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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 a typical flow rate of CO2 for short circuit transfer?
To prevent leakage - Carbon Dioxide (CO2)
Insufficient current to melt the wire off cleanly
5.8 to 12.5 L/min
Short- circuiting transfer - Globular transfer - Spray transfer

2. What are the 2 types of wire feeders available?
Constant- speed wire feeders and Voltage- sennsing wire feeders
Spatter problems and poor weld appearance
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

3. What is the disadvantage of the gauge preset type of regulator/flowmeter?
These terms are quite restrictive and often technically incorrect
Generally not as accurate
The Arc voltage
Constant- speed wire feeders and Voltage- sennsing wire feeders

4. What output on the welding machine is used to rate the duty cycle?
Gas metal arc welding
Pressure vessels and the piping industry
Minutes of elapsed time continually run (out of 10 minutes)
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

5. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Flux cored wires
Gives arc voltage values to the control system of the feeder
National Electrical Manufactures Association
Motor driven generators - Transformer rectifiers - and Inverter designs

6. What is another term for electrode holders for GMAW?
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
Shielding the molten weld metal from atmospheric contamination
Guns

7. How many times per second does short circuiting take place?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
15 feet (4.5 meters)
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20 to 200 times per second

8. What type of power source is commonly used with a voltage sensing wire feeder?
Duty cycle
Aluminum wire
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Constant current (CC)

9. List the three methods of metal transfer with GMAW
By there current carrying capacity
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
These terms are quite restrictive and often technically incorrect
Short- circuiting transfer - Globular transfer - Spray transfer

10. Why is the term GMAW preferred over MIG or MAG?
The time rate of response for the current rise and fall
Constant voltage (CV)
These terms are quite restrictive and often technically incorrect
Voltage is the force that overcomes resistance to allow amperage flow

11. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
Wire feed speed
(DCEP) Direct Current Electrode Positive or Reverse polarity
SMAW - GTAW
Higher 26 to 35 arc volts

12. What 2 organizations designate specifications for GMAW wires?
AWS and CSA
Constant voltage (CV)
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
The resistace to electrical current flow increases with it. Causing the electrode to heat

13. In the GMAW process what does amperage control?
Penetration and burn - off rate of the electrode
Pressure - The rate of flow of a shielding gas
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Aluminum wire

14. What controls amperage when using GMAW?
V groove or U groove
Wire feed speed
Welding process that joins metals by heating them with an electric arc
Constant voltage (CV)

15. What is the maximum distance that hard wire can be successfully pushed?
Higher 26 to 35 arc volts
Short- circuiting transfer - Globular transfer - Spray transfer
15 feet (4.5 meters)
Voltage is the force that overcomes resistance to allow amperage flow

16. What power sources are used with the GMAW Process?
Puddle fluidity
DCEP (Direct Current Electrode Positive) Reverse Polarity
By there current carrying capacity
Motor driven generators - Transformer rectifiers - and Inverter designs

17. A 10 minute cycle of welding time vs cooling time a given machine can handle.
These terms are quite restrictive and often technically incorrect
Insufficient current to melt the wire off cleanly
Aluminum wire
Duty cycle

18. List the factors that determine the mode of metal transfer
5.8 to 12.5 L/min
Constant current (CC)
Flux cored wires
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

19. What controls the wire speed on a voltage sensing wire feeder?
Puddle fluidity
Pressure - The rate of flow of a shielding gas
V groove or U groove
The Arc voltage

20. With straight polarity where is 2/3 of the arc energy?
Welding process that joins metals by heating them with an electric arc
The time rate of response for the current rise and fall
The negative side of a welding unit
Shielding the molten weld metal from atmospheric contamination

21. List 3 wire drive systems and give a short description of each
The Arc voltage
Minutes of elapsed time continually run (out of 10 minutes)
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
Dry ice can form within the flow control openings and cause blockage of shielding gas

22. A pull type drive system is usually used on what type of material?
Aluminum wire
Minutes of elapsed time continually run (out of 10 minutes)
Dry ice can form within the flow control openings and cause blockage of shielding gas
Speed of the feed motor and - starting / stopping electrode feed

23. Why is globular transfer generally avoided with GMAW?
To prevent drawing of liquid CO2 (Carbon Dioxide)
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Wire feed speed
Spatter problems and poor weld appearance

24. Why is a fiber washer required and what cylinder gas requires it?
To prevent leakage - Carbon Dioxide (CO2)
12 to 22 arc volts
Duty cycle
Constant voltage (CV)

