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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.
Don't refresh. All questions and answers are randomly picked and ordered every time you load a test.

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. In the GMAW process what does amperage control?
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Penetration and burn - off rate of the electrode
When the filler wire is in direct contract with the base metal
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

2. Why is the term GMAW preferred over MIG or MAG?
These terms are quite restrictive and often technically incorrect
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Guns
20 to 200 times per second

3. What does a flowmeter do and what does it measure?
Duty cycle
Controls the rate of flow of a shielding gas to the gun nozzle
...
Aluminum wire

4. What is the main purpose of 'slope'?
Penetration and burn - off rate of the electrode
Constant voltage (CV)
To limit the short circuiting current so that spatter is reduced
The resistace to electrical current flow increases with it. Causing the electrode to heat

5. What is the maximum distance that hard wire can be successfully pushed?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Gas metal arc welding
Constant current (CC)
15 feet (4.5 meters)

6. In the GMAW process what does voltage control?
Penetration and burn - off rate of the electrode
Puddle fluidity
Higher 26 to 35 arc volts
Flux cored wires

7. Draw a typical volt amp curve for a machine that is designed for GMAW
To prevent leakage - Carbon Dioxide (CO2)
Wire feed speed - Voltage control
Reducing the gas source pressure to a constant working pressure
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8. List the basic equipment requirements for the GMAW process
The Arc voltage
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
Pressure - The rate of flow of a shielding gas

9. What does voltage do in an electrical circuit?
Voltage is the force that overcomes resistance to allow amperage flow
Pressure vessels and the piping industry
The negative side of a welding unit
The time rate of response for the current rise and fall

10. List 3 wire drive systems and give a short description of each
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15 feet (4.5 meters)
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
85%

11. List the three methods of metal transfer with GMAW
12 to 22 arc volts
Spatter problems and poor weld appearance
To limit the short circuiting current so that spatter is reduced
Short- circuiting transfer - Globular transfer - Spray transfer

12. How many times per second does short circuiting take place?
Cause flaking - which can clog the liner and contact tube
3
20 to 200 times per second
The time rate of response for the current rise and fall

13. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Duty cycle
Spatter problems and poor weld appearance
AWS and CSA
Generally not as accurate

14. What does the abbreviation NEMA stand for?
National Electrical Manufactures Association
Cause flaking - which can clog the liner and contact tube
To limit the short circuiting current so that spatter is reduced
Dry ice can form within the flow control openings and cause blockage of shielding gas

15. 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
Insufficient current to melt the wire off cleanly
Penetration and burn - off rate of the electrode
By there current carrying capacity

16. Why must CO2 cylinders be used in the vertical position?
Pressure - The rate of flow of a shielding gas
Flux cored wires
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
To prevent drawing of liquid CO2 (Carbon Dioxide)

17. List 3 forms compressed gases may be supplied for welding
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
To prevent drawing of liquid CO2 (Carbon Dioxide)
Gas metal arc welding
Speed of the feed motor and - starting / stopping electrode feed

18. When is the metal transferred with short circuit transfer?
Constant- speed wire feeders and Voltage- sennsing wire feeders
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
These terms are quite restrictive and often technically incorrect

19. What type of power source is commonly used with a voltage sensing wire feeder?
Constant current (CC)
Aluminum wire
National Electrical Manufactures Association
5.8 to 12.5 L/min

20. What controls the wire speed on a voltage sensing wire feeder?
The Arc voltage
Pressure vessels and the piping industry
Constant current (CC)
Motor driven generators - Transformer rectifiers - and Inverter designs

21. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Pressure vessels and the piping industry
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Duty cycle
Motor driven generators - Transformer rectifiers - and Inverter designs

22. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
Guns
When the filler wire is in direct contract with the base metal
SMAW - GTAW
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23. What is a typical flow rate of CO2 for short circuit transfer?
Constant voltage (CV)
5.8 to 12.5 L/min
Pressure vessels and the piping industry
1/4 inch to 1/2 inch

24. Regulators control_____________ flowmeters SHOW____________.
Pressure - The rate of flow of a shielding gas
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
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

25. What processes are constant current (CC) power sources designed to be used with?
SMAW - GTAW
Gives arc voltage values to the control system of the feeder
Insufficient current to melt the wire off cleanly
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

