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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 power sources are used with the GMAW Process?
Minimum distortion due to low heat input
Motor driven generators - Transformer rectifiers - and Inverter designs
15 feet (4.5 meters)
The resistace to electrical current flow increases with it. Causing the electrode to heat

2. What wire are knurled drive rolls most commonly used on?
To prevent leakage - Carbon Dioxide (CO2)
85%
Flux cored wires
20 to 200 times per second

3. In the GMAW process what does voltage control?
Pressure - The rate of flow of a shielding gas
To prevent drawing of liquid CO2 (Carbon Dioxide)
Aluminum wire
Puddle fluidity

4. 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
20 to 200 times per second
Reducing the gas source pressure to a constant working pressure
Gas metal arc welding

5. Draw a typical volt amp curve for a machine that is designed for GMAW
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Spatter problems and poor weld appearance
12 to 22 arc volts
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6. What would be an indication that the drive roll pressure is adjusted correctly?
Duty cycle
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Wire feeds smoothly (yet will slip should a problem occur in the gun)
The negative side of a welding unit

7. How many times per second does short circuiting take place?
20 to 200 times per second
Minimum distortion due to low heat input
Penetration and burn - off rate of the electrode
Voltage is the force that overcomes resistance to allow amperage flow

8. What type of power source is used with a constant speed wire feeder?
Pressure - The rate of flow of a shielding gas
Constant voltage (CV)
Puddle fluidity
Constant- speed wire feeders and Voltage- sennsing wire feeders

9. What is the purpose of a regulator and what does it indicate on its gauges?
Reducing the gas source pressure to a constant working pressure
AWS and CSA
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
5.8 to 12.5 L/min

10. A pull type drive system is usually used on what type of material?
Reducing the gas source pressure to a constant working pressure
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
Aluminum wire

11. List the basic equipment requirements for the GMAW process
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Puddle fluidity
Reducing the gas source pressure to a constant working pressure
The resistace to electrical current flow increases with it. Causing the electrode to heat

12. What is the preferred drive roll design for solid wires?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
By there current carrying capacity
V groove or U groove
5.8 to 12.5 L/min

13. What current and polarity is generally used with GMAW?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Constant voltage (CV)
Minimum distortion due to low heat input

14. What does the term GMAW identify?
Guns
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Gas metal arc welding
SMAW - GTAW

15. What 2 controls are found on a GMAW set- up?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Wire feed speed - Voltage control
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Aluminum wire

16. What is the recommended electrode stick- out for .035 solid wire?
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
1/4 inch to 1/2 inch
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
To prevent drawing of liquid CO2 (Carbon Dioxide)

17. List the factors that determine the mode of metal transfer
Wire feed speed
5.8 to 12.5 L/min
20 to 200 times per second
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

18. Give a brief description of the GMAW process
Speed of the feed motor and - starting / stopping electrode feed
Welding process that joins metals by heating them with an electric arc
...
1/4 inch to 1/2 inch

19. What is an advantage of pulsed arc transfer with GMAW?
20 to 200 times per second
Minimum distortion due to low heat input
V groove or U groove
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

20. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
Shielding the molten weld metal from atmospheric contamination
V groove or U groove
(DCEP) Direct Current Electrode Positive or Reverse polarity
To prevent drawing of liquid CO2 (Carbon Dioxide)

21. In the GMAW process what does amperage control?
Penetration and burn - off rate of the electrode
Insufficient current to melt the wire off cleanly
The time rate of response for the current rise and fall
Gives arc voltage values to the control system of the feeder

22. What does the abbreviation NEMA stand for?
National Electrical Manufactures Association
AWS and CSA
Welding process that joins metals by heating them with an electric arc
85%

23. Why must CO2 cylinders be used in the vertical position?
Wire feed speed - Voltage control
Spatter problems and poor weld appearance
SMAW - GTAW
To prevent drawing of liquid CO2 (Carbon Dioxide)

24. Give a description of 'pinch effect'
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
National Electrical Manufactures Association
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Duty cycle

25. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
85%
Cause flaking - which can clog the liner and contact tube
...
Pressure vessels and the piping industry

