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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. Why is the term GMAW preferred over MIG or MAG?
These terms are quite restrictive and often technically incorrect
Generally not as accurate
V groove or U groove
Wire feed speed

2. What does the wire feeder control?
Shielding the molten weld metal from atmospheric contamination
Speed of the feed motor and - starting / stopping electrode feed
Generally not as accurate
Higher 26 to 35 arc volts

3. What is a typical flow rate of CO2 for short circuit transfer?
Gas metal arc welding
...
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
5.8 to 12.5 L/min

4. What output on the welding machine is used to rate the duty cycle?
...
Motor driven generators - Transformer rectifiers - and Inverter designs
Minutes of elapsed time continually run (out of 10 minutes)
Wire feed speed - Voltage control

5. Why is a fiber washer required and what cylinder gas requires it?
To prevent leakage - Carbon Dioxide (CO2)
Constant current (CC)
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Penetration and burn - off rate of the electrode

6. A pull type drive system is usually used on what type of material?
By there current carrying capacity
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Aluminum wire
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

7. What is the main purpose of 'slope'?
If you dont know this check your phone
To limit the short circuiting current so that spatter is reduced
AWS and CSA
Higher 26 to 35 arc volts

8. What 2 controls are found on a GMAW set- up?
Wire feed speed - Voltage control
Guns
To prevent drawing of liquid CO2 (Carbon Dioxide)
Shielding the molten weld metal from atmospheric contamination

9. Regulators control_____________ flowmeters SHOW____________.
National Electrical Manufactures Association
The Arc voltage
Pressure - The rate of flow of a shielding gas
If you dont know this check your phone

10. In the GMAW process what does voltage control?
1/4 inch to 1/2 inch
Cause flaking - which can clog the liner and contact tube
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Puddle fluidity

11. What does inductance control?
Cause flaking - which can clog the liner and contact tube
12 to 22 arc volts
The time rate of response for the current rise and fall
Aluminum wire

12. Why must CO2 cylinders be used in the vertical position?
15 feet (4.5 meters)
By there current carrying capacity
To prevent drawing of liquid CO2 (Carbon Dioxide)
Welding process that joins metals by heating them with an electric arc

13. List several industries that would use GMAW
(DCEP) Direct Current Electrode Positive or Reverse polarity
Pressure vessels and the piping industry
When the filler wire is in direct contract with the base metal
These terms are quite restrictive and often technically incorrect

14. Give a brief description of the GMAW process
Shielding the molten weld metal from atmospheric contamination
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
(DCEP) Direct Current Electrode Positive or Reverse polarity
Welding process that joins metals by heating them with an electric arc

15. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Reducing the gas source pressure to a constant working pressure
Motor driven generators - Transformer rectifiers - and Inverter designs
These terms are quite restrictive and often technically incorrect
Higher 26 to 35 arc volts

16. What effect does increasing and decreasing the inductance have on the weld?
85%
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

17. What is the effect of too much slope?
The negative side of a welding unit
Insufficient current to melt the wire off cleanly
Gives arc voltage values to the control system of the feeder
Welding process that joins metals by heating them with an electric arc

18. How are GMAW guns rated?
By there current carrying capacity
20 to 200 times per second
Puddle fluidity
1/4 inch to 1/2 inch

19. What type of power source is commonly used with a voltage sensing wire feeder?
Constant current (CC)
Insufficient current to melt the wire off cleanly
Controls the rate of flow of a shielding gas to the gun nozzle
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

20. What type of power source is used with a constant speed wire feeder?
Constant voltage (CV)
If you dont know this check your phone
Aluminum wire
Generally not as accurate

21. What is the required arc voltage used for short circuit transfer?
12 to 22 arc volts
...
Flux cored wires
AWS and CSA

22. Why is a line heater required when using GMAW?
The Arc voltage
Dry ice can form within the flow control openings and cause blockage of shielding gas
5.8 to 12.5 L/min
Wire feed speed - Voltage control

23. Give a description of 'pinch effect'
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
85%
Pressure - The rate of flow of a shielding gas

24. List the basic equipment requirements for the GMAW process
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Voltage is the force that overcomes resistance to allow amperage flow
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Minutes of elapsed time continually run (out of 10 minutes)

25. In the GMAW process what does amperage control?
Motor driven generators - Transformer rectifiers - and Inverter designs
Penetration and burn - off rate of the electrode
Speed of the feed motor and - starting / stopping electrode feed
...

