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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 is the main purpose of 'slope'?
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These terms are quite restrictive and often technically incorrect
The time rate of response for the current rise and fall
To limit the short circuiting current so that spatter is reduced

2. List the factors that determine the mode of metal transfer
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Pressure - The rate of flow of a shielding gas
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

3. What is the purpose of the shielding gas used in GMAW?
20 to 200 times per second
To prevent drawing of liquid CO2 (Carbon Dioxide)
Shielding the molten weld metal from atmospheric contamination
Spatter problems and poor weld appearance

4. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Motor driven generators - Transformer rectifiers - and Inverter designs
Generally not as accurate
Wire feed speed
1/4 inch to 1/2 inch

5. What is the effect of too much slope?
Insufficient current to melt the wire off cleanly
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Constant voltage (CV)
Flux cored wires

6. List several industries that would use GMAW
Gas metal arc welding
12 to 22 arc volts
Reducing the gas source pressure to a constant working pressure
Pressure vessels and the piping industry

7. Why is globular transfer generally avoided with GMAW?
These terms are quite restrictive and often technically incorrect
Puddle fluidity
Spatter problems and poor weld appearance
Insufficient current to melt the wire off cleanly

8. What is another term for electrode holders for GMAW?
Cause flaking - which can clog the liner and contact tube
These terms are quite restrictive and often technically incorrect
Guns
National Electrical Manufactures Association

9. What does the term GMAW identify?
To limit the short circuiting current so that spatter is reduced
Gas metal arc welding
By there current carrying capacity
Generally not as accurate

10. What is the preferred drive roll design for solid wires?
Generally not as accurate
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To limit the short circuiting current so that spatter is reduced
V groove or U groove

11. What power sources are used with the GMAW Process?
Constant voltage (CV)
Motor driven generators - Transformer rectifiers - and Inverter designs
Controls the rate of flow of a shielding gas to the gun nozzle
Aluminum wire

12. A pull type drive system is usually used on what type of material?
Shielding the molten weld metal from atmospheric contamination
Gas metal arc welding
Aluminum wire
When the filler wire is in direct contract with the base metal

13. What controls amperage when using GMAW?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Short- circuiting transfer - Globular transfer - Spray transfer
Shielding the molten weld metal from atmospheric contamination
Wire feed speed

14. What does a flowmeter do and what does it measure?
Controls the rate of flow of a shielding gas to the gun nozzle
Insufficient current to melt the wire off cleanly
To prevent drawing of liquid CO2 (Carbon Dioxide)
Shielding the molten weld metal from atmospheric contamination

15. List 3 wire drive systems and give a short description of each
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
Pressure - The rate of flow of a shielding gas
Voltage is the force that overcomes resistance to allow amperage flow
Short- circuiting transfer - Globular transfer - Spray transfer

16. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Duty cycle
5.8 to 12.5 L/min
(DCEP) Direct Current Electrode Positive or Reverse polarity
3

17. What happens when the electrode extension is increased?
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
5.8 to 12.5 L/min
The resistace to electrical current flow increases with it. Causing the electrode to heat

18. What does inductance control?
SMAW - GTAW
To prevent drawing of liquid CO2 (Carbon Dioxide)
The time rate of response for the current rise and fall
85%

19. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
Speed of the feed motor and - starting / stopping electrode feed
Aluminum wire
Pressure - The rate of flow of a shielding gas
3

20. Draw a typical volt amp curve for a machine that is designed for GMAW
The Arc voltage
The resistace to electrical current flow increases with it. Causing the electrode to heat
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Puddle fluidity

21. 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
Penetration and burn - off rate of the electrode
1/4 inch to 1/2 inch
V groove or U groove

22. What type of power source is used with a constant speed wire feeder?
V groove or U groove
Constant voltage (CV)
Higher 26 to 35 arc volts
Insufficient current to melt the wire off cleanly

23. What controls the wire speed on a voltage sensing wire feeder?
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Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Gas metal arc welding
The Arc voltage

24. What are the 2 types of wire feeders available?
To prevent leakage - Carbon Dioxide (CO2)
Constant- speed wire feeders and Voltage- sennsing wire feeders
Puddle fluidity
V groove or U groove

