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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 the factors that determine the mode of metal transfer
Wire feed speed - Voltage control
85%
20 to 200 times per second
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

2. What type of power source is commonly used with a voltage sensing wire feeder?
Constant current (CC)
By there current carrying capacity
Aluminum wire
20 to 200 times per second

3. What are the 2 types of wire feeders available?
Minimum distortion due to low heat input
Pressure - The rate of flow of a shielding gas
Duty cycle
Constant- speed wire feeders and Voltage- sennsing wire feeders

4. In the GMAW process what does voltage control?
SMAW - GTAW
Wire feeds smoothly (yet will slip should a problem occur in the gun)
V groove or U groove
Puddle fluidity

5. What is the disadvantage of the gauge preset type of regulator/flowmeter?
5.8 to 12.5 L/min
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Short- circuiting transfer - Globular transfer - Spray transfer
Generally not as accurate

6. What would be an indication that the drive roll pressure is adjusted correctly?
Dry ice can form within the flow control openings and cause blockage of shielding gas
3
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

7. What does voltage do in an electrical circuit?
Voltage is the force that overcomes resistance to allow amperage flow
Constant voltage (CV)
Dry ice can form within the flow control openings and cause blockage of shielding gas
To prevent drawing of liquid CO2 (Carbon Dioxide)

8. What is the maximum distance that hard wire can be successfully pushed?
Penetration and burn - off rate of the electrode
Wire feeds smoothly (yet will slip should a problem occur in the gun)
15 feet (4.5 meters)
AWS and CSA

9. What is the purpose of the shielding gas used in GMAW?
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5.8 to 12.5 L/min
To prevent leakage - Carbon Dioxide (CO2)
Shielding the molten weld metal from atmospheric contamination

10. In the GMAW process what does amperage control?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Insufficient current to melt the wire off cleanly
By there current carrying capacity
Penetration and burn - off rate of the electrode

11. What wire are knurled drive rolls most commonly used on?
Flux cored wires
National Electrical Manufactures Association
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Pressure - The rate of flow of a shielding gas

12. What does inductance control?
DCEP (Direct Current Electrode Positive) Reverse Polarity
By there current carrying capacity
Wire feed speed - Voltage control
The time rate of response for the current rise and fall

13. What controls amperage when using GMAW?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Wire feed speed
Guns
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

14. What does the wire feeder control?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Cause flaking - which can clog the liner and contact tube
Motor driven generators - Transformer rectifiers - and Inverter designs
Speed of the feed motor and - starting / stopping electrode feed

15. Give a description of 'pinch effect'
Minutes of elapsed time continually run (out of 10 minutes)
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Penetration and burn - off rate of the electrode
Constant current (CC)

16. What is another term for electrode holders for GMAW?
Short- circuiting transfer - Globular transfer - Spray transfer
Gas metal arc welding
Guns
SMAW - GTAW

17. 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
Dry ice can form within the flow control openings and cause blockage of shielding gas
Shielding the molten weld metal from atmospheric contamination
These terms are quite restrictive and often technically incorrect

18. Why is a line heater required when using GMAW?
Insufficient current to melt the wire off cleanly
Gas metal arc welding
Dry ice can form within the flow control openings and cause blockage of shielding gas
1/4 inch to 1/2 inch

19. What is a solenoid valve and what actuates it?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Pressure vessels and the piping industry
If you dont know this check your phone
Controls the rate of flow of a shielding gas to the gun nozzle

20. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
SMAW - GTAW
The negative side of a welding unit
V groove or U groove
...

21. What is the purpose of a regulator and what does it indicate on its gauges?
Aluminum wire
Insufficient current to melt the wire off cleanly
Motor driven generators - Transformer rectifiers - and Inverter designs
Reducing the gas source pressure to a constant working pressure

22. List 3 wire drive systems and give a short description of each
20 to 200 times per second
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
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
(DCEP) Direct Current Electrode Positive or Reverse polarity

23. List several industries that would use GMAW
Minutes of elapsed time continually run (out of 10 minutes)
Pressure vessels and the piping industry
Flux cored wires
Higher 26 to 35 arc volts

24. What is the main purpose of 'slope'?
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Controls the rate of flow of a shielding gas to the gun nozzle
Penetration and burn - off rate of the electrode
To limit the short circuiting current so that spatter is reduced

25. What is a typical flow rate of CO2 for short circuit transfer?
5.8 to 12.5 L/min
Constant voltage (CV)
Voltage is the force that overcomes resistance to allow amperage flow
12 to 22 arc volts

26. What is the preferred drive roll design for solid wires?
V groove or U groove
Short- circuiting transfer - Globular transfer - Spray transfer
Wire feed speed
To prevent leakage - Carbon Dioxide (CO2)

27. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
To prevent leakage - Carbon Dioxide (CO2)
(DCEP) Direct Current Electrode Positive or Reverse polarity
Dry ice can form within the flow control openings and cause blockage of shielding gas

28. What type of power source is used with a constant speed wire feeder?
...
Constant voltage (CV)
Gas metal arc welding
AWS and CSA

29. What 2 controls are found on a GMAW set- up?
Wire feed speed - Voltage control
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
...

30. A pull type drive system is usually used on what type of material?
To limit the short circuiting current so that spatter is reduced
Constant voltage (CV)
85%
Aluminum wire

31. What is the key advantage of short circuiting transfer?
Minimum distortion due to low heat input
The Arc voltage
The negative side of a welding unit
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

32. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
Guns
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%
Welding process that joins metals by heating them with an electric arc

33. What is the effect of too much slope?
Generally not as accurate
5.8 to 12.5 L/min
Insufficient current to melt the wire off cleanly
Pressure vessels and the piping industry

34. List 3 forms compressed gases may be supplied for welding
Puddle fluidity
Minutes of elapsed time continually run (out of 10 minutes)
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
National Electrical Manufactures Association

35. Why is a fiber washer required and what cylinder gas requires it?
Generally not as accurate
To prevent leakage - Carbon Dioxide (CO2)
When the filler wire is in direct contract with the base metal
Flux cored wires

36. What is the required arc voltage used for short circuit transfer?
Cause flaking - which can clog the liner and contact tube
Guns
Short- circuiting transfer - Globular transfer - Spray transfer
12 to 22 arc volts

37. List the three methods of metal transfer with GMAW
Short- circuiting transfer - Globular transfer - Spray transfer
By there current carrying capacity
12 to 22 arc volts
If you dont know this check your phone

38. Why is globular transfer generally avoided with GMAW?
3
Penetration and burn - off rate of the electrode
Spatter problems and poