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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 output on the welding machine is used to rate the duty cycle?
Gives arc voltage values to the control system of the feeder
When the filler wire is in direct contract with the base metal
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)

2. List the basic equipment requirements for the GMAW process
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
National Electrical Manufactures Association
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Duty cycle

3. What is the purpose of the shielding gas used in GMAW?
Shielding the molten weld metal from atmospheric contamination
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
5.8 to 12.5 L/min

4. Why must CO2 cylinders be used in the vertical position?
Minutes of elapsed time continually run (out of 10 minutes)
V groove or U groove
AWS and CSA
To prevent drawing of liquid CO2 (Carbon Dioxide)

5. What is the recommended electrode stick- out for .035 solid wire?
Penetration and burn - off rate of the electrode
The negative side of a welding unit
1/4 inch to 1/2 inch
Gas metal arc welding

6. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
The time rate of response for the current rise and fall
1/4 inch to 1/2 inch
Gives arc voltage values to the control system of the feeder
Reducing the gas source pressure to a constant working pressure

7. Draw a typical volt amp curve for a machine that is designed for GMAW
Welding process that joins metals by heating them with an electric arc
Minutes of elapsed time continually run (out of 10 minutes)
If you dont know this check your phone
Insufficient current to melt the wire off cleanly

8. What current and polarity is generally used with GMAW?
3
Pressure vessels and the piping industry
DCEP (Direct Current Electrode Positive) Reverse Polarity
Welding process that joins metals by heating them with an electric arc

9. What does a flowmeter do and what does it measure?
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
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Controls the rate of flow of a shielding gas to the gun nozzle

10. How many times per second does short circuiting take place?
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
Pressure vessels and the piping industry
By there current carrying capacity

11. Why is a line heater required when using GMAW?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Dry ice can form within the flow control openings and cause blockage of shielding gas
Pressure - The rate of flow of a shielding gas
15 feet (4.5 meters)

12. Why is a fiber washer required and what cylinder gas requires it?
Pressure vessels and the piping industry
To prevent leakage - Carbon Dioxide (CO2)
Flux cored wires
Insufficient current to melt the wire off cleanly

13. What type of power source is used with a constant speed wire feeder?
AWS and CSA
Constant voltage (CV)
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

14. What is the main purpose of 'slope'?
12 to 22 arc volts
Cause flaking - which can clog the liner and contact tube
To limit the short circuiting current so that spatter is reduced
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

15. What 2 organizations designate specifications for GMAW wires?
AWS and CSA
Reducing the gas source pressure to a constant working pressure
Wire feed speed
SMAW - GTAW

16. What 2 controls are found on a GMAW set- up?
Wire feed speed - Voltage control
1/4 inch to 1/2 inch
Reducing the gas source pressure to a constant working pressure
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

17. What controls the wire speed on a voltage sensing wire feeder?
The resistace to electrical current flow increases with it. Causing the electrode to heat
V groove or U groove
The Arc voltage
Welding process that joins metals by heating them with an electric arc

18. What wire are knurled drive rolls most commonly used on?
Flux cored wires
Guns
Short- circuiting transfer - Globular transfer - Spray transfer
20 to 200 times per second

19. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Higher 26 to 35 arc volts
The resistace to electrical current flow increases with it. Causing the electrode to heat
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

20. What is a solenoid valve and what actuates it?
3
Constant current (CC)
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
If you dont know this check your phone

21. Give a brief description of the GMAW process
1/4 inch to 1/2 inch
SMAW - GTAW
Welding process that joins metals by heating them with an electric arc
Reducing the gas source pressure to a constant working pressure

22. What is the purpose of a regulator and what does it indicate on its gauges?
National Electrical Manufactures Association
Shielding the molten weld metal from atmospheric contamination
Constant voltage (CV)
Reducing the gas source pressure to a constant working pressure

23. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
Insufficient current to melt the wire off cleanly
Welding process that joins metals by heating them with an electric arc
Higher 26 to 35 arc volts
...