26. List 3 wire drive systems and give a short description of each
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
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
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

27. What controls the wire speed on a voltage sensing wire feeder?
5.8 to 12.5 L/min
The Arc voltage
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Generally not as accurate

28. What is the purpose of the shielding gas used in GMAW?
Shielding the molten weld metal from atmospheric contamination
Cause flaking - which can clog the liner and contact tube
If you dont know this check your phone
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

29. What does a flowmeter do and what does it measure?
Dry ice can form within the flow control openings and cause blockage of shielding gas
(DCEP) Direct Current Electrode Positive or Reverse polarity
Controls the rate of flow of a shielding gas to the gun nozzle
Puddle fluidity

30. What processes are constant current (CC) power sources designed to be used with?
SMAW - GTAW
5.8 to 12.5 L/min
The Arc voltage
Gas metal arc welding

31. What is the main purpose of 'slope'?
Minimum distortion due to low heat input
To limit the short circuiting current so that spatter is reduced
Motor driven generators - Transformer rectifiers - and Inverter designs
Constant- speed wire feeders and Voltage- sennsing wire feeders

32. With straight polarity where is 2/3 of the arc energy?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
The negative side of a welding unit
Controls the rate of flow of a shielding gas to the gun nozzle
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33. 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
AWS and CSA
Controls the rate of flow of a shielding gas to the gun nozzle
The resistace to electrical current flow increases with it. Causing the electrode to heat

34. List several industries that would use GMAW
To limit the short circuiting current so that spatter is reduced
Pressure vessels and the piping industry
Welding process that joins metals by heating them with an electric arc
Gas metal arc welding

35. What is a typical flow rate of CO2 for short circuit transfer?
Gas metal arc welding
5.8 to 12.5 L/min
AWS and CSA
Reducing the gas source pressure to a constant working pressure

36. What happens when the electrode extension is increased?
The resistace to electrical current flow increases with it. Causing the electrode to heat
To prevent leakage - Carbon Dioxide (CO2)
20 to 200 times per second
12 to 22 arc volts

37. What is a solenoid valve and what actuates it?
National Electrical Manufactures Association
Welding process that joins metals by heating them with an electric arc
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Insufficient current to melt the wire off cleanly

38. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Puddle fluidity
3
Minimum distortion due to low heat input

39. Regulators control_____________ flowmeters SHOW____________.
Minimum distortion due to low heat input
Pressure - The rate of flow of a shielding gas
Gas metal arc welding
3

40. What does voltage do in an electrical circuit?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Voltage is the force that overcomes resistance to allow amperage flow
AWS and CSA
Cause flaking - which can clog the liner and contact tube

41. What effect does increasing and decreasing the inductance have on the weld?
Gives arc voltage values to the control system of the feeder
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
...
3

42. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
The Arc voltage
Higher 26 to 35 arc volts
These terms are quite restrictive and often technically incorrect
(DCEP) Direct Current Electrode Positive or Reverse polarity

43. What is another term for electrode holders for GMAW?
Guns
Minutes of elapsed time continually run (out of 10 minutes)
The Arc voltage
Reducing the gas source pressure to a constant working pressure

44. Why is globular transfer generally avoided with GMAW?
Spatter problems and poor weld appearance
(DCEP) Direct Current Electrode Positive or Reverse polarity
Aluminum wire
12 to 22 arc volts

45. Why is a line heater required when using GMAW?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Reducing the gas source pressure to a constant working pressure
Dry ice can form within the flow control openings and cause blockage of shielding gas

46. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Higher 26 to 35 arc volts
V groove or U groove
Aluminum wire
Generally not as accurate

47. List 3 forms compressed gases may be supplied for welding
Gas metal arc welding
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Cause flaking - which can clog the liner and contact tube
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

48. What controls amperage when using GMAW?
Speed of the feed motor and - starting / stopping electrode feed
Penetration and burn - off rate of the electrode
Minutes of elapsed time continually run (out of 10 minutes)
Wire feed speed

49. What is the effect of too much slope?
Insufficient current to melt the wire off cleanly
...
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
AWS and CSA

50. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
To limit the short circuiting current so that spatter is reduced
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
If you dont know this check your phone