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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. List the three methods of metal transfer with GMAW
Short- circuiting transfer - Globular transfer - Spray transfer
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Minutes of elapsed time continually run (out of 10 minutes)
Wire feed speed

2. What current and polarity is generally used with GMAW?
DCEP (Direct Current Electrode Positive) Reverse Polarity
12 to 22 arc volts
20 to 200 times per second
15 feet (4.5 meters)

3. Why is globular transfer generally avoided with GMAW?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Puddle fluidity
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Spatter problems and poor weld appearance

4. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
Spatter problems and poor weld appearance
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Minutes of elapsed time continually run (out of 10 minutes)
3

5. What effect does increasing and decreasing the inductance have on the weld?
Shielding the molten weld metal from atmospheric contamination
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Speed of the feed motor and - starting / stopping electrode feed
Pressure - The rate of flow of a shielding gas

6. What is the required arc voltage used for short circuit transfer?
85%
12 to 22 arc volts
Aluminum wire
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

7. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Insufficient current to melt the wire off cleanly
Higher 26 to 35 arc volts
Duty cycle
3

8. How are GMAW guns rated?
Wire feed speed - Voltage control
Puddle fluidity
If you dont know this check your phone
By there current carrying capacity

9. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Constant voltage (CV)
Higher 26 to 35 arc volts
Reducing the gas source pressure to a constant working pressure

10. A pull type drive system is usually used on what type of material?
Pressure vessels and the piping industry
Aluminum wire
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Constant- speed wire feeders and Voltage- sennsing wire feeders

11. What does the abbreviation NEMA stand for?
Pressure vessels and the piping industry
National Electrical Manufactures Association
Aluminum wire
15 feet (4.5 meters)

12. Give a brief description of the GMAW process
Constant voltage (CV)
Welding process that joins metals by heating them with an electric arc
To limit the short circuiting current so that spatter is reduced
Generally not as accurate

13. List 3 forms compressed gases may be supplied for welding
Shielding the molten weld metal from atmospheric contamination
The time rate of response for the current rise and fall
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Pressure vessels and the piping industry

14. What does a flowmeter do and what does it measure?
If you dont know this check your phone
Cause flaking - which can clog the liner and contact tube
Gas metal arc welding
Controls the rate of flow of a shielding gas to the gun nozzle

15. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Pressure vessels and the piping industry
The resistace to electrical current flow increases with it. Causing the electrode to heat
Generally not as accurate

16. What does inductance control?
The time rate of response for the current rise and fall
20 to 200 times per second
Gas metal arc welding
Pressure - The rate of flow of a shielding gas

17. What is the key advantage of short circuiting transfer?
Minimum distortion due to low heat input
Speed of the feed motor and - starting / stopping electrode feed
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

18. What is a typical flow rate of CO2 for short circuit transfer?
12 to 22 arc volts
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
5.8 to 12.5 L/min

19. 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
Short- circuiting transfer - Globular transfer - Spray transfer
By there current carrying capacity
V groove or U groove

20. With straight polarity where is 2/3 of the arc energy?
By there current carrying capacity
The negative side of a welding unit
Guns
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

21. What is the recommended electrode stick- out for .035 solid wire?
If you dont know this check your phone
Pressure vessels and the piping industry
Pressure - The rate of flow of a shielding gas
1/4 inch to 1/2 inch

22. What is the main purpose of 'slope'?
To limit the short circuiting current so that spatter is reduced
Pressure - The rate of flow of a shielding gas
Reducing the gas source pressure to a constant working pressure
Wire feeds smoothly (yet will slip should a problem occur in the gun)

23. What is the purpose of the shielding gas used in GMAW?
Constant voltage (CV)
To prevent drawing of liquid CO2 (Carbon Dioxide)
Wire feed speed - Voltage control
Shielding the molten weld metal from atmospheric contamination

24. List several industries that would use GMAW
Speed of the feed motor and - starting / stopping electrode feed
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Minutes of elapsed time continually run (out of 10 minutes)
Pressure vessels and the piping industry

25. What is another term for electrode holders for GMAW?
If you dont know this check your phone
Pressure vessels and the piping industry
Guns
DCEP (Direct Current Electrode Positive) Reverse Polarity

26. Draw a typical volt amp curve for a machine that is designed for GMAW
To limit the short circuiting current so that spatter is reduced
If you dont know this check your phone
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Guns

