - The rate of flow of a shielding gas

40. What does inductance control?
Shielding the molten weld metal from atmospheric contamination
Cause flaking - which can clog the liner and contact tube
The time rate of response for the current rise and fall
Wire feeds smoothly (yet will slip should a problem occur in the gun)

41. Why must CO2 cylinders be used in the vertical position?
Controls the rate of flow of a shielding gas to the gun nozzle
These terms are quite restrictive and often technically incorrect
To prevent drawing of liquid CO2 (Carbon Dioxide)
Duty cycle

42. What is an advantage of pulsed arc transfer with GMAW?
15 feet (4.5 meters)
Gives arc voltage values to the control system of the feeder
Higher 26 to 35 arc volts
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

43. With straight polarity where is 2/3 of the arc energy?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
V groove or U groove
The negative side of a welding unit
Insufficient current to melt the wire off cleanly

44. What is the preferred drive roll design for solid wires?
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Aluminum wire
V groove or U groove
12 to 22 arc volts

45. Regulators control_____________ flowmeters SHOW____________.
Generally not as accurate
3
Pressure - The rate of flow of a shielding gas
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

46. What controls amperage when using GMAW?
When the filler wire is in direct contract with the base metal
Wire feed speed
15 feet (4.5 meters)
(DCEP) Direct Current Electrode Positive or Reverse polarity

47. 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
Cause flaking - which can clog the liner and contact tube
Wire feed speed - Voltage control
These terms are quite restrictive and often technically incorrect

48. Why is globular transfer generally avoided with GMAW?
Insufficient current to melt the wire off cleanly
Generally not as accurate
Spatter problems and poor weld appearance
Constant current (CC)

49. What is another term for electrode holders for GMAW?
V groove or U groove
When the filler wire is in direct contract with the base metal
Guns
Welding process that joins metals by heating them with an electric arc

50. What would be an indication that the drive roll pressure is adjusted correctly?
National Electrical Manufactures Association
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
AWS and CSA
Wire feeds smoothly (yet will slip should a problem occur in the gun)