25. Why is a line heater required when using GMAW?
Dry ice can form within the flow control openings and cause blockage of shielding gas
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
Penetration and burn - off rate of the electrode
The negative side of a welding unit

26. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
85%
To prevent leakage - Carbon Dioxide (CO2)
Penetration and burn - off rate of the electrode
Controls the rate of flow of a shielding gas to the gun nozzle

27. What is an advantage of pulsed arc transfer with GMAW?
Voltage is the force that overcomes resistance to allow amperage flow
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

28. What is a typical flow rate of CO2 for short circuit transfer?
5.8 to 12.5 L/min
To limit the short circuiting current so that spatter is reduced
Welding process that joins metals by heating them with an electric arc
Wire feeds smoothly (yet will slip should a problem occur in the gun)

29. How many times per second does short circuiting take place?
20 to 200 times per second
The negative side of a welding unit
5.8 to 12.5 L/min
15 feet (4.5 meters)

30. In the GMAW process what does amperage control?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
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
Penetration and burn - off rate of the electrode

31. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
SMAW - GTAW
(DCEP) Direct Current Electrode Positive or Reverse polarity
By there current carrying capacity
Guns

32. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Reducing the gas source pressure to a constant working pressure
Cause flaking - which can clog the liner and contact tube
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

33. Give a brief description of the GMAW process
When the filler wire is in direct contract with the base metal
Minutes of elapsed time continually run (out of 10 minutes)
Welding process that joins metals by heating them with an electric arc
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

34. When is the metal transferred with short circuit transfer?
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
Guns
If you dont know this check your phone

35. What does voltage do in an electrical circuit?
...
Penetration and burn - off rate of the electrode
Voltage is the force that overcomes resistance to allow amperage flow
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

36. Why must CO2 cylinders be used in the vertical position?
Speed of the feed motor and - starting / stopping electrode feed
Wire feed speed - Voltage control
To prevent drawing of liquid CO2 (Carbon Dioxide)
Minimum distortion due to low heat input

37. In the GMAW process what does voltage control?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Penetration and burn - off rate of the electrode
DCEP (Direct Current Electrode Positive) Reverse Polarity
Puddle fluidity

38. Why is a fiber washer required and what cylinder gas requires it?
To prevent leakage - Carbon Dioxide (CO2)
15 feet (4.5 meters)
Duty cycle
Gives arc voltage values to the control system of the feeder

39. What is the required arc voltage used for short circuit transfer?
Generally not as accurate
12 to 22 arc volts
Puddle fluidity
Constant voltage (CV)

40. What is the key advantage of short circuiting transfer?
12 to 22 arc volts
Minimum distortion due to low heat input
Controls the rate of flow of a shielding gas to the gun nozzle
The negative side of a welding unit

41. What would be an indication that the drive roll pressure is adjusted correctly?
The Arc voltage
Wire feeds smoothly (yet will slip should a problem occur in the gun)
If you dont know this check your phone
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

42. What type of power source is commonly used with a voltage sensing wire feeder?
Controls the rate of flow of a shielding gas to the gun nozzle
Puddle fluidity
Constant current (CC)
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

43. 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
To prevent drawing of liquid CO2 (Carbon Dioxide)
85%
Short- circuiting transfer - Globular transfer - Spray transfer

44. What is the purpose of a regulator and what does it indicate on its gauges?
Higher 26 to 35 arc volts
Reducing the gas source pressure to a constant working pressure
(DCEP) Direct Current Electrode Positive or Reverse polarity
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

45. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Higher 26 to 35 arc volts
National Electrical Manufactures Association
Spatter problems and poor weld appearance
Voltage is the force that overcomes resistance to allow amperage flow

46. What processes are constant current (CC) power sources designed to be used with?
3
Aluminum wire
15 feet (4.5 meters)
SMAW - GTAW

47. 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
Speed of the feed motor and - starting / stopping electrode feed
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

48. 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
Minutes of elapsed time continually run (out of 10 minutes)
V groove or U groove
If you dont know this check your phone

49. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
Flux cored wires
...
Minimum distortion due to low heat input
Speed of the feed motor and - starting / stopping electrode feed

50. What 2 organizations designate specifications for GMAW wires?
AWS and CSA
To limit the short circuiting current so that spatter is reduced
Voltage is the force that overcomes resistance to allow amperage flow
Wire feed speed