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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. What wire are knurled drive rolls most commonly used on?
Flux cored wires
Minutes of elapsed time continually run (out of 10 minutes)
85%
Speed of the feed motor and - starting / stopping electrode feed

2. List the basic equipment requirements for the GMAW process
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Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
(DCEP) Direct Current Electrode Positive or Reverse polarity
Welding process that joins metals by heating them with an electric arc

3. What is the recommended electrode stick- out for .035 solid wire?
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Dry ice can form within the flow control openings and cause blockage of shielding gas
1/4 inch to 1/2 inch
SMAW - GTAW

4. What controls the wire speed on a voltage sensing wire feeder?
Speed of the feed motor and - starting / stopping electrode feed
The Arc voltage
Penetration and burn - off rate of the electrode
Reducing the gas source pressure to a constant working pressure

5. What effect does increasing and decreasing the inductance have on the weld?
Constant voltage (CV)
Gives arc voltage values to the control system of the 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
By there current carrying capacity

6. What is the maximum distance that hard wire can be successfully pushed?
5.8 to 12.5 L/min
Constant current (CC)
The time rate of response for the current rise and fall
15 feet (4.5 meters)

7. In the GMAW process what does amperage control?
Penetration and burn - off rate of the electrode
Wire feed speed - Voltage control
20 to 200 times per second
Shielding the molten weld metal from atmospheric contamination

8. What does voltage do in an electrical circuit?
Penetration and burn - off rate of the electrode
Flux cored wires
Voltage is the force that overcomes resistance to allow amperage flow
Constant- speed wire feeders and Voltage- sennsing wire feeders

9. What is the purpose of the shielding gas used in GMAW?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Shielding the molten weld metal from atmospheric contamination
Controls the rate of flow of a shielding gas to the gun nozzle
20 to 200 times per second

10. What does a flowmeter do and what does it measure?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Controls the rate of flow of a shielding gas to the gun nozzle
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Puddle fluidity

11. List 3 forms compressed gases may be supplied for welding
Minutes of elapsed time continually run (out of 10 minutes)
Pressure vessels and the piping industry
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
AWS and CSA

12. What is the preferred drive roll design for solid wires?
V groove or U groove
AWS and CSA
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Higher 26 to 35 arc volts

13. What would be an indication that the drive roll pressure is adjusted correctly?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
12 to 22 arc volts
Insufficient current to melt the wire off cleanly
DCEP (Direct Current Electrode Positive) Reverse Polarity

14. What does inductance 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
The time rate of response for the current rise and fall
Short- circuiting transfer - Globular transfer - Spray transfer

15. What is the main purpose of 'slope'?
To limit the short circuiting current so that spatter is reduced
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
Aluminum wire

16. How many times per second does short circuiting take place?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
SMAW - GTAW
Constant- speed wire feeders and Voltage- sennsing wire feeders
20 to 200 times per second

17. When is the metal transferred with short circuit transfer?
When the filler wire is in direct contract with the base metal
National Electrical Manufactures Association
Wire feed speed - Voltage control
85%

18. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Wire feed speed - Voltage control
To prevent leakage - Carbon Dioxide (CO2)
By there current carrying capacity
Cause flaking - which can clog the liner and contact tube

19. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
...
By there current carrying capacity
V groove or U groove
Constant current (CC)

20. What are the 2 types of wire feeders available?
National Electrical Manufactures Association
When the filler wire is in direct contract with the base metal
Constant- speed wire feeders and Voltage- sennsing wire feeders
Duty cycle

21. Give a brief description of the GMAW process
Higher 26 to 35 arc volts
Welding process that joins metals by heating them with an electric arc
The Arc voltage
To prevent drawing of liquid CO2 (Carbon Dioxide)

22. What is an advantage of pulsed arc transfer with GMAW?
(DCEP) Direct Current Electrode Positive or Reverse polarity
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
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

23. What 2 organizations designate specifications for GMAW wires?
Wire feed speed
AWS and CSA
Voltage is the force that overcomes resistance to allow amperage flow
National Electrical Manufactures Association

24. Why is globular transfer generally avoided with GMAW?
Reducing the gas source pressure to a constant working pressure
Spatter problems and poor weld appearance
(DCEP) Direct Current Electrode Positive or Reverse polarity
To limit the short circuiting current so that spatter is reduced

