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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 several industries that would use GMAW
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Pressure vessels and the piping industry
To prevent drawing of liquid CO2 (Carbon Dioxide)
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2. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
Spatter problems and poor weld appearance
20 to 200 times per second
Duty cycle
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3. What controls the wire speed on a voltage sensing wire feeder?
The Arc voltage
The resistace to electrical current flow increases with it. Causing the electrode to heat
Short- circuiting transfer - Globular transfer - Spray transfer
Wire feed speed - Voltage control

4. 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
The negative side of a welding unit
Dry ice can form within the flow control openings and cause blockage of shielding gas
20 to 200 times per second

5. What does the abbreviation NEMA stand for?
Generally not as accurate
Gives arc voltage values to the control system of the feeder
National Electrical Manufactures Association
To prevent leakage - Carbon Dioxide (CO2)

6. What is the required arc voltage used for short circuit transfer?
The time rate of response for the current rise and fall
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
To prevent leakage - Carbon Dioxide (CO2)
12 to 22 arc volts

7. What is the effect of too much slope?
Minimum distortion due to low heat input
Controls the rate of flow of a shielding gas to the gun nozzle
Insufficient current to melt the wire off cleanly
To prevent drawing of liquid CO2 (Carbon Dioxide)

8. Regulators control_____________ flowmeters SHOW____________.
Pressure - The rate of flow of a shielding gas
Guns
Gas metal arc welding
Generally not as accurate

9. What output on the welding machine is used to rate the duty cycle?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
15 feet (4.5 meters)
To prevent drawing of liquid CO2 (Carbon Dioxide)
Minutes of elapsed time continually run (out of 10 minutes)

10. What does the wire feeder control?
Speed of the feed motor and - starting / stopping electrode feed
When the filler wire is in direct contract with the base metal
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Spatter problems and poor weld appearance

11. How many times per second does short circuiting take place?
20 to 200 times per second
Reducing the gas source pressure to a constant working pressure
Pressure - The rate of flow of a shielding gas
Duty cycle

12. In the GMAW process what does amperage control?
5.8 to 12.5 L/min
To prevent leakage - Carbon Dioxide (CO2)
Penetration and burn - off rate of the electrode
Constant current (CC)

13. List the basic equipment requirements for the GMAW process
By there current carrying capacity
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Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
When the filler wire is in direct contract with the base metal

14. What 2 controls are found on a GMAW set- up?
Spatter problems and poor weld appearance
To prevent leakage - Carbon Dioxide (CO2)
Wire feed speed - Voltage control
Speed of the feed motor and - starting / stopping electrode feed

15. What does the term GMAW identify?
The negative side of a welding unit
Dry ice can form within the flow control openings and cause blockage of shielding gas
20 to 200 times per second
Gas metal arc welding

16. Why is the term GMAW preferred over MIG or MAG?
These terms are quite restrictive and often technically incorrect
3
15 feet (4.5 meters)
Wire feed speed - Voltage control

17. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
The Arc voltage
Cause flaking - which can clog the liner and contact tube
These terms are quite restrictive and often technically incorrect
3

18. Why is a fiber washer required and what cylinder gas requires it?
Wire feed speed - Voltage control
The time rate of response for the current rise and fall
Speed of the feed motor and - starting / stopping electrode feed
To prevent leakage - Carbon Dioxide (CO2)

19. What is the maximum distance that hard wire can be successfully pushed?
The Arc voltage
15 feet (4.5 meters)
SMAW - GTAW
1/4 inch to 1/2 inch

20. What is a typical flow rate of CO2 for short circuit transfer?
Wire feed speed - Voltage control
5.8 to 12.5 L/min
Short- circuiting transfer - Globular transfer - Spray transfer
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

21. What would be an indication that the drive roll pressure is adjusted correctly?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Voltage is the force that overcomes resistance to allow amperage flow
When the filler wire is in direct contract with the base metal

22. List the factors that determine the mode of metal transfer
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Guns
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

23. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
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Higher 26 to 35 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
Gas metal arc welding

24. Why must CO2 cylinders be used in the vertical position?
To prevent drawing of liquid CO2 (Carbon Dioxide)
Minimum distortion due to low heat input
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Duty cycle

