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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 the purpose of the pick- up lead on a voltage sensing wire feeder?
20 to 200 times per second
Gives arc voltage values to the control system of the feeder
When the filler wire is in direct contract with the base metal
Minutes of elapsed time continually run (out of 10 minutes)

2. List the three methods of metal transfer with GMAW
12 to 22 arc volts
Constant current (CC)
85%
Short- circuiting transfer - Globular transfer - Spray transfer

3. What type of power source is commonly used with a voltage sensing wire feeder?
Constant current (CC)
Constant voltage (CV)
Gives arc voltage values to the control system of the feeder
Voltage is the force that overcomes resistance to allow amperage flow

4. What does voltage do in an electrical circuit?
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
Insufficient current to melt the wire off cleanly
Voltage is the force that overcomes resistance to allow amperage flow

5. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Aluminum 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
Generally not as accurate

6. How many times per second does short circuiting take place?
Wire feed speed
Shielding the molten weld metal from atmospheric contamination
SMAW - GTAW
20 to 200 times per second

7. In the GMAW process what does voltage control?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Insufficient current to melt the wire off cleanly
Puddle fluidity
5.8 to 12.5 L/min

8. What is a solenoid valve and what actuates it?
Flux cored wires
Constant current (CC)
To prevent leakage - Carbon Dioxide (CO2)
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

9. What is the preferred drive roll design for solid wires?
V groove or U groove
To prevent leakage - Carbon Dioxide (CO2)
Cause flaking - which can clog the liner and contact tube
15 feet (4.5 meters)

10. What processes are constant current (CC) power sources designed to be used with?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Constant current (CC)
SMAW - GTAW
Minimum distortion due to low heat input

11. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
The Arc voltage
(DCEP) Direct Current Electrode Positive or Reverse polarity
Minimum distortion due to low heat input
Controls the rate of flow of a shielding gas to the gun nozzle

12. What 2 organizations designate specifications for GMAW wires?
To prevent leakage - Carbon Dioxide (CO2)
AWS and CSA
By there current carrying capacity
Voltage is the force that overcomes resistance to allow amperage flow

13. What are the 2 types of wire feeders available?
Speed of the feed motor and - starting / stopping electrode feed
Constant voltage (CV)
Aluminum wire
Constant- speed wire feeders and Voltage- sennsing wire feeders

14. What is the required arc voltage used for short circuit transfer?
The Arc voltage
The time rate of response for the current rise and fall
12 to 22 arc volts
By there current carrying capacity

15. List 3 wire drive systems and give a short description of each
These terms are quite restrictive and often technically incorrect
The Arc voltage
...
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

16. What is the key advantage of short circuiting transfer?
Reducing the gas source pressure to a constant working pressure
Pressure - The rate of flow of a shielding gas
The Arc voltage
Minimum distortion due to low heat input

17. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
If you dont know this check your phone
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

18. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
1/4 inch to 1/2 inch
Higher 26 to 35 arc volts

19. What is the purpose of a regulator and what does it indicate on its gauges?
Minutes of elapsed time continually run (out of 10 minutes)
Reducing the gas source pressure to a constant working pressure
85%
AWS and CSA

20. What would be an indication that the drive roll pressure is adjusted correctly?
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)
To limit the short circuiting current so that spatter is reduced
If you dont know this check your phone

21. In the GMAW process what does amperage control?
Short- circuiting transfer - Globular transfer - Spray transfer
15 feet (4.5 meters)
The time rate of response for the current rise and fall
Penetration and burn - off rate of the electrode

22. What does the wire feeder control?
Controls the rate of flow of a shielding gas to the gun nozzle
Speed of the feed motor and - starting / stopping electrode feed
Reducing the gas source pressure to a constant working pressure
Wire feeds smoothly (yet will slip should a problem occur in the gun)

23. Why is a line heater required when using GMAW?
Motor driven generators - Transformer rectifiers - and Inverter designs
Shielding the molten weld metal from atmospheric contamination
Constant voltage (CV)
Dry ice can form within the flow control openings and cause blockage of shielding gas

24. List several industries that would use GMAW
Pressure - The rate of flow of a shielding gas
To limit the short circuiting current so that spatter is reduced
Pressure vessels and the piping industry
Voltage is the force that overcomes resistance to allow amperage flow

25. Give a description of 'pinch effect'
Wire feed speed - Voltage control
V groove or U groove
15 feet (4.5 meters)
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