25. What is the required arc voltage used for short circuit transfer?
Penetration and burn - off rate of the electrode
Minimum distortion due to low heat input
To limit the short circuiting current so that spatter is reduced
12 to 22 arc volts

26. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
The resistace to electrical current flow increases with it. Causing the electrode to heat
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These terms are quite restrictive and often technically incorrect
Welding process that joins metals by heating them with an electric arc

27. How are GMAW guns rated?
Gives arc voltage values to the control system of the feeder
Aluminum wire
If you dont know this check your phone
By there current carrying capacity

28. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Aluminum wire
Duty cycle
Constant current (CC)

29. What is the key advantage of short circuiting transfer?
AWS and CSA
Minimum distortion due to low heat input
12 to 22 arc volts
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

30. What is the purpose of a regulator and what does it indicate on its gauges?
85%
Guns
Reducing the gas source pressure to a constant working pressure
(DCEP) Direct Current Electrode Positive or Reverse polarity

31. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
Welding process that joins metals by heating them with an electric arc
Speed of the feed motor and - starting / stopping electrode feed
5.8 to 12.5 L/min
3

32. List the three methods of metal transfer with GMAW
Short- circuiting transfer - Globular transfer - Spray transfer
85%
15 feet (4.5 meters)
(DCEP) Direct Current Electrode Positive or Reverse polarity

33. Why is a fiber washer required and what cylinder gas requires it?
DCEP (Direct Current Electrode Positive) Reverse Polarity
To prevent leakage - Carbon Dioxide (CO2)
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

34. What processes are constant current (CC) power sources designed to be used with?
SMAW - GTAW
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Insufficient current to melt the wire off cleanly
Constant current (CC)

35. What is a typical flow rate of CO2 for short circuit transfer?
Welding process that joins metals by heating them with an electric arc
(DCEP) Direct Current Electrode Positive or Reverse polarity
5.8 to 12.5 L/min
AWS and CSA

36. List several industries that would use GMAW
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Pressure vessels and the piping industry
Short- circuiting transfer - Globular transfer - Spray transfer
Constant current (CC)

37. With straight polarity where is 2/3 of the arc energy?
20 to 200 times per second
Pressure vessels and the piping industry
5.8 to 12.5 L/min
The negative side of a welding unit

38. Regulators control_____________ flowmeters SHOW____________.
Pressure - The rate of flow of a shielding gas
Wire feeds smoothly (yet will slip should a problem occur in the gun)
The negative side of a welding unit
If you dont know this check your phone

39. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Higher 26 to 35 arc volts
Guns
85%

40. Give a description of 'pinch effect'
AWS and CSA
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
The negative side of a welding unit
Dry ice can form within the flow control openings and cause blockage of shielding gas

41. Why is a line heater required when using GMAW?
15 feet (4.5 meters)
Dry ice can form within the flow control openings and cause blockage of shielding gas
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Speed of the feed motor and - starting / stopping electrode feed

42. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Higher 26 to 35 arc volts
Pressure - The rate of flow of a shielding gas
Spatter problems and poor weld appearance
Pressure vessels and the piping industry

43. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
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
85%
20 to 200 times per second

44. Why must CO2 cylinders be used in the vertical position?
To prevent drawing of liquid CO2 (Carbon Dioxide)
SMAW - GTAW
The time rate of response for the current rise and fall
5.8 to 12.5 L/min

45. What controls amperage when using GMAW?
By there current carrying capacity
Generally not as accurate
Wire feed speed
3

46. Draw a typical volt amp curve for a machine that is designed for GMAW
Cause flaking - which can clog the liner and contact tube
Controls the rate of flow of a shielding gas to the gun nozzle
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
If you dont know this check your phone

47. What is a solenoid valve and what actuates it?
Constant- speed wire feeders and Voltage- sennsing wire feeders
SMAW - GTAW
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

48. What happens when the electrode extension is increased?
To prevent drawing of liquid CO2 (Carbon Dioxide)
The resistace to electrical current flow increases with it. Causing the electrode to heat
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

49. In the GMAW process what does voltage control?
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
Flux cored wires
Gives arc voltage values to the control system of the feeder
Puddle fluidity

50. What type of power source is used with a constant speed wire feeder?
Puddle fluidity
Constant voltage (CV)
20 to 200 times per second
Dry ice can form within the flow control openings and cause blockage of shielding gas