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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
Generally not as accurate
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
To prevent drawing of liquid CO2 (Carbon Dioxide)

2. What does the wire feeder control?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Duty cycle
Wire feed speed - Voltage control
Speed of the feed motor and - starting / stopping electrode feed

3. What is the maximum distance that hard wire can be successfully pushed?
15 feet (4.5 meters)
Pressure - The rate of flow of a shielding gas
Minimum distortion due to low heat input
Penetration and burn - off rate of the electrode

4. What is the recommended electrode stick- out for .035 solid wire?
85%
1/4 inch to 1/2 inch
Pressure vessels and the piping industry
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

5. What is the purpose of a regulator and what does it indicate on its gauges?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
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
Cause flaking - which can clog the liner and contact tube

6. What current and polarity is generally used with GMAW?
DCEP (Direct Current Electrode Positive) Reverse Polarity
National Electrical Manufactures Association
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
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7. Draw a typical volt amp curve for a machine that is designed for GMAW
Wire feed speed - Voltage control
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By there current carrying capacity
20 to 200 times per second

8. What type of power source is commonly used with a voltage sensing wire feeder?
Constant current (CC)
Cause flaking - which can clog the liner and contact tube
20 to 200 times per second
12 to 22 arc volts

9. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Duty cycle
5.8 to 12.5 L/min
Wire feed speed
15 feet (4.5 meters)

10. Give a brief description of the GMAW process
Welding process that joins metals by heating them with an electric arc
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The negative side of a welding unit
By there current carrying capacity

11. List 3 forms compressed gases may be supplied for welding
Aluminum wire
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Dry ice can form within the flow control openings and cause blockage of shielding gas
Cause flaking - which can clog the liner and contact tube

12. With straight polarity where is 2/3 of the arc energy?
Constant voltage (CV)
The negative side of a welding unit
Voltage is the force that overcomes resistance to allow amperage flow
Constant- speed wire feeders and Voltage- sennsing wire feeders

13. What processes are constant current (CC) power sources designed to be used with?
Short- circuiting transfer - Globular transfer - Spray transfer
Reducing the gas source pressure to a constant working pressure
SMAW - GTAW
Speed of the feed motor and - starting / stopping electrode feed

14. What is a solenoid valve and what actuates it?
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
Penetration and burn - off rate of the electrode
Spatter problems and poor weld appearance

15. 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)
Pressure - The rate of flow of a shielding gas
Motor driven generators - Transformer rectifiers - and Inverter designs

16. How many times per second does short circuiting take place?
Pressure - The rate of flow of a shielding gas
20 to 200 times per second
Wire feed speed - Voltage control
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

17. What happens when the electrode extension is increased?
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
The resistace to electrical current flow increases with it. Causing the electrode to heat
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18. What is the main purpose of 'slope'?
Flux cored wires
Wire feed speed - Voltage control
To limit the short circuiting current so that spatter is reduced
Shielding the molten weld metal from atmospheric contamination

19. What type of power source is used with a constant speed wire feeder?
Penetration and burn - off rate of the electrode
Constant voltage (CV)
Flux cored wires
To prevent leakage - Carbon Dioxide (CO2)

20. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Gas metal arc welding
V groove or U groove
Controls the rate of flow of a shielding gas to the gun nozzle
Generally not as accurate

21. How are GMAW guns rated?
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
By there current carrying capacity
SMAW - GTAW

22. List the factors that determine the mode of metal transfer
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Motor driven generators - Transformer rectifiers - and Inverter designs
85%
The negative side of a welding unit

23. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
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Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Duty cycle
Cause flaking - which can clog the liner and contact tube

24. What does inductance control?
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Gas metal arc welding
The time rate of response for the current rise and fall
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25. What would be an indication that the drive roll pressure is adjusted correctly?
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Voltage is the force that overcomes resistance to allow amperage flow
Wire feeds smoothly (yet will slip should a problem occur in the gun)
V groove or U groove

26. What is the preferred drive roll design for solid wires?
Constant voltage (CV)
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
V groove or U groove
Short- circuiting transfer - Globular transfer - Spray transfer

