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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 maximum distance that hard wire can be successfully pushed?
Puddle fluidity
3
To prevent drawing of liquid CO2 (Carbon Dioxide)
15 feet (4.5 meters)

2. A pull type drive system is usually used on what type of material?
National Electrical Manufactures Association
By there current carrying capacity
Aluminum wire
Welding process that joins metals by heating them with an electric arc

3. Give a description of 'pinch effect'
Controls the rate of flow of a shielding gas to the gun nozzle
Gas metal arc welding
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
To prevent leakage - Carbon Dioxide (CO2)

4. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Guns
SMAW - GTAW
Higher 26 to 35 arc volts
Shielding the molten weld metal from atmospheric contamination

5. What controls amperage when using GMAW?
To prevent leakage - Carbon Dioxide (CO2)
1/4 inch to 1/2 inch
Wire feed speed
Minimum distortion due to low heat input

6. What does the term GMAW identify?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Gas metal arc welding
...
12 to 22 arc volts

7. List 3 forms compressed gases may be supplied for welding
DCEP (Direct Current Electrode Positive) Reverse Polarity
Cause flaking - which can clog the liner and contact tube
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

8. Give a brief description of the GMAW process
The resistace to electrical current flow increases with it. Causing the electrode to heat
Constant voltage (CV)
Guns
Welding process that joins metals by heating them with an electric arc

9. What happens when the electrode extension is increased?
Voltage is the force that overcomes resistance to allow amperage flow
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Wire feed speed - Voltage control
The resistace to electrical current flow increases with it. Causing the electrode to heat

10. What 2 controls are found on a GMAW set- up?
Constant voltage (CV)
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Wire feed speed - Voltage control
1/4 inch to 1/2 inch

11. A 10 minute cycle of welding time vs cooling time a given machine can handle.
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1/4 inch to 1/2 inch
Duty cycle
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

12. 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
Gives arc voltage values to the control system of the feeder
Welding process that joins metals by heating them with an electric arc
Speed of the feed motor and - starting / stopping electrode feed

13. What is the purpose of the shielding gas used in GMAW?
SMAW - GTAW
To limit the short circuiting current so that spatter is reduced
Puddle fluidity
Shielding the molten weld metal from atmospheric contamination

14. When is the metal transferred with short circuit transfer?
National Electrical Manufactures Association
...
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
When the filler wire is in direct contract with the base metal

15. What type of power source is used with a constant speed wire 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
SMAW - GTAW
Gives arc voltage values to the control system of the feeder
Constant voltage (CV)

16. What 2 organizations designate specifications for GMAW wires?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
AWS and CSA
Duty cycle
Pressure vessels and the piping industry

17. With straight polarity where is 2/3 of the arc energy?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Flux cored wires
The negative side of a welding unit
12 to 22 arc volts

18. Draw a typical volt amp curve for a machine that is designed for GMAW
To prevent drawing of liquid CO2 (Carbon Dioxide)
If you dont know this check your phone
Controls the rate of flow of a shielding gas to the gun nozzle
Reducing the gas source pressure to a constant working pressure

19. What does a flowmeter do and what does it measure?
Guns
Dry ice can form within the flow control openings and cause blockage of shielding gas
Controls the rate of flow of a shielding gas to the gun nozzle
Voltage is the force that overcomes resistance to allow amperage flow

20. How are GMAW guns rated?
Shielding the molten weld metal from atmospheric contamination
12 to 22 arc volts
By there current carrying capacity
To prevent drawing of liquid CO2 (Carbon Dioxide)

21. What does voltage do in an electrical circuit?
15 feet (4.5 meters)
Voltage is the force that overcomes resistance to allow amperage flow
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

22. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
To prevent leakage - Carbon Dioxide (CO2)
(DCEP) Direct Current Electrode Positive or Reverse polarity
DCEP (Direct Current Electrode Positive) Reverse Polarity

23. Why is a fiber washer required and what cylinder gas requires it?
To prevent leakage - Carbon Dioxide (CO2)
Pressure vessels and the piping industry
Minutes of elapsed time continually run (out of 10 minutes)
(DCEP) Direct Current Electrode Positive or Reverse polarity

24. What is the key advantage of short circuiting transfer?
Minimum distortion due to low heat input
Constant voltage (CV)
To limit the short circuiting current so that spatter is reduced
The time rate of response for the current rise and fall