26. What controls amperage when using GMAW?
Minimum distortion due to low heat input
Voltage is the force that overcomes resistance to allow amperage flow
Wire feed speed
Minutes of elapsed time continually run (out of 10 minutes)

27. What is another term for electrode holders for GMAW?
Gives arc voltage values to the control system of the feeder
Pressure vessels and the piping industry
Guns
Generally not as accurate

28. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
85%
By there current carrying capacity
Dry ice can form within the flow control openings and cause blockage of shielding gas
Reducing the gas source pressure to a constant working pressure

29. List the factors that determine the mode of metal transfer
Minutes of elapsed time continually run (out of 10 minutes)
Higher 26 to 35 arc volts
85%
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

30. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Pressure - The rate of flow of a shielding gas
If you dont know this check your phone
Gives arc voltage values to the control system of the feeder
Controls the rate of flow of a shielding gas to the gun nozzle

31. Why is a fiber washer required and what cylinder gas requires it?
To prevent leakage - Carbon Dioxide (CO2)
Constant current (CC)
Cause flaking - which can clog the liner and contact tube
Wire feed speed

32. Give a brief description of the GMAW process
Welding process that joins metals by heating them with an electric arc
1/4 inch to 1/2 inch
Gives arc voltage values to the control system of the feeder
Generally not as accurate

33. What output on the welding machine is used to rate the duty cycle?
Minutes of elapsed time continually run (out of 10 minutes)
Guns
85%
5.8 to 12.5 L/min

34. List several industries that would use GMAW
To limit the short circuiting current so that spatter is reduced
Motor driven generators - Transformer rectifiers - and Inverter designs
Spatter problems and poor weld appearance
Pressure vessels and the piping industry

35. What wire are knurled drive rolls most commonly used on?
Gas metal arc welding
15 feet (4.5 meters)
Flux cored wires
Insufficient current to melt the wire off cleanly

36. What is an advantage of pulsed arc transfer with GMAW?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
When the filler wire is in direct contract with the base metal
3
Puddle fluidity

37. What would be an indication that the drive roll pressure is adjusted correctly?
1/4 inch to 1/2 inch
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Shielding the molten weld metal from atmospheric contamination
To limit the short circuiting current so that spatter is reduced

38. What are the 2 types of wire feeders available?
Constant voltage (CV)
Constant- speed wire feeders and Voltage- sennsing wire feeders
Puddle fluidity
When the filler wire is in direct contract with the base metal

39. With straight polarity where is 2/3 of the arc energy?
Cause flaking - which can clog the liner and contact tube
The negative side of a welding unit
3
Pressure vessels and the piping industry

40. 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
If you dont know this check your phone
Aluminum wire
The Arc voltage

41. What type of power source is used with a constant speed wire feeder?
Welding process that joins metals by heating them with an electric arc
Generally not as accurate
Constant voltage (CV)
85%

42. What is the required arc voltage used for short circuit transfer?
12 to 22 arc volts
5.8 to 12.5 L/min
Puddle fluidity
Wire feed speed - Voltage control

43. What does the term GMAW identify?
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Generally not as accurate
Gas metal arc welding
Wire feed speed - Voltage control

44. What is a solenoid valve and what actuates it?
By there current carrying capacity
Dry ice can form within the flow control openings and cause blockage of shielding gas
If you dont know this check your phone
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

45. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
Controls the rate of flow of a shielding gas to the gun nozzle
3
AWS and CSA
These terms are quite restrictive and often technically incorrect

46. Why is a line heater required when using GMAW?
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
Dry ice can form within the flow control openings and cause blockage of shielding gas
Flux cored wires

47. Why is globular transfer generally avoided with GMAW?
Wire feed speed
85%
Voltage is the force that overcomes resistance to allow amperage flow
Spatter problems and poor weld appearance

48. What current and polarity is generally used with GMAW?
Wire feed speed
Shielding the molten weld metal from atmospheric contamination
If you dont know this check your phone
DCEP (Direct Current Electrode Positive) Reverse Polarity

49. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
V groove or U groove
The negative side of a welding unit
Minutes of elapsed time continually run (out of 10 minutes)
Cause flaking - which can clog the liner and contact tube

50. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Controls the rate of flow of a shielding gas to the gun nozzle
Higher 26 to 35 arc volts
15 feet (4.5 meters)
20 to 200 times per second