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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.
Don't refresh. All questions and answers are randomly picked and ordered every time you load a test.

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?
By there current carrying capacity
Controls the rate of flow of a shielding gas to the gun nozzle
5.8 to 12.5 L/min
Speed of the feed motor and - starting / stopping electrode feed

2. What 2 controls are found on a GMAW set- up?
Gives arc voltage values to the control system of the feeder
Wire feed speed - Voltage control
Pressure - The rate of flow of a shielding gas
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

3. What does the abbreviation NEMA stand for?
If you dont know this check your phone
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- speed wire feeders and Voltage- sennsing wire feeders
National Electrical Manufactures Association

4. What controls the wire speed on a voltage sensing wire feeder?
The negative side of a welding unit
Duty cycle
The Arc voltage
To prevent leakage - Carbon Dioxide (CO2)

5. How are GMAW guns rated?
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Constant- speed wire feeders and Voltage- sennsing wire feeders
The time rate of response for the current rise and fall
By there current carrying capacity

6. What is the preferred drive roll design for solid wires?
Reducing the gas source pressure to a constant working pressure
If you dont know this check your phone
The Arc voltage
V groove or U groove

7. In the GMAW process what does voltage control?
Puddle fluidity
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Gas metal arc welding
Short- circuiting transfer - Globular transfer - Spray transfer

8. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Higher 26 to 35 arc volts
National Electrical Manufactures Association
Pressure - The rate of flow of a shielding gas
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

9. What current and polarity is generally used with GMAW?
Constant voltage (CV)
DCEP (Direct Current Electrode Positive) Reverse Polarity
85%
Constant- speed wire feeders and Voltage- sennsing wire feeders

10. What is the effect of too much slope?
To prevent drawing of liquid CO2 (Carbon Dioxide)
By there current carrying capacity
85%
Insufficient current to melt the wire off cleanly

11. What would be an indication that the drive roll pressure is adjusted correctly?
15 feet (4.5 meters)
Cause flaking - which can clog the liner and contact tube
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Wire feeds smoothly (yet will slip should a problem occur in the gun)

12. Regulators control_____________ flowmeters SHOW____________.
Welding process that joins metals by heating them with an electric arc
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Pressure - The rate of flow of a shielding gas
Flux cored wires

13. What does a flowmeter do and what does it measure?
Controls the rate of flow of a shielding gas to the gun nozzle
The Arc voltage
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Minimum distortion due to low heat input

14. List the factors that determine the mode of metal transfer
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Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Motor driven generators - Transformer rectifiers - and Inverter designs
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

15. What wire are knurled drive rolls most commonly used on?
To prevent leakage - Carbon Dioxide (CO2)
Flux cored wires
To limit the short circuiting current so that spatter is reduced
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

16. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Aluminum wire
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Gives arc voltage values to the control system of the feeder

17. What 2 organizations designate specifications for GMAW wires?
AWS and CSA
Reducing the gas source pressure to a constant working pressure
Aluminum wire
The time rate of response for the current rise and fall

18. What type of power source is commonly used with a voltage sensing wire feeder?
Generally not as accurate
5.8 to 12.5 L/min
Constant current (CC)
20 to 200 times per second

19. List 3 wire drive systems and give a short description of each
1/4 inch to 1/2 inch
Pressure - The rate of flow of a shielding gas
Speed of the feed motor and - starting / stopping electrode feed
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

20. What processes are constant current (CC) power sources designed to be used with?
Duty cycle
Pressure - The rate of flow of a shielding gas
SMAW - GTAW
Generally not as accurate

21. What is the key advantage of short circuiting transfer?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
National Electrical Manufactures Association
The time rate of response for the current rise and fall
Minimum distortion due to low heat input

22. How many times per second does short circuiting take place?
National Electrical Manufactures Association
Flux cored wires
20 to 200 times per second
Gives arc voltage values to the control system of the feeder

23. List 3 forms compressed gases may be supplied for welding
Constant current (CC)
(DCEP) Direct Current Electrode Positive or Reverse polarity
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

24. What does inductance control?
Welding process that joins metals by heating them with an electric arc
Motor driven generators - Transformer rectifiers - and Inverter designs
V groove or U groove
The time rate of response for the current rise and fall

25. List several industries that would use GMAW
Generally not as accurate
Cause flaking - which can clog the liner and contact tube
Aluminum wire
Pressure vessels and the piping industry

26. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
SMAW - GTAW
Motor driven generators - Transformer rectifiers - and Inverter designs
...
Puddle fluidity

27. What is a solenoid valve and what actuates it?
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
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Short- circuiting transfer - Globular transfer - Spray transfer

28. What does the wire feeder control?
Speed of the feed motor and - starting / stopping electrode feed
National Electrical Manufactures Association
Guns
20 to 200 times per second

29. What is an advantage of pulsed arc transfer with GMAW?
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
Minutes of elapsed time continually run (out of 10 minutes)
Gas metal arc welding

30. Give a description of 'pinch effect'
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
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
15 feet (4.5 meters)

31. Draw a typical volt amp curve for a machine that is designed for GMAW
SMAW - GTAW
The resistace to electrical current flow increases with it. Causing the electrode to heat
If you dont know this check your phone
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

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
Voltage is the force that overcomes resistance to allow amperage flow
Penetration and burn - off rate of the electrode
Reducing the gas source pressure to a constant working pressure

33. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
Motor driven generators - Transformer rectifiers - and Inverter designs
20 to 200 times per second
...
If you dont know this check your phone

34. What controls amperage when using GMAW?
1/4 inch to 1/2 inch
National Electrical Manufactures Association
Wire feed speed
Wire feed speed - Voltage control

35. Why is a fiber washer required and what cylinder gas requires it?
To prevent leakage - Carbon Dioxide (CO2)
20 to 200 times per second
15 feet (4.5 meters)
Cause flaking - which can clog the liner and contact tube

36. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Flux cored wires
Dry ice can form within the flow control openings and cause blockage of shielding gas
Constant voltage (CV)
Generally not as accurate

37. What does voltage do in an electrical circuit?
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
DCEP (Direct Current Electrode Positive) Reverse Polarity
When the filler wire is in direct contract with the base metal
Voltage is the force that overcomes resistance to allow amperage flow

38. List the three methods of metal transfer with GMAW
To prevent drawing of liquid CO2 (Carbon Dioxide)
Minutes of elapsed time continually run (out of 10 minutes)
These terms are quite restrictive and often technically incorrect
Short- circuiting transfer - Globular transfer - Spray transfer

39. 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
15 feet (4.5 meters)
Short- circuiting transfer - Globular transfer - Spray transfer
The resistace to electrical current flow increases with it. Causing the electrode to heat

40. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
Flux cored wires
Constant current (CC)
(DCEP) Direct Current Electrode Positive or Reverse polarity
Penetration and burn - off rate of the electrode

41. What is the maximum distance that hard wire can be successfully pushed?
Controls the rate of flow of a shielding gas to the gun nozzle
SMAW - GTAW
Minimum distortion due to low heat input
15 feet (4.5 meters)

42. What is the required arc voltage used for short circuit transfer?
Minutes of elapsed time continually run (out of 10 minutes)
12 to 22 arc volts
Wire feed speed
Controls the rate of flow of a shielding gas to the gun nozzle

43. With straight polarity where is 2/3 of the arc energy?
If you dont know this check your phone
15 feet (4.5 meters)
1/4 inch to 1/2 inch
The negative side of a welding unit

44. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
Insufficient current to melt the wire off cleanly
...
85%
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

45. What are the 2 types of wire feeders available?
Constant- speed wire feeders and Voltage- sennsing wire feeders
Constant current (CC)
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Generally not as accurate

46. What effect does increasing and decreasing the inductance have on the weld?
Constant current (CC)
Dry ice can form within the flow control openings and cause blockage of shielding gas
If you dont know this check your phone
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

47. What is the purpose of the shielding gas used in GMAW?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Short- circuiting transfer - Globular transfer - Spray transfer
Shielding the molten weld metal from atmospheric contamination
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

48. What output on the welding machine is used to rate the duty cycle?
Wire feed speed
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Minutes of elapsed time continually run (out of 10 minutes)
15 feet (4.5 meters)

49. What is the main purpose of 'slope'?
Constant- speed wire feeders and Voltage- sennsing wire feeders
To limit the short circuiting current so that spatter is reduced
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
The Arc voltage

50. Why is globular transfer generally avoided with GMAW?
Voltage is the force that overcomes resistance to allow amperage flow
Spatter problems and poor weld appearance
12 to 22 arc volts
Aluminum wire