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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 controls amperage when using GMAW?
Constant- speed wire feeders and Voltage- sennsing wire feeders
Minutes of elapsed time continually run (out of 10 minutes)
Duty cycle
Wire feed speed

2. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
The negative side of a welding unit
Constant current (CC)
Cause flaking - which can clog the liner and contact tube
By there current carrying capacity

3. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
Cause flaking - which can clog the liner and contact tube
Insufficient current to melt the wire off cleanly
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
85%

4. Why is a fiber washer required and what cylinder gas requires it?
To prevent leakage - Carbon Dioxide (CO2)
3
Reducing the gas source pressure to a constant working pressure
The Arc voltage

5. What would be an indication that the drive roll pressure is adjusted correctly?
(DCEP) Direct Current Electrode Positive or Reverse polarity
1/4 inch to 1/2 inch
Puddle fluidity
Wire feeds smoothly (yet will slip should a problem occur in the gun)

6. What does inductance control?
The time rate of response for the current rise and fall
Gives arc voltage values to the control system of the feeder
Motor driven generators - Transformer rectifiers - and Inverter designs
Short- circuiting transfer - Globular transfer - Spray transfer

7. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
1/4 inch to 1/2 inch
85%
(DCEP) Direct Current Electrode Positive or Reverse polarity
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8. With straight polarity where is 2/3 of the arc energy?
The negative side of a welding unit
Duty cycle
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

9. What type of power source is used with a constant speed wire feeder?
Guns
Constant voltage (CV)
Spatter problems and poor weld appearance
Controls the rate of flow of a shielding gas to the gun nozzle

10. What does the abbreviation NEMA stand for?
National Electrical Manufactures Association
(DCEP) Direct Current Electrode Positive or Reverse polarity
Minimum distortion due to low heat input
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

11. List the three methods of metal transfer with GMAW
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Short- circuiting transfer - Globular transfer - Spray transfer
These terms are quite restrictive and often technically incorrect
The resistace to electrical current flow increases with it. Causing the electrode to heat

12. What is the purpose of the shielding gas used in GMAW?
When the filler wire is in direct contract with the base metal
Gas metal arc welding
Shielding the molten weld metal from atmospheric contamination
Cause flaking - which can clog the liner and contact tube

13. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Short- circuiting transfer - Globular transfer - Spray transfer
V groove or U groove
Duty cycle
1/4 inch to 1/2 inch

14. What effect does increasing and decreasing the inductance have on the weld?
Minimum distortion due to low heat input
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Short- circuiting transfer - Globular transfer - Spray transfer
The negative side of a welding unit

15. What is an advantage of pulsed arc transfer with GMAW?
3
To prevent leakage - Carbon Dioxide (CO2)
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
5.8 to 12.5 L/min

16. What does voltage do in an electrical circuit?
Guns
Voltage is the force that overcomes resistance to allow amperage flow
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Wire feed speed

17. What does the term GMAW identify?
Gas metal arc welding
Flux cored wires
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Motor driven generators - Transformer rectifiers - and Inverter designs

18. What type of power source is commonly used with a voltage sensing wire feeder?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
1/4 inch to 1/2 inch
Constant current (CC)
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

19. List the factors that determine the mode of metal transfer
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Constant current (CC)
Reducing the gas source pressure to a constant working pressure
Wire feed speed

20. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Higher 26 to 35 arc volts
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Guns
Welding process that joins metals by heating them with an electric arc

21. Why is a line heater required when using GMAW?
20 to 200 times per second
Dry ice can form within the flow control openings and cause blockage of shielding gas
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Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

22. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
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Voltage is the force that overcomes resistance to allow amperage flow
5.8 to 12.5 L/min
Gives arc voltage values to the control system of the feeder

23. List several industries that would use GMAW
Pressure vessels and the piping industry
Flux cored wires
Short- circuiting transfer - Globular transfer - Spray transfer
The resistace to electrical current flow increases with it. Causing the electrode to heat

24. What is another term for electrode holders for GMAW?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
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
Guns
Controls the rate of flow of a shielding gas to the gun nozzle

25. Draw a typical volt amp curve for a machine that is designed for GMAW
Generally not as accurate
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
If you dont know this check your phone
Flux cored wires

26. What does the wire feeder control?
(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
Speed of the feed motor and - starting / stopping electrode feed
To limit the short circuiting current so that spatter is reduced

