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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. How are GMAW guns rated?
Penetration and burn - off rate of the electrode
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
AWS and CSA
By there current carrying capacity

2. What does a flowmeter do and what does it measure?
12 to 22 arc volts
Controls the rate of flow of a shielding gas to the gun nozzle
Higher 26 to 35 arc volts
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

3. What type of power source is commonly used with a voltage sensing wire feeder?
If you dont know this check your phone
3
Constant current (CC)
DCEP (Direct Current Electrode Positive) Reverse Polarity

4. What are the 2 types of wire feeders available?
Duty cycle
Constant- speed wire feeders and Voltage- sennsing wire feeders
5.8 to 12.5 L/min
Shielding the molten weld metal from atmospheric contamination

5. 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
Welding process that joins metals by heating them with an electric arc
Constant voltage (CV)
Dry ice can form within the flow control openings and cause blockage of shielding gas

6. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
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
Cause flaking - which can clog the liner and contact tube
Controls the rate of flow of a shielding gas to the gun nozzle
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7. What is a solenoid valve and what actuates it?
To prevent drawing of liquid CO2 (Carbon Dioxide)
Motor driven generators - Transformer rectifiers - and Inverter designs
By there current carrying capacity
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

8. A 10 minute cycle of welding time vs cooling time a given machine can handle.
The negative side of a welding unit
Minutes of elapsed time continually run (out of 10 minutes)
Duty cycle
(DCEP) Direct Current Electrode Positive or Reverse polarity

9. What is the maximum distance that hard wire can be successfully pushed?
15 feet (4.5 meters)
...
Insufficient current to melt the wire off cleanly
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10. List the basic equipment requirements for 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
SMAW - GTAW
Controls the rate of flow of a shielding gas to the gun nozzle
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

11. With straight polarity where is 2/3 of the arc energy?
Gas metal arc welding
The negative side of a welding unit
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Wire feed speed - Voltage control

12. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
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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
1/4 inch to 1/2 inch
Controls the rate of flow of a shielding gas to the gun nozzle

13. What current and polarity is generally used with GMAW?
By there current carrying capacity
3
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
DCEP (Direct Current Electrode Positive) Reverse Polarity

14. What is a typical flow rate of CO2 for short circuit transfer?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
12 to 22 arc volts
5.8 to 12.5 L/min
Guns

15. What happens when the electrode extension is increased?
DCEP (Direct Current Electrode Positive) Reverse Polarity
These terms are quite restrictive and often technically incorrect
The resistace to electrical current flow increases with it. Causing the electrode to heat
12 to 22 arc volts

16. Give a description of 'pinch effect'
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
Welding process that joins metals by heating them with an electric arc
Wire feed speed - Voltage control

17. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
Flux cored wires
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
...
15 feet (4.5 meters)

18. Why is a line heater required when using GMAW?
Wire feed speed
Welding process that joins metals by heating them with an electric arc
When the filler wire is in direct contract with the base metal
Dry ice can form within the flow control openings and cause blockage of shielding gas

19. List 3 forms compressed gases may be supplied for welding
Guns
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Shielding the molten weld metal from atmospheric contamination

20. Why is globular transfer generally avoided with GMAW?
Guns
5.8 to 12.5 L/min
Cause flaking - which can clog the liner and contact tube
Spatter problems and poor weld appearance

21. Regulators control_____________ flowmeters SHOW____________.
Cause flaking - which can clog the liner and contact tube
Dry ice can form within the flow control openings and cause blockage of shielding gas
Pressure - The rate of flow of a shielding gas
Short- circuiting transfer - Globular transfer - Spray transfer

22. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Speed of the feed motor and - starting / stopping electrode feed
Pressure - The rate of flow of a shielding gas
To limit the short circuiting current so that spatter is reduced
Generally not as accurate

23. What type of power source is used with a constant speed wire feeder?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Gas metal arc welding
Constant voltage (CV)
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24. Why is the term GMAW preferred over MIG or MAG?
To limit the short circuiting current so that spatter is reduced
Guns
By there current carrying capacity
These terms are quite restrictive and often technically incorrect

25. What is the effect of too much slope?
Insufficient current to melt the wire off cleanly
To prevent drawing of liquid CO2 (Carbon Dioxide)
Shielding the molten weld metal from atmospheric contamination
The negative side of a welding unit

