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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. What does voltage do in an electrical circuit?
Voltage is the force that overcomes resistance to allow amperage flow
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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
Controls the rate of flow of a shielding gas to the gun nozzle

2. Why is a fiber washer required and what cylinder gas requires it?
Gives arc voltage values to the control system of the feeder
Cause flaking - which can clog the liner and contact tube
To prevent leakage - Carbon Dioxide (CO2)
Penetration and burn - off rate of the electrode

3. What happens when the electrode extension is increased?
Flux cored wires
Constant current (CC)
Cause flaking - which can clog the liner and contact tube
The resistace to electrical current flow increases with it. Causing the electrode to heat

4. What is another term for electrode holders for GMAW?
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
Guns
Motor driven generators - Transformer rectifiers - and Inverter designs
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5. A pull type drive system is usually used on what type of material?
Aluminum wire
DCEP (Direct Current Electrode Positive) Reverse Polarity
Gives arc voltage values to the control system of the feeder
Reducing the gas source pressure to a constant working pressure

6. What are the 2 types of wire feeders available?
Constant- speed wire feeders and Voltage- sennsing wire feeders
Pressure - The rate of flow of a shielding gas
(DCEP) Direct Current Electrode Positive or Reverse polarity
Wire feeds smoothly (yet will slip should a problem occur in the gun)

7. What is the required arc voltage used for short circuit transfer?
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85%
Pressure vessels and the piping industry
12 to 22 arc volts

8. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Motor driven generators - Transformer rectifiers - and Inverter designs
By there current carrying capacity
Generally not as accurate
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

9. List several industries that would use GMAW
Pressure vessels and the piping industry
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Aluminum wire
Duty cycle

10. What does the abbreviation NEMA stand for?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
15 feet (4.5 meters)
National Electrical Manufactures Association
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11. List the factors that determine the mode of metal transfer
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Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Generally not as accurate
15 feet (4.5 meters)

12. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
Generally not as accurate
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
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AWS and CSA

13. What is the preferred drive roll design for solid wires?
V groove or U groove
To prevent leakage - Carbon Dioxide (CO2)
20 to 200 times per second
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 reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
The time rate of response for the current rise and fall
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

15. What is the effect of too much slope?
Short- circuiting transfer - Globular transfer - Spray transfer
When the filler wire is in direct contract with the base metal
Generally not as accurate
Insufficient current to melt the wire off cleanly

16. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Minutes of elapsed time continually run (out of 10 minutes)
Cause flaking - which can clog the liner and contact tube
12 to 22 arc volts
Generally not as accurate

17. Give a brief description of the GMAW process
12 to 22 arc volts
Constant current (CC)
Welding process that joins metals by heating them with an electric arc
Gas metal arc welding

18. Why is the term GMAW preferred over MIG or MAG?
These terms are quite restrictive and often technically incorrect
15 feet (4.5 meters)
1/4 inch to 1/2 inch
Shielding the molten weld metal from atmospheric contamination

19. What current and polarity is generally used with GMAW?
Spatter problems and poor weld appearance
DCEP (Direct Current Electrode Positive) Reverse Polarity
Puddle fluidity
The Arc voltage

20. Regulators control_____________ flowmeters SHOW____________.
V groove or U groove
12 to 22 arc volts
1/4 inch to 1/2 inch
Pressure - The rate of flow of a shielding gas

21. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Guns
Constant voltage (CV)
Higher 26 to 35 arc volts
The Arc voltage

22. Give a description of 'pinch effect'
Pressure - The rate of flow of a shielding gas
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
The negative side of a welding unit
Flux cored wires

23. What is the key advantage of short circuiting transfer?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Minimum distortion due to low heat input
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

24. With straight polarity where is 2/3 of the arc energy?
The negative side of a welding unit
Constant voltage (CV)
Wire feed speed
Generally not as accurate

25. What does the term GMAW identify?
20 to 200 times per second
Constant voltage (CV)
Higher 26 to 35 arc volts
Gas metal arc welding

26. What is the recommended electrode stick- out for .035 solid wire?
85%
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
DCEP (Direct Current Electrode Positive) Reverse Polarity
1/4 inch to 1/2 inch

27. What is the purpose of a regulator and what does it indicate on its gauges?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Reducing the gas source pressure to a constant working pressure
12 to 22 arc volts
Guns