27. What 2 controls are found on a GMAW set- up?
DCEP (Direct Current Electrode Positive) Reverse Polarity
12 to 22 arc volts
Gas metal arc welding
Wire feed speed - Voltage control

28. What does the term GMAW identify?
...
Gas metal arc welding
To prevent drawing of liquid CO2 (Carbon Dioxide)
These terms are quite restrictive and often technically incorrect

29. Why is globular transfer generally avoided with GMAW?
Spatter problems and poor weld appearance
15 feet (4.5 meters)
12 to 22 arc volts
The negative side of a welding unit

30. What is the required arc voltage used for short circuit transfer?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Controls the rate of flow of a shielding gas to the gun nozzle
12 to 22 arc volts
These terms are quite restrictive and often technically incorrect

31. What is the effect of too much slope?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Wire feed speed - Voltage control
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Insufficient current to melt the wire off cleanly

32. What are the 2 types of wire feeders available?
The negative side of a welding unit
Constant- speed wire feeders and Voltage- sennsing wire feeders
Higher 26 to 35 arc volts
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

33. What is an advantage of pulsed arc transfer with GMAW?
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Cause flaking - which can clog the liner and contact tube
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
DCEP (Direct Current Electrode Positive) Reverse Polarity

34. What is another term for electrode holders for GMAW?
Guns
Constant voltage (CV)
V groove or U groove
Short- circuiting transfer - Globular transfer - Spray transfer

35. When is the metal transferred with short circuit transfer?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Minutes of elapsed time continually run (out of 10 minutes)
Constant current (CC)
When the filler wire is in direct contract with the base metal

36. What 2 organizations designate specifications for GMAW wires?
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To prevent drawing of liquid CO2 (Carbon Dioxide)
AWS and CSA
The Arc voltage

37. What power sources are used with the GMAW Process?
Motor driven generators - Transformer rectifiers - and Inverter designs
DCEP (Direct Current Electrode Positive) Reverse Polarity
Minutes of elapsed time continually run (out of 10 minutes)
Wire feed speed

38. List the basic equipment requirements for the GMAW process
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
These terms are quite restrictive and often technically incorrect
Constant current (CC)
SMAW - GTAW

39. Why is a fiber washer required and what cylinder gas requires it?
The negative side of a welding unit
Wire feed speed - Voltage control
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
To prevent leakage - Carbon Dioxide (CO2)

40. What effect does increasing and decreasing the inductance have on the weld?
Reducing the gas source pressure to a constant working pressure
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
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Motor driven generators - Transformer rectifiers - and Inverter designs

41. What does voltage do in an electrical circuit?
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
Voltage is the force that overcomes resistance to allow amperage flow
20 to 200 times per second

42. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
Constant current (CC)
85%
These terms are quite restrictive and often technically incorrect
Gives arc voltage values to the control system of the feeder

43. What controls the wire speed on a voltage sensing wire feeder?
3
Controls the rate of flow of a shielding gas to the gun nozzle
The Arc voltage
When the filler wire is in direct contract with the base metal

44. Why must CO2 cylinders be used in the vertical position?
To prevent drawing of liquid CO2 (Carbon Dioxide)
Welding Current - Filler wire diameter - arc length - type of shielding - position of 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
Cause flaking - which can clog the liner and contact tube

45. Why is a line heater required when using GMAW?
Higher 26 to 35 arc volts
Dry ice can form within the flow control openings and cause blockage of shielding gas
By there current carrying capacity
If you dont know this check your phone

46. In the GMAW process what does amperage control?
Guns
The Arc voltage
Penetration and burn - off rate of the electrode
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

47. What controls amperage when using GMAW?
Voltage is the force that overcomes resistance to allow amperage flow
To prevent leakage - Carbon Dioxide (CO2)
Wire feed speed
15 feet (4.5 meters)

48. List 3 wire drive systems and give a short description of each
The Arc voltage
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Constant current (CC)
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

49. List several industries that would use 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
If you dont know this check your phone
Pressure vessels and the piping industry

50. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
Puddle fluidity
Cause flaking - which can clog the liner and contact tube
...
Minutes of elapsed time continually run (out of 10 minutes)