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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. List 3 forms compressed gases may be supplied for welding
20 to 200 times per second
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
When the filler wire is in direct contract with the base metal
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

2. What current and polarity is generally used with GMAW?
Pressure - The rate of flow of a shielding gas
If you dont know this check your phone
DCEP (Direct Current Electrode Positive) Reverse Polarity
To prevent leakage - Carbon Dioxide (CO2)

3. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Higher 26 to 35 arc volts
AWS and CSA
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)

4. What is a typical flow rate of CO2 for short circuit transfer?
Reducing the gas source pressure to a constant working pressure
5.8 to 12.5 L/min
20 to 200 times per second
Guns

5. With straight polarity where is 2/3 of the arc energy?
Wire feed speed - Voltage control
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Welding process that joins metals by heating them with an electric arc
The negative side of a welding unit

6. Why is a fiber washer required and what cylinder gas requires it?
(DCEP) Direct Current Electrode Positive or Reverse polarity
Penetration and burn - off rate of the electrode
To prevent leakage - Carbon Dioxide (CO2)
15 feet (4.5 meters)

7. Regulators control_____________ flowmeters SHOW____________.
Pressure - The rate of flow of a shielding gas
When the filler wire is in direct contract with the base metal
Puddle fluidity
85%

8. What does inductance control?
The time rate of response for the current rise and fall
Reducing the gas source pressure to a constant working pressure
Speed of the feed motor and - starting / stopping electrode feed
Pressure vessels and the piping industry

9. What is the main purpose of 'slope'?
To limit the short circuiting current so that spatter is reduced
15 feet (4.5 meters)
(DCEP) Direct Current Electrode Positive or Reverse polarity
1/4 inch to 1/2 inch

10. List the three methods of metal transfer with GMAW
Short- circuiting transfer - Globular transfer - Spray transfer
Flux cored wires
1/4 inch to 1/2 inch
Gives arc voltage values to the control system of the feeder

11. What is the maximum distance that hard wire can be successfully pushed?
15 feet (4.5 meters)
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
3

12. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
To prevent leakage - Carbon Dioxide (CO2)
3
1/4 inch to 1/2 inch
The resistace to electrical current flow increases with it. Causing the electrode to heat

13. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
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
Reducing the gas source pressure to a constant working pressure

14. What is the purpose of the shielding gas used in GMAW?
Voltage is the force that overcomes resistance to allow amperage flow
Shielding the molten weld metal from atmospheric contamination
The resistace to electrical current flow increases with it. Causing the electrode to heat
Penetration and burn - off rate of the electrode

15. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
85%
Insufficient current to melt the wire off cleanly
To prevent leakage - Carbon Dioxide (CO2)

16. What does the wire feeder control?
Spatter problems and poor weld appearance
Gas metal arc welding
Shielding the molten weld metal from atmospheric contamination
Speed of the feed motor and - starting / stopping electrode feed

17. What does a flowmeter do and what does it measure?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Guns
If you dont know this check your phone
Controls the rate of flow of a shielding gas to the gun nozzle

18. What controls the wire speed on a voltage sensing wire feeder?
The time rate of response for the current rise and fall
Gives arc voltage values to the control system of the feeder
15 feet (4.5 meters)
The Arc voltage

19. What would be an indication that the drive roll pressure is adjusted correctly?
Generally not as accurate
Cause flaking - which can clog the liner and contact tube
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Constant current (CC)

20. In the GMAW process what does voltage control?
Controls the rate of flow of a shielding gas to the gun nozzle
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Puddle fluidity
20 to 200 times per second

21. What type of power source is used with a constant speed wire feeder?
Controls the rate of flow of a shielding gas to the gun nozzle
Gives arc voltage values to the control system of the feeder
Constant voltage (CV)
3

22. Why is the term GMAW preferred over MIG or MAG?
These terms are quite restrictive and often technically incorrect
Minutes of elapsed time continually run (out of 10 minutes)
The negative side of a welding unit
5.8 to 12.5 L/min

23. What does the term GMAW identify?
Gives arc voltage values to the control system of the feeder
The time rate of response for the current rise and fall
Gas metal arc welding
The Arc voltage

24. What happens when the electrode extension is increased?
The resistace to electrical current flow increases with it. Causing the electrode to heat
Insufficient current to melt the wire off cleanly
V groove or U groove
Gas metal arc welding

25. What effect does increasing and decreasing the inductance have on the weld?
Dry ice can form within the flow control openings and cause blockage of shielding gas
The negative side of a welding unit
The resistace to electrical current flow increases with it. Causing the electrode to heat
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