27. Why must CO2 cylinders be used in the vertical position?
To prevent drawing of liquid CO2 (Carbon Dioxide)
AWS and CSA
Penetration and burn - off rate of the electrode
Generally not as accurate

28. What is a solenoid valve and what actuates it?
Generally not as accurate
To prevent leakage - Carbon Dioxide (CO2)
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

29. List the basic equipment requirements for the GMAW process
These terms are quite restrictive and often technically incorrect
...
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Guns

30. In the GMAW process what does voltage control?
Puddle fluidity
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
To prevent drawing of liquid CO2 (Carbon Dioxide)
Short- circuiting transfer - Globular transfer - Spray transfer

31. What type of power source is commonly used with a voltage sensing wire feeder?
15 feet (4.5 meters)
Constant current (CC)
Reducing the gas source pressure to a constant working pressure
Spatter problems and poor weld appearance

32. What would be an indication that the drive roll pressure is adjusted correctly?
Guns
Penetration and burn - off rate of the electrode
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Puddle fluidity

33. What controls amperage when using GMAW?
Guns
Wire feed speed
Spatter problems and poor weld appearance
Pressure vessels and the piping industry

34. Why is a fiber washer required and what cylinder gas requires it?
20 to 200 times per second
Aluminum wire
Controls the rate of flow of a shielding gas to the gun nozzle
To prevent leakage - Carbon Dioxide (CO2)

35. Why is the term GMAW preferred over MIG or MAG?
These terms are quite restrictive and often technically incorrect
15 feet (4.5 meters)
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Shielding the molten weld metal from atmospheric contamination

36. Give a description of 'pinch effect'
(DCEP) Direct Current Electrode Positive or Reverse polarity
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Constant voltage (CV)
20 to 200 times per second

37. What is the maximum distance that hard wire can be successfully pushed?
15 feet (4.5 meters)
Cause flaking - which can clog the liner and contact tube
Wire feed speed - Voltage control
20 to 200 times per second

38. What is an advantage of pulsed arc transfer with GMAW?
Short- circuiting transfer - Globular transfer - Spray transfer
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
85%
5.8 to 12.5 L/min

39. What is the effect of too much slope?
The resistace to electrical current flow increases with it. Causing the electrode to heat
Insufficient current to melt the wire off cleanly
SMAW - GTAW
Voltage is the force that overcomes resistance to allow amperage flow

40. What 2 organizations designate specifications for GMAW wires?
Minimum distortion due to low heat input
Generally not as accurate
AWS and CSA
Penetration and burn - off rate of the electrode

41. How many times per second does short circuiting take place?
Aluminum wire
DCEP (Direct Current Electrode Positive) Reverse Polarity
Controls the rate of flow of a shielding gas to the gun nozzle
20 to 200 times per second

42. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
85%
Controls the rate of flow of a shielding gas to the gun nozzle
Minutes of elapsed time continually run (out of 10 minutes)
If you dont know this check your phone

43. What type of power source is used with a constant speed wire feeder?
Penetration and burn - off rate of the electrode
Constant voltage (CV)
Wire feed speed
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

44. What 2 controls are found on a GMAW set- up?
Puddle fluidity
Wire feed speed - Voltage control
Minutes of elapsed time continually run (out of 10 minutes)
Speed of the feed motor and - starting / stopping electrode feed

45. What does the term GMAW identify?
Voltage is the force that overcomes resistance to allow amperage flow
Gas metal arc welding
To prevent drawing of liquid CO2 (Carbon Dioxide)
The Arc voltage

46. 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
Minimum distortion due to low heat input
DCEP (Direct Current Electrode Positive) Reverse Polarity
Flux cored wires

47. List the factors that determine the mode of metal transfer
Aluminum wire
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Constant- speed wire feeders and Voltage- sennsing wire feeders

48. List 3 wire drive systems and give a short description of each
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
Constant current (CC)
The Arc voltage
Spatter problems and poor weld appearance

49. In the GMAW process what does amperage control?
Minutes of elapsed time continually run (out of 10 minutes)
Duty cycle
Wire feed speed
Penetration and burn - off rate of the electrode

50. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Penetration and burn - off rate of the electrode
Cause flaking - which can clog the liner and contact tube
Controls the rate of flow of a shielding gas to the gun nozzle
Constant current (CC)