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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 an advantage of pulsed arc transfer with GMAW?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Wire feed speed
To prevent leakage - Carbon Dioxide (CO2)
To limit the short circuiting current so that spatter is reduced

2. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Cause flaking - which can clog the liner and contact tube
Wire feeds smoothly (yet will slip should a problem occur in the gun)
DCEP (Direct Current Electrode Positive) Reverse Polarity
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

3. What processes are constant current (CC) power sources designed to be used with?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Puddle fluidity
Gas metal arc welding
SMAW - GTAW

4. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
12 to 22 arc volts
(DCEP) Direct Current Electrode Positive or Reverse polarity
Generally not as accurate
Minimum distortion due to low heat input

5. When is the metal transferred with short circuit transfer?
5.8 to 12.5 L/min
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When the filler wire is in direct contract with the base metal
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

6. What does the term GMAW identify?
To prevent drawing of liquid CO2 (Carbon Dioxide)
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Gas metal arc welding
Spatter problems and poor weld appearance

7. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
Guns
Duty cycle
Wire feed speed - Voltage control
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8. Why is a line heater required when using GMAW?
Dry ice can form within the flow control openings and cause blockage of shielding gas
Generally not as accurate
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Speed of the feed motor and - starting / stopping electrode feed

9. What power sources are used with the GMAW Process?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Dry ice can form within the flow control openings and cause blockage of shielding gas
The time rate of response for the current rise and fall
Motor driven generators - Transformer rectifiers - and Inverter designs

10. How are GMAW guns rated?
By there current carrying capacity
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Voltage is the force that overcomes resistance to allow amperage flow

11. What is the recommended electrode stick- out for .035 solid wire?
Higher 26 to 35 arc volts
SMAW - GTAW
Aluminum wire
1/4 inch to 1/2 inch

12. What happens when the electrode extension is increased?
The resistace to electrical current flow increases with it. Causing the electrode to heat
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Dry ice can form within the flow control openings and cause blockage of shielding gas
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

13. 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
1/4 inch to 1/2 inch
Cause flaking - which can clog the liner and contact tube
(DCEP) Direct Current Electrode Positive or Reverse polarity

14. Why must CO2 cylinders be used in the vertical position?
Pressure - The rate of flow of a shielding gas
SMAW - GTAW
To prevent drawing of liquid CO2 (Carbon Dioxide)
Flux cored wires

15. What is the main purpose of 'slope'?
Reducing the gas source pressure to a constant working pressure
To limit the short circuiting current so that spatter is reduced
15 feet (4.5 meters)
3

16. What 2 controls are found on a GMAW set- up?
Penetration and burn - off rate of the electrode
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Wire feed speed - Voltage control
SMAW - GTAW

17. What does voltage do in an electrical circuit?
Constant current (CC)
Minutes of elapsed time continually run (out of 10 minutes)
Voltage is the force that overcomes resistance to allow amperage flow
These terms are quite restrictive and often technically incorrect

18. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
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Constant- speed wire feeders and Voltage- sennsing wire feeders
85%
20 to 200 times per second

19. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
3
To prevent drawing of liquid CO2 (Carbon Dioxide)
Speed of the feed motor and - starting / stopping electrode feed

20. List 3 wire drive systems and give a short description of each
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
85%
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

21. What controls amperage when using GMAW?
Gives arc voltage values to the control system of the feeder
Wire feed speed
(DCEP) Direct Current Electrode Positive or Reverse polarity
Constant current (CC)

22. Draw a typical volt amp curve for a machine that is designed for GMAW
Penetration and burn - off rate of the electrode
Pressure - The rate of flow of a shielding gas
If you dont know this check your phone
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

23. What does a flowmeter do and what does it measure?
The Arc voltage
V groove or U groove
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Controls the rate of flow of a shielding gas to the gun nozzle

24. In the GMAW process what does voltage control?
National Electrical Manufactures Association
Pressure - The rate of flow of a shielding gas
Puddle fluidity
Wire feed speed

25. What does the abbreviation NEMA stand for?
The Arc voltage
Duty cycle
Shielding the molten weld metal from atmospheric contamination
National Electrical Manufactures Association

26. What is another term for electrode holders for GMAW?
Guns
85%
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Duty cycle