25. What 2 controls are found on a GMAW set- up?
The negative side of a welding unit
Aluminum wire
12 to 22 arc volts
Wire feed speed - Voltage control

26. Regulators control_____________ flowmeters SHOW____________.
Pressure - The rate of flow of a shielding gas
Constant voltage (CV)
Pressure vessels and the piping industry
1/4 inch to 1/2 inch

27. What wire are knurled drive rolls most commonly used on?
Flux cored wires
DCEP (Direct Current Electrode Positive) Reverse Polarity
Constant current (CC)
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28. Give a brief description of the GMAW process
Welding process that joins metals by heating them with an electric arc
The Arc voltage
V groove or U groove
Wire feed speed

29. What type of power source is used with a constant speed wire feeder?
National Electrical Manufactures Association
Constant voltage (CV)
The time rate of response for the current rise and fall
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

30. What current and polarity is generally used with GMAW?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Cause flaking - which can clog the liner and contact tube
3
5.8 to 12.5 L/min

31. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
If you dont know this check your phone
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Short- circuiting transfer - Globular transfer - Spray transfer

32. Why is a line heater required when using GMAW?
Dry ice can form within the flow control openings and cause blockage of shielding gas
Puddle fluidity
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Insufficient current to melt the wire off cleanly

33. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Wire feed speed - Voltage control
These terms are quite restrictive and often technically incorrect
Welding process that joins metals by heating them with an electric arc
Higher 26 to 35 arc volts

34. What is the purpose of the shielding gas used in GMAW?
Controls the rate of flow of a shielding gas to the gun nozzle
Shielding the molten weld metal from atmospheric contamination
Higher 26 to 35 arc volts
Minimum distortion due to low heat input

35. What is the preferred drive roll design for solid wires?
The negative side of a welding unit
V groove or U groove
Flux cored wires
85%

36. What does the abbreviation NEMA stand for?
Higher 26 to 35 arc volts
5.8 to 12.5 L/min
National Electrical Manufactures Association
Minutes of elapsed time continually run (out of 10 minutes)

37. When is the metal transferred with short circuit transfer?
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Gives arc voltage values to the control system of the feeder
National Electrical Manufactures Association
When the filler wire is in direct contract with the base metal

38. Draw a typical volt amp curve for a machine that is designed for GMAW
85%
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When the filler wire is in direct contract with the base metal
Penetration and burn - off rate of the electrode

39. What would be an indication that the drive roll pressure is adjusted correctly?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Minimum distortion due to low heat input
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Motor driven generators - Transformer rectifiers - and Inverter designs

40. In the GMAW process what does voltage control?
Puddle fluidity
AWS and CSA
Cause flaking - which can clog the liner and contact tube
Reducing the gas source pressure to a constant working pressure

41. List several industries that would use GMAW
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Pressure vessels and the piping industry
Pressure - The rate of flow of a shielding gas
Aluminum wire

42. What is the purpose of a regulator and what does it indicate on its gauges?
Insufficient current to melt the wire off cleanly
Constant voltage (CV)
5.8 to 12.5 L/min
Reducing the gas source pressure to a constant working pressure

43. What is the main purpose of 'slope'?
Penetration and burn - off rate of the electrode
To limit the short circuiting current so that spatter is reduced
Spatter problems and poor weld appearance
Cause flaking - which can clog the liner and contact tube

44. What is a solenoid valve and what actuates it?
Pressure vessels and the piping industry
Minimum distortion due to low heat input
Dry ice can form within the flow control openings and cause blockage of shielding gas
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

45. List 3 forms compressed gases may be supplied for welding
3
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Puddle fluidity
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

46. What effect does increasing and decreasing the inductance have on the weld?
Pressure vessels and the piping industry
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Constant voltage (CV)
DCEP (Direct Current Electrode Positive) Reverse Polarity

47. What does the wire feeder control?
Speed of the feed motor and - starting / stopping electrode feed
5.8 to 12.5 L/min
The negative side of a welding unit
Guns

48. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
Voltage is the force that overcomes resistance to allow amperage flow
Constant voltage (CV)
3
To prevent leakage - Carbon Dioxide (CO2)

49. What is the effect of too much slope?
Pressure - The rate of flow of a shielding gas
Guns
Insufficient current to melt the wire off cleanly
3

50. What does the term GMAW identify?
85%
Gas metal arc welding
Voltage is the force that overcomes resistance to allow amperage flow
Wire feeds smoothly (yet will slip should a problem occur in the gun)