24. What type of power source is commonly used with a voltage sensing wire feeder?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Constant current (CC)
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
SMAW - GTAW

25. Regulators control_____________ flowmeters SHOW____________.
To prevent leakage - Carbon Dioxide (CO2)
Aluminum wire
DCEP (Direct Current Electrode Positive) Reverse Polarity
Pressure - The rate of flow of a shielding gas

26. What does the wire feeder control?
To prevent leakage - Carbon Dioxide (CO2)
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Speed of the feed motor and - starting / stopping electrode feed
National Electrical Manufactures Association

27. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
If you dont know this check your phone
Motor driven generators - Transformer rectifiers - and Inverter designs
The resistace to electrical current flow increases with it. Causing the electrode to heat
Duty cycle

28. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
If you dont know this check your phone
3
...

29. List several industries that would use GMAW
Pressure vessels and the piping industry
When the filler wire is in direct contract with the base metal
Penetration and burn - off rate of the electrode
Minimum distortion due to low heat input

30. What does the term GMAW identify?
Wire feed speed - Voltage control
Gas metal arc welding
By there current carrying capacity
To prevent leakage - Carbon Dioxide (CO2)

31. List the factors that determine the mode of metal transfer
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
If you dont know this check your phone
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 limit the short circuiting current so that spatter is reduced

32. What does voltage do in an electrical circuit?
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
Minutes of elapsed time continually run (out of 10 minutes)
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Voltage is the force that overcomes resistance to allow amperage flow

33. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
85%
Constant- speed wire feeders and Voltage- sennsing wire feeders
Spatter problems and poor weld appearance
Penetration and burn - off rate of the electrode

34. Why is the term GMAW preferred over MIG or MAG?
The time rate of response for the current rise and fall
Controls the rate of flow of a shielding gas to the gun nozzle
These terms are quite restrictive and often technically incorrect
Pressure vessels and the piping industry

35. 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
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Wire feed speed - Voltage control
Controls the rate of flow of a shielding gas to the gun nozzle

36. List the three methods of metal transfer with GMAW
Short- circuiting transfer - Globular transfer - Spray transfer
15 feet (4.5 meters)
Minutes of elapsed time continually run (out of 10 minutes)
Minimum distortion due to low heat input

37. 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)
1/4 inch to 1/2 inch
Pressure - The rate of flow of a shielding gas
DCEP (Direct Current Electrode Positive) Reverse Polarity

38. How are GMAW guns rated?
SMAW - GTAW
Welding process that joins metals by heating them with an electric arc
By there current carrying capacity
Pressure - The rate of flow of a shielding gas

39. When is the metal transferred with short circuit transfer?
Constant- speed wire feeders and Voltage- sennsing wire feeders
The time rate of response for the current rise and fall
When the filler wire is in direct contract with the base metal
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

40. What is the required arc voltage used for short circuit transfer?
85%
12 to 22 arc volts
To prevent leakage - Carbon Dioxide (CO2)
National Electrical Manufactures Association

41. What does inductance control?
85%
5.8 to 12.5 L/min
The time rate of response for the current rise and fall
Penetration and burn - off rate of the electrode

42. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Generally not as accurate
Minimum distortion due to low heat input
20 to 200 times per second
3

43. What is the maximum distance that hard wire can be successfully pushed?
Higher 26 to 35 arc volts
5.8 to 12.5 L/min
15 feet (4.5 meters)
Generally not as accurate

44. What power sources are used with the GMAW Process?
Constant voltage (CV)
Motor driven generators - Transformer rectifiers - and Inverter designs
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
15 feet (4.5 meters)

45. What controls amperage when using GMAW?
By there current carrying capacity
Minutes of elapsed time continually run (out of 10 minutes)
Wire feed speed - Voltage control
Wire feed speed

46. What effect does increasing and decreasing the inductance have on the weld?
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
Constant current (CC)
The resistace to electrical current flow increases with it. Causing the electrode to heat

47. What processes are constant current (CC) power sources designed to be used with?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
These terms are quite restrictive and often technically incorrect
SMAW - GTAW
Wire feeds smoothly (yet will slip should a problem occur in the gun)

48. What is an advantage of pulsed arc transfer with GMAW?
Cause flaking - which can clog the liner and contact tube
...
The resistace to electrical current flow increases with it. Causing the electrode to heat
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

49. What is the preferred drive roll design for solid wires?
V groove or U groove
Constant current (CC)
Higher 26 to 35 arc volts
Pressure vessels and the piping industry

50. A pull type drive system is usually used on what type of material?
The resistace to electrical current flow increases with it. Causing the electrode to heat
15 feet (4.5 meters)
5.8 to 12.5 L/min
Aluminum wire