27. What is a typical flow rate of CO2 for short circuit transfer?
5.8 to 12.5 L/min
To prevent drawing of liquid CO2 (Carbon Dioxide)
These terms are quite restrictive and often technically incorrect
Wire feed speed

28. What output on the welding machine is used to rate the duty cycle?
Minutes of elapsed time continually run (out of 10 minutes)
Short- circuiting transfer - Globular transfer - Spray transfer
Duty cycle
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

29. Why is a fiber washer required and what cylinder gas requires it?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
To prevent leakage - Carbon Dioxide (CO2)
Reducing the gas source pressure to a constant working pressure
Flux cored wires

30. Give a brief description of the GMAW process
Wire feed speed
Wire feed speed - Voltage control
Welding process that joins metals by heating them with an electric arc
V groove or U groove

31. What is the preferred drive roll design for solid wires?
Puddle fluidity
Guns
V groove or U groove
Wire feed speed

32. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
3
Gives arc voltage values to the control system of the feeder
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Shielding the molten weld metal from atmospheric contamination

33. Why is the term GMAW preferred over MIG or MAG?
Generally not as accurate
Penetration and burn - off rate of the electrode
To limit the short circuiting current so that spatter is reduced
These terms are quite restrictive and often technically incorrect

34. A pull type drive system is usually used on what type of material?
Aluminum wire
85%
Speed of the feed motor and - starting / stopping electrode feed
Generally not as accurate

35. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
These terms are quite restrictive and often technically incorrect
Constant voltage (CV)
1/4 inch to 1/2 inch
Higher 26 to 35 arc volts

36. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
Controls the rate of flow of a shielding gas to the gun nozzle
If you dont know this check your phone
Aluminum wire
...

37. List the factors that determine the mode of metal transfer
85%
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Flux cored wires
15 feet (4.5 meters)

38. What is the purpose of a regulator and what does it indicate on its gauges?
Wire feed speed
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
1/4 inch to 1/2 inch
Reducing the gas source pressure to a constant working pressure

39. What type of power source is commonly used with a voltage sensing wire feeder?
Puddle fluidity
Duty cycle
Constant current (CC)
By there current carrying capacity

40. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Higher 26 to 35 arc volts
Short- circuiting transfer - Globular transfer - Spray transfer
Speed of the feed motor and - starting / stopping electrode feed
Duty cycle

41. What is the purpose of the shielding gas used in GMAW?
(DCEP) Direct Current Electrode Positive or Reverse polarity
The resistace to electrical current flow increases with it. Causing the electrode to heat
By there current carrying capacity
Shielding the molten weld metal from atmospheric contamination

42. What wire are knurled drive rolls most commonly used on?
1/4 inch to 1/2 inch
Flux cored wires
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
V groove or U groove

43. What is the effect of too much slope?
Speed of the feed motor and - starting / stopping electrode feed
20 to 200 times per second
(DCEP) Direct Current Electrode Positive or Reverse polarity
Insufficient current to melt the wire off cleanly

44. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Speed of the feed motor and - starting / stopping electrode feed
Generally not as accurate
Controls the rate of flow of a shielding gas to the gun nozzle
85%

45. List the three methods of metal transfer with GMAW
Short- circuiting transfer - Globular transfer - Spray transfer
Puddle fluidity
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
V groove or U groove

46. What are the 2 types of wire feeders available?
20 to 200 times per second
5.8 to 12.5 L/min
Constant- speed wire feeders and Voltage- sennsing wire feeders
Shielding the molten weld metal from atmospheric contamination

47. List several industries that would use GMAW
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Insufficient current to melt the wire off cleanly
Pressure vessels and the piping industry
Reducing the gas source pressure to a constant working pressure

48. What is a solenoid valve and what actuates it?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Puddle fluidity
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Motor driven generators - Transformer rectifiers - and Inverter designs

49. What type of power source is used with a constant speed wire feeder?
To limit the short circuiting current so that spatter is reduced
To prevent drawing of liquid CO2 (Carbon Dioxide)
Constant voltage (CV)
15 feet (4.5 meters)

50. What is the required arc voltage used for short circuit transfer?
AWS and CSA
Gas metal arc welding
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
12 to 22 arc volts