28. What output on the welding machine is used to rate the duty cycle?
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Minutes of elapsed time continually run (out of 10 minutes)
Short- circuiting transfer - Globular transfer - Spray transfer
Dry ice can form within the flow control openings and cause blockage of shielding gas

29. What is the purpose of the shielding gas used in GMAW?
Shielding the molten weld metal from atmospheric contamination
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Voltage is the force that overcomes resistance to allow amperage flow
Short- circuiting transfer - Globular transfer - Spray transfer

30. Why must CO2 cylinders be used in the vertical position?
Controls the rate of flow of a shielding gas to the gun nozzle
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Flux cored wires
To prevent drawing of liquid CO2 (Carbon Dioxide)

31. In the GMAW process what does amperage control?
Spatter problems and poor weld appearance
Dry ice can form within the flow control openings and cause blockage of shielding gas
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Penetration and burn - off rate of the electrode

32. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
3
(DCEP) Direct Current Electrode Positive or Reverse polarity
Gives arc voltage values to the control system of the feeder
1/4 inch to 1/2 inch

33. What power sources are used with the GMAW Process?
Dry ice can form within the flow control openings and cause blockage of shielding gas
SMAW - GTAW
Flux cored wires
Motor driven generators - Transformer rectifiers - and Inverter designs

34. What is the main purpose of 'slope'?
Controls the rate of flow of a shielding gas to the gun nozzle
By there current carrying capacity
Pressure - The rate of flow of a shielding gas
To limit the short circuiting current so that spatter is reduced

35. List 3 forms compressed gases may be supplied for welding
Cause flaking - which can clog the liner and contact tube
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
V groove or U groove
Penetration and burn - off rate of the electrode

36. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
85%
1/4 inch to 1/2 inch
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
15 feet (4.5 meters)

37. In the GMAW process what does voltage control?
Puddle fluidity
By there current carrying capacity
Guns
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

38. What effect does increasing and decreasing the inductance have on the weld?
Constant current (CC)
5.8 to 12.5 L/min
The Arc voltage
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

39. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
Reducing the gas source pressure to a constant working pressure
Guns
Wire feed speed - Voltage control
(DCEP) Direct Current Electrode Positive or Reverse polarity

40. What wire are knurled drive rolls most commonly used on?
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
V groove or U groove
Flux cored wires
Speed of the feed motor and - starting / stopping electrode feed

41. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Duty cycle
Controls the rate of flow of a shielding gas to the gun nozzle
Shielding the molten weld metal from atmospheric contamination
12 to 22 arc volts

42. What would be an indication that the drive roll pressure is adjusted correctly?
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
These terms are quite restrictive and often technically incorrect
Constant- speed wire feeders and Voltage- sennsing wire feeders
Wire feeds smoothly (yet will slip should a problem occur in the gun)

43. What does a flowmeter do and what does it measure?
If you dont know this check your phone
Controls the rate of flow of a shielding gas to the gun nozzle
Wire feed speed - Voltage control
The time rate of response for the current rise and fall

44. When is the metal transferred with short circuit transfer?
Spatter problems and poor weld appearance
The negative side of a welding unit
When the filler wire is in direct contract with the base metal
Controls the rate of flow of a shielding gas to the gun nozzle

45. How many times per second does short circuiting take place?
Flux cored wires
By there current carrying capacity
20 to 200 times per second
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

46. What does inductance control?
Minutes of elapsed time continually run (out of 10 minutes)
To limit the short circuiting current so that spatter is reduced
The time rate of response for the current rise and fall
Spatter problems and poor weld appearance

47. Draw a typical volt amp curve for a machine that is designed for GMAW
Dry ice can form within the flow control openings and cause blockage of shielding gas
If you dont know this check your phone
To limit the short circuiting current so that spatter is reduced
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

48. What is a typical flow rate of CO2 for short circuit transfer?
5.8 to 12.5 L/min
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
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

49. What processes are constant current (CC) power sources designed to be used with?
SMAW - GTAW
Minimum distortion due to low heat input
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

50. List 3 wire drive systems and give a short description of each
Controls the rate of flow of a shielding gas to the gun nozzle
Constant current (CC)
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
Generally not as accurate