26. List 3 forms compressed gases may be supplied for welding
Minutes of elapsed time continually run (out of 10 minutes)
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Pressure - The rate of flow of a shielding gas
Flux cored wires

27. What power sources are used with the GMAW Process?
Motor driven generators - Transformer rectifiers - and Inverter designs
Gas metal arc welding
Controls the rate of flow of a shielding gas to the gun nozzle
Minutes of elapsed time continually run (out of 10 minutes)

28. What happens when the electrode extension is increased?
The resistace to electrical current flow increases with it. Causing the electrode to heat
National Electrical Manufactures Association
V groove or U groove
If you dont know this check your phone

29. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Duty cycle
Generally not as accurate
If you dont know this check your phone
Wire feeds smoothly (yet will slip should a problem occur in the gun)

30. What is the recommended electrode stick- out for .035 solid wire?
Generally not as accurate
20 to 200 times per second
1/4 inch to 1/2 inch
Speed of the feed motor and - starting / stopping electrode feed

31. 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
These terms are quite restrictive and often technically incorrect
Constant voltage (CV)
SMAW - GTAW

32. What is a solenoid valve and what actuates it?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Welding process that joins metals by heating them with an electric arc
When the filler wire is in direct contract with the base metal

33. What are the 2 types of wire feeders available?
AWS and CSA
These terms are quite restrictive and often technically incorrect
Aluminum wire
Constant- speed wire feeders and Voltage- sennsing wire feeders

34. 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
If you dont know this check your phone
V groove or U groove
The Arc voltage

35. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
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
(DCEP) Direct Current Electrode Positive or Reverse polarity
12 to 22 arc volts

36. What does voltage do in an electrical circuit?
By there current carrying capacity
Voltage is the force that overcomes resistance to allow amperage flow
These terms are quite restrictive and often technically incorrect
20 to 200 times per second

37. List the factors that determine the mode of metal transfer
20 to 200 times per second
Pressure - The rate of flow of a shielding gas
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

38. How many times per second does short circuiting take place?
(DCEP) Direct Current Electrode Positive or Reverse polarity
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
20 to 200 times per second

39. What wire are knurled drive rolls most commonly used on?
Flux cored wires
3
Guns
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

40. With straight polarity where is 2/3 of the arc energy?
...
The negative side of a welding unit
Minutes of elapsed time continually run (out of 10 minutes)
Pressure vessels and the piping industry

41. What does a flowmeter do and what does it measure?
To prevent leakage - Carbon Dioxide (CO2)
Short- circuiting transfer - Globular transfer - Spray transfer
Shielding the molten weld metal from atmospheric contamination
Controls the rate of flow of a shielding gas to the gun nozzle

42. What would be an indication that the drive roll pressure is adjusted correctly?
Constant voltage (CV)
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Voltage is the force that overcomes resistance to allow amperage flow
Constant- speed wire feeders and Voltage- sennsing wire feeders

43. What current and polarity is generally used with GMAW?
5.8 to 12.5 L/min
To limit the short circuiting current so that spatter is reduced
DCEP (Direct Current Electrode Positive) Reverse Polarity
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

44. What is the preferred drive roll design for solid wires?
Aluminum wire
Welding process that joins metals by heating them with an electric arc
V groove or U groove
Constant current (CC)

45. What is the purpose of the shielding gas used in GMAW?
85%
Minimum distortion due to low heat input
Spatter problems and poor weld appearance
Shielding the molten weld metal from atmospheric contamination

46. Why is globular transfer generally avoided with GMAW?
Cause flaking - which can clog the liner and contact tube
These terms are quite restrictive and often technically incorrect
Spatter problems and poor weld appearance
Duty cycle

47. Draw a typical volt amp curve for a machine that is designed for GMAW
Flux cored wires
If you dont know this check your phone
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Generally not as accurate

48. What controls the wire speed on a voltage sensing wire feeder?
The Arc voltage
Duty cycle
Insufficient current to melt the wire off cleanly
Wire feeds smoothly (yet will slip should a problem occur in the gun)

49. When is the metal transferred with short circuit transfer?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Wire feed speed
Duty cycle
When the filler wire is in direct contract with the base metal

50. What is another term for electrode holders for GMAW?
Constant current (CC)
Guns
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Controls the rate of flow of a shielding gas to the gun nozzle