26. In the GMAW process what does voltage control?
Puddle fluidity
Minimum distortion due to low heat input
Controls the rate of flow of a shielding gas to the gun nozzle
Gas metal arc welding

27. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
DCEP (Direct Current Electrode Positive) Reverse Polarity
(DCEP) Direct Current Electrode Positive or Reverse polarity
Higher 26 to 35 arc volts
20 to 200 times per second

28. 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
Flux cored wires
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

29. List the three methods of metal transfer with GMAW
DCEP (Direct Current Electrode Positive) Reverse Polarity
AWS and CSA
If you dont know this check your phone
Short- circuiting transfer - Globular transfer - Spray transfer

30. What 2 controls are found on a GMAW set- up?
...
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Shielding the molten weld metal from atmospheric contamination
Wire feed speed - Voltage control

31. What effect does increasing and decreasing the inductance have on the weld?
15 feet (4.5 meters)
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
National Electrical Manufactures Association
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

32. List the factors that determine the mode of metal transfer
15 feet (4.5 meters)
Reducing the gas source pressure to a constant working pressure
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Pressure vessels and the piping industry

33. What does voltage do in an electrical circuit?
Voltage is the force that overcomes resistance to allow amperage flow
Wire feed speed
Cause flaking - which can clog the liner and contact tube
If you dont know this check your phone

34. When is the metal transferred with short circuit transfer?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
When the filler wire is in direct contract with the base metal
The resistace to electrical current flow increases with it. Causing the electrode to heat
Minutes of elapsed time continually run (out of 10 minutes)

35. What is the key advantage of short circuiting transfer?
Minimum distortion due to low heat input
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Dry ice can form within the flow control openings and cause blockage of shielding gas
Aluminum wire

36. What is the preferred drive roll design for solid wires?
Speed of the feed motor and - starting / stopping electrode feed
V groove or U groove
The negative side of a welding unit
Gives arc voltage values to the control system of the feeder

37. What does inductance control?
The time rate of response for the current rise and fall
By there current carrying capacity
Minutes of elapsed time continually run (out of 10 minutes)
DCEP (Direct Current Electrode Positive) Reverse Polarity

38. Draw a typical volt amp curve for a machine that is designed for GMAW
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Shielding the molten weld metal from atmospheric contamination
If you dont know this check your phone
85%

39. What is the main purpose of 'slope'?
Higher 26 to 35 arc volts
Dry ice can form within the flow control openings and cause blockage of shielding gas
Flux cored wires
To limit the short circuiting current so that spatter is reduced

40. Why must CO2 cylinders be used in the vertical position?
The time rate of response for the current rise and fall
To prevent drawing of liquid CO2 (Carbon Dioxide)
AWS and CSA
Flux cored wires

41. What is another term for electrode holders for GMAW?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Gas metal arc welding
5.8 to 12.5 L/min
Guns

42. What is the required arc voltage used for short circuit transfer?
Wire feed speed
12 to 22 arc volts
Generally not as accurate
If you dont know this check your phone

43. What is the purpose of the shielding gas used in GMAW?
Shielding the molten weld metal from atmospheric contamination
5.8 to 12.5 L/min
Puddle fluidity
National Electrical Manufactures Association

44. What processes are constant current (CC) power sources designed to be used with?
12 to 22 arc volts
Flux cored wires
SMAW - GTAW
Minimum distortion due to low heat input

45. What 2 organizations designate specifications for GMAW wires?
Wire feed speed
20 to 200 times per second
AWS and CSA
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

46. What wire are knurled drive rolls most commonly used on?
Flux cored wires
To prevent leakage - Carbon Dioxide (CO2)
Pressure - The rate of flow of a shielding gas
Aluminum wire

47. In the GMAW process what does amperage control?
Voltage is the force that overcomes resistance to allow amperage flow
To limit the short circuiting current so that spatter is reduced
1/4 inch to 1/2 inch
Penetration and burn - off rate of the electrode

48. Give a brief description of the GMAW process
The negative side of a welding unit
Insufficient current to melt the wire off cleanly
Welding process that joins metals by heating them with an electric arc
Wire feed speed - Voltage control

49. What controls the wire speed on a voltage sensing wire feeder?
When the filler wire is in direct contract with the base metal
Generally not as accurate
The Arc voltage
National Electrical Manufactures Association

50. What does the term GMAW identify?
1/4 inch to 1/2 inch
Pressure vessels and the piping industry
Gas metal arc welding
To prevent leakage - Carbon Dioxide (CO2)