27. In the GMAW process what does amperage control?
85%
Penetration and burn - off rate of the electrode
Reducing the gas source pressure to a constant working pressure
To prevent drawing of liquid CO2 (Carbon Dioxide)

28. What is the recommended electrode stick- out for .035 solid wire?
1/4 inch to 1/2 inch
12 to 22 arc volts
Pressure vessels and the piping industry
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

29. Regulators control_____________ flowmeters SHOW____________.
The resistace to electrical current flow increases with it. Causing the electrode to heat
Pressure - The rate of flow of a shielding gas
DCEP (Direct Current Electrode Positive) Reverse Polarity
Higher 26 to 35 arc volts

30. In the GMAW process what does voltage control?
To prevent drawing of liquid CO2 (Carbon Dioxide)
Puddle fluidity
Gives arc voltage values to the control system of the feeder
Spatter problems and poor weld appearance

31. What 2 controls are found on a GMAW set- up?
Spatter problems and poor weld appearance
The time rate of response for the current rise and fall
Pressure - The rate of flow of a shielding gas
Wire feed speed - Voltage control

32. What is a solenoid valve and what actuates it?
To prevent drawing of liquid CO2 (Carbon Dioxide)
DCEP (Direct Current Electrode Positive) Reverse Polarity
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Wire feed speed

33. What is the required arc voltage used for short circuit transfer?
Puddle fluidity
12 to 22 arc volts
These terms are quite restrictive and often technically incorrect
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

34. What is the preferred drive roll design for solid wires?
Generally not as accurate
Constant current (CC)
Voltage is the force that overcomes resistance to allow amperage flow
V groove or U groove

35. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
DCEP (Direct Current Electrode Positive) Reverse Polarity
Guns
To prevent drawing of liquid CO2 (Carbon Dioxide)
3

36. What power sources are used with the GMAW Process?
Wire feed speed - Voltage control
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 current (CC)
Motor driven generators - Transformer rectifiers - and Inverter designs

37. What is a typical flow rate of CO2 for short circuit transfer?
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(DCEP) Direct Current Electrode Positive or Reverse polarity
Minutes of elapsed time continually run (out of 10 minutes)
5.8 to 12.5 L/min

38. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Constant voltage (CV)
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Generally not as accurate
Insufficient current to melt the wire off cleanly

39. What 2 organizations designate specifications for GMAW wires?
12 to 22 arc volts
Puddle fluidity
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AWS and CSA

40. What is the main purpose of 'slope'?
To limit the short circuiting current so that spatter is reduced
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Motor driven generators - Transformer rectifiers - and Inverter designs
National Electrical Manufactures Association

41. When is the metal transferred with short circuit transfer?
The Arc voltage
When the filler wire is in direct contract with the base metal
12 to 22 arc volts
Reducing the gas source pressure to a constant working pressure

42. A pull type drive system is usually used on what type of material?
Guns
Speed of the feed motor and - starting / stopping electrode feed
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Aluminum wire

43. Give a brief description of the GMAW process
1/4 inch to 1/2 inch
Welding process that joins metals by heating them with an electric arc
15 feet (4.5 meters)
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

44. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
(DCEP) Direct Current Electrode Positive or Reverse polarity
Spatter problems and poor weld appearance
To prevent drawing of liquid CO2 (Carbon Dioxide)
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

45. List 3 wire drive systems and give a short description of each
Duty cycle
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
Wire feed speed - Voltage control
Cause flaking - which can clog the liner and contact tube

46. Why is the term GMAW preferred over MIG or MAG?
The negative side of a welding unit
These terms are quite restrictive and often technically incorrect
To limit the short circuiting current so that spatter is reduced
(DCEP) Direct Current Electrode Positive or Reverse polarity

47. Why is globular transfer generally avoided with GMAW?
DCEP (Direct Current Electrode Positive) Reverse Polarity
The time rate of response for the current rise and fall
Speed of the feed motor and - starting / stopping electrode feed
Spatter problems and poor weld appearance

48. List 3 forms compressed gases may be supplied for welding
To prevent leakage - Carbon Dioxide (CO2)
Generally not as accurate
15 feet (4.5 meters)
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

49. What is the purpose of a regulator and what does it indicate on its gauges?
The resistace to electrical current flow increases with it. Causing the electrode to heat
Reducing the gas source pressure to a constant working pressure
15 feet (4.5 meters)
85%

50. List the basic equipment requirements for the GMAW process
When the filler wire is in direct contract with the base metal
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
To limit the short circuiting current so that spatter is reduced
If you dont know this check your phone