26. List the basic equipment requirements for the GMAW process
National Electrical Manufactures Association
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
To prevent drawing of liquid CO2 (Carbon Dioxide)
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

27. What does inductance control?
Puddle fluidity
The time rate of response for the current rise and fall
Voltage is the force that overcomes resistance to allow amperage flow
Insufficient current to melt the wire off cleanly

28. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
...
20 to 200 times per second
Voltage is the force that overcomes resistance to allow amperage flow
(DCEP) Direct Current Electrode Positive or Reverse polarity

29. Give a brief description of the GMAW process
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
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
Welding process that joins metals by heating them with an electric arc
V groove or U groove

30. What is the effect of too much slope?
Insufficient current to melt the wire off cleanly
When the filler wire is in direct contract with the base metal
Reducing the gas source pressure to a constant working pressure
DCEP (Direct Current Electrode Positive) Reverse Polarity

31. What current and polarity is generally used with GMAW?
Motor driven generators - Transformer rectifiers - and Inverter designs
DCEP (Direct Current Electrode Positive) Reverse Polarity
1/4 inch to 1/2 inch
12 to 22 arc volts

32. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
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)
Duty cycle
3

33. What controls amperage when using GMAW?
(DCEP) Direct Current Electrode Positive or Reverse polarity
Spatter problems and poor weld appearance
Flux cored wires
Wire feed speed

34. 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
20 to 200 times per second
The Arc voltage
By there current carrying capacity

35. What output on the welding machine is used to rate the duty cycle?
These terms are quite restrictive and often technically incorrect
Minutes of elapsed time continually run (out of 10 minutes)
To limit the short circuiting current so that spatter is reduced
Penetration and burn - off rate of the electrode

36. What type of power source is used with a constant speed wire feeder?
Wire feed speed
Constant voltage (CV)
Speed of the feed motor and - starting / stopping electrode feed
Flux cored wires

37. Draw a typical volt amp curve for a machine that is designed for GMAW
Insufficient current to melt the wire off cleanly
These terms are quite restrictive and often technically incorrect
Gives arc voltage values to the control system of the feeder
If you dont know this check your phone

38. Why must CO2 cylinders be used in the vertical position?
To prevent drawing of liquid CO2 (Carbon Dioxide)
Speed of the feed motor and - starting / stopping electrode feed
Constant voltage (CV)
Voltage is the force that overcomes resistance to allow amperage flow

39. What is a typical flow rate of CO2 for short circuit transfer?
Cause flaking - which can clog the liner and contact tube
5.8 to 12.5 L/min
The negative side of a welding unit
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

40. What controls the wire speed on a voltage sensing wire feeder?
Spatter problems and poor weld appearance
If you dont know this check your phone
The Arc voltage
Speed of the feed motor and - starting / stopping electrode feed

41. What does the abbreviation NEMA stand for?
National Electrical Manufactures Association
SMAW - GTAW
Aluminum wire
Gas metal arc welding

42. How are GMAW guns rated?
(DCEP) Direct Current Electrode Positive or Reverse polarity
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
By there current carrying capacity
Dry ice can form within the flow control openings and cause blockage of shielding gas

43. What effect does increasing and decreasing the inductance have on the weld?
Wire feed speed
Motor driven generators - Transformer rectifiers - and Inverter designs
...
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

44. Why is the term GMAW preferred over MIG or MAG?
If you dont know this check your phone
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
These terms are quite restrictive and often technically incorrect

45. Why is globular transfer generally avoided with GMAW?
If you dont know this check your phone
Spatter problems and poor weld appearance
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

46. What wire are knurled drive rolls most commonly used on?
Duty cycle
12 to 22 arc volts
Pressure - The rate of flow of a shielding gas
Flux cored wires

47. What happens when the electrode extension is increased?
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
The resistace to electrical current flow increases with it. Causing the electrode to heat
Constant- speed wire feeders and Voltage- sennsing wire feeders
Dry ice can form within the flow control openings and cause blockage of shielding gas

48. List 3 forms compressed gases may be supplied for welding
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Minimum distortion due to low heat input
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
85%

49. When is the metal transferred with short circuit transfer?
When the filler wire is in direct contract with the base metal
AWS and CSA
12 to 22 arc volts
Gas metal arc welding

50. What does a flowmeter do and what does it measure?
...
Constant voltage (CV)
Welding process that joins metals by heating them with an electric arc
Controls the rate of flow of a shielding gas to the gun nozzle