25. What does a flowmeter do and what does it measure?
Controls the rate of flow of a shielding gas to the gun nozzle
Pressure - The rate of flow of a shielding gas
Short- circuiting transfer - Globular transfer - Spray transfer
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

26. Draw a typical volt amp curve for a machine that is designed for GMAW
3
If you dont know this check your phone
Wire feed speed
Minimum distortion due to low heat input

27. What is an advantage of pulsed arc transfer with GMAW?
To prevent leakage - Carbon Dioxide (CO2)
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
If you dont know this check your phone

28. Why is a line heater required when using GMAW?
Dry ice can form within the flow control openings and cause blockage of shielding gas
(DCEP) Direct Current Electrode Positive or Reverse polarity
Constant voltage (CV)
Cause flaking - which can clog the liner and contact tube

29. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Wire feed speed
DCEP (Direct Current Electrode Positive) Reverse Polarity
Motor driven generators - Transformer rectifiers - and Inverter designs
Gives arc voltage values to the control system of the feeder

30. What is the preferred drive roll design for solid wires?
V groove or U groove
Aluminum wire
12 to 22 arc volts
Speed of the feed motor and - starting / stopping electrode feed

31. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
To prevent drawing of liquid CO2 (Carbon Dioxide)
(DCEP) Direct Current Electrode Positive or Reverse polarity
Wire feed speed - Voltage control
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

32. What is the main purpose of 'slope'?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
To limit the short circuiting current so that spatter is reduced
Aluminum wire
Reducing the gas source pressure to a constant working pressure

33. Give a brief description of the GMAW process
Voltage is the force that overcomes resistance to allow amperage flow
The resistace to electrical current flow increases with it. Causing the electrode to heat
Welding process that joins metals by heating them with an electric arc
...

34. List 3 wire drive systems and give a short description of each
Guns
12 to 22 arc volts
To prevent leakage - Carbon Dioxide (CO2)
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

35. What happens when the electrode extension is increased?
Reducing the gas source pressure to a constant working pressure
1/4 inch to 1/2 inch
The resistace to electrical current flow increases with it. Causing the electrode to heat
By there current carrying capacity

36. When is the metal transferred with short circuit transfer?
These terms are quite restrictive and often technically incorrect
By there current carrying capacity
Controls the rate of flow of a shielding gas to the gun nozzle
When the filler wire is in direct contract with the base metal

37. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
DCEP (Direct Current Electrode Positive) Reverse Polarity
...
Speed of the feed motor and - starting / stopping electrode feed

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

39. What controls amperage when using GMAW?
Short- circuiting transfer - Globular transfer - Spray transfer
Controls the rate of flow of a shielding gas to the gun nozzle
1/4 inch to 1/2 inch
Wire feed speed

40. List the three methods of metal transfer with GMAW
Cause flaking - which can clog the liner and contact tube
If you dont know this check your phone
Wire feed speed
Short- circuiting transfer - Globular transfer - Spray transfer

41. How are GMAW guns rated?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Constant voltage (CV)
These terms are quite restrictive and often technically incorrect
By there current carrying capacity

42. What type of power source is used with a constant speed wire feeder?
Constant voltage (CV)
3
The negative side of a welding unit
5.8 to 12.5 L/min

43. What effect does increasing and decreasing the inductance have on the weld?
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
20 to 200 times per second
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

44. In the GMAW process what does voltage control?
The Arc voltage
Puddle fluidity
Insufficient current to melt the wire off cleanly
Minutes of elapsed time continually run (out of 10 minutes)

45. A 10 minute cycle of welding time vs cooling time a given machine can handle.
SMAW - GTAW
Duty cycle
Speed of the feed motor and - starting / stopping electrode feed
Insufficient current to melt the wire off cleanly

46. What does inductance control?
Cause flaking - which can clog the liner and contact tube
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
The time rate of response for the current rise and fall

47. 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
The Arc voltage
Welding process that joins metals by heating them with an electric arc
Pressure vessels and the piping industry

48. What is the key advantage of short circuiting transfer?
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
Generally not as accurate
V groove or U groove

49. What is a solenoid valve and what actuates it?
When the filler wire is in direct contract with the base metal
National Electrical Manufactures Association
Constant- speed wire feeders and Voltage- sennsing wire feeders
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

50. What is another term for electrode holders for GMAW?
Aluminum wire
To prevent leakage - Carbon Dioxide (CO2)
3
Guns