25. What does the wire feeder control?
The time rate of response for the current rise and fall
Shielding the molten weld metal from atmospheric contamination
(DCEP) Direct Current Electrode Positive or Reverse polarity
Speed of the feed motor and - starting / stopping electrode feed

26. How many times per second does short circuiting take place?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Cause flaking - which can clog the liner and contact tube
20 to 200 times per second
Minutes of elapsed time continually run (out of 10 minutes)

27. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Generally not as accurate
12 to 22 arc volts
Pressure vessels and the piping industry

28. List the three methods of metal transfer with GMAW
These terms are quite restrictive and often technically incorrect
Constant voltage (CV)
Short- circuiting transfer - Globular transfer - Spray transfer
Cause flaking - which can clog the liner and contact tube

29. What type of power source is commonly used with a voltage sensing wire feeder?
Dry ice can form within the flow control openings and cause blockage of shielding gas
Constant current (CC)
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Pressure - The rate of flow of a shielding gas

30. List several industries that would use GMAW
Pressure vessels and the piping industry
Spatter problems and poor weld appearance
Cause flaking - which can clog the liner and contact tube
Wire feed speed - Voltage control

31. List the basic equipment requirements for the GMAW process
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Gives arc voltage values to the control system of the feeder
...
The resistace to electrical current flow increases with it. Causing the electrode to heat

32. Why is the term GMAW preferred over MIG or MAG?
The negative side of a welding unit
Reducing the gas source pressure to a constant working pressure
...
These terms are quite restrictive and often technically incorrect

33. List the factors that determine the mode of metal transfer
Higher 26 to 35 arc volts
Short- circuiting transfer - Globular transfer - Spray transfer
Penetration and burn - off rate of the electrode
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

34. In the GMAW process what does amperage control?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Penetration and burn - off rate of the electrode
Controls the rate of flow of a shielding gas to the gun nozzle
AWS and CSA

35. 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
Shielding the molten weld metal from atmospheric contamination
If you dont know this check your phone
Minutes of elapsed time continually run (out of 10 minutes)

36. Why is globular transfer generally avoided with GMAW?
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
Spatter problems and poor weld appearance
The Arc voltage

37. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
85%
Guns
(DCEP) Direct Current Electrode Positive or Reverse polarity
AWS and CSA

38. What would be an indication that the drive roll pressure is adjusted correctly?
V groove or U groove
1/4 inch to 1/2 inch
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Cause flaking - which can clog the liner and contact tube

39. 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
Generally not as accurate
3
Guns

40. What is the main purpose of 'slope'?
To limit the short circuiting current so that spatter is reduced
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
The time rate of response for the current rise and fall
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

41. What is a typical flow rate of CO2 for short circuit transfer?
Gives arc voltage values to the control system of the feeder
Welding process that joins metals by heating them with an electric arc
5.8 to 12.5 L/min
Voltage is the force that overcomes resistance to allow amperage flow

42. What current and polarity is generally used with GMAW?
Puddle fluidity
DCEP (Direct Current Electrode Positive) Reverse Polarity
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

43. What controls the wire speed on a voltage sensing wire feeder?
The Arc voltage
85%
Cause flaking - which can clog the liner and contact tube
By there current carrying capacity

44. Why is a line heater required when using GMAW?
V groove or U groove
Short- circuiting transfer - Globular transfer - Spray transfer
Pressure vessels and the piping industry
Dry ice can form within the flow control openings and cause blockage of shielding gas

45. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
...
Penetration and burn - off rate of the electrode
AWS and CSA
If you dont know this check your phone

46. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Voltage is the force that overcomes resistance to allow amperage flow
Aluminum wire
Gives arc voltage values to the control system of the feeder
When the filler wire is in direct contract with the base metal

47. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
85%
Controls the rate of flow of a shielding gas to the gun nozzle
3
Puddle fluidity

48. In the GMAW process what does voltage control?
Pressure vessels and the piping industry
Puddle fluidity
Constant current (CC)
1/4 inch to 1/2 inch

49. What does the abbreviation NEMA stand for?
National Electrical Manufactures Association
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
1/4 inch to 1/2 inch

50. What processes are constant current (CC) power sources designed to be used with?
Insufficient current to melt the wire off cleanly
Dry ice can form within the flow control openings and cause blockage of shielding gas
SMAW - GTAW
Constant- speed wire feeders and Voltage- sennsing wire feeders