26. Why is a line heater required when using GMAW?
Dry ice can form within the flow control openings and cause blockage of shielding gas
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Puddle fluidity
The negative side of a welding unit

27. What output on the welding machine is used to rate the duty cycle?
5.8 to 12.5 L/min
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Minutes of elapsed time continually run (out of 10 minutes)

28. How are GMAW guns rated?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Generally not as accurate
5.8 to 12.5 L/min
By there current carrying capacity

29. What does voltage do in an electrical circuit?
12 to 22 arc volts
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Voltage is the force that overcomes resistance to allow amperage flow

30. What are the 2 types of wire feeders available?
Insufficient current to melt the wire off cleanly
Constant- speed wire feeders and Voltage- sennsing wire feeders
Dry ice can form within the flow control openings and cause blockage of shielding gas
By there current carrying capacity

31. 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
Welding process that joins metals by heating them with an electric arc
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Pressure - The rate of flow of a shielding gas

32. List several industries that would use GMAW
Constant- speed wire feeders and Voltage- sennsing wire feeders
When the filler wire is in direct contract with the base metal
Flux cored wires
Pressure vessels and the piping industry

33. What is an advantage of pulsed arc transfer with GMAW?
1/4 inch to 1/2 inch
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
5.8 to 12.5 L/min
Spatter problems and poor weld appearance

34. Why must CO2 cylinders be used in the vertical position?
If you dont know this check your phone
To prevent drawing of liquid CO2 (Carbon Dioxide)
Guns
To limit the short circuiting current so that spatter is reduced

35. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
Flux cored wires
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Speed of the feed motor and - starting / stopping electrode feed
If you dont know this check your phone

36. Give a brief description of the GMAW process
The time rate of response for the current rise and fall
15 feet (4.5 meters)
To prevent leakage - Carbon Dioxide (CO2)
Welding process that joins metals by heating them with an electric arc

37. What is the recommended electrode stick- out for .035 solid wire?
Dry ice can form within the flow control openings and cause blockage of shielding gas
5.8 to 12.5 L/min
When the filler wire is in direct contract with the base metal
1/4 inch to 1/2 inch

38. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Aluminum wire
Generally not as accurate
Shielding the molten weld metal from atmospheric contamination
To prevent drawing of liquid CO2 (Carbon Dioxide)

39. List 3 wire drive systems and give a short description of each
By there current carrying capacity
Insufficient current to melt the wire off cleanly
These terms are quite restrictive and often technically incorrect
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

40. What is the required arc voltage used for short circuit transfer?
Short- circuiting transfer - Globular transfer - Spray transfer
12 to 22 arc volts
By there current carrying capacity
Generally not as accurate

41. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
The resistace to electrical current flow increases with it. Causing the electrode to heat
Cause flaking - which can clog the liner and contact tube
The time rate of response for the current rise and fall
These terms are quite restrictive and often technically incorrect

42. What is another term for electrode holders for GMAW?
Pressure - The rate of flow of a shielding gas
Guns
Wire feeds smoothly (yet will slip should a problem occur in the gun)
By there current carrying capacity

43. What is the effect of too much slope?
If you dont know this check your phone
Reducing the gas source pressure to a constant working pressure
Insufficient current to melt the wire off cleanly
Penetration and burn - off rate of the electrode

44. What is the purpose of a regulator and what does it indicate on its gauges?
Pressure - The rate of flow of a shielding gas
Reducing the gas source pressure to a constant working pressure
Controls the rate of flow of a shielding gas to the gun nozzle
3

45. What wire are knurled drive rolls most commonly used on?
SMAW - GTAW
(DCEP) Direct Current Electrode Positive or Reverse polarity
Flux cored wires
To prevent leakage - Carbon Dioxide (CO2)

46. Draw a typical volt amp curve for a machine that is designed for GMAW
Higher 26 to 35 arc volts
Short- circuiting transfer - Globular transfer - Spray transfer
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
If you dont know this check your phone

47. What 2 organizations designate specifications for GMAW wires?
To prevent drawing of liquid CO2 (Carbon Dioxide)
AWS and CSA
Guns
12 to 22 arc volts

48. What is a solenoid valve and what actuates it?
SMAW - GTAW
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Reducing the gas source pressure to a constant working pressure
Flux cored wires

49. When is the metal transferred with short circuit transfer?
Speed of the feed motor and - starting / stopping electrode feed
Insufficient current to melt the wire off cleanly
When the filler wire is in direct contract with the base metal
Higher 26 to 35 arc volts

50. What controls amperage when using GMAW?
Puddle fluidity
To limit the short circuiting current so that spatter is reduced
AWS and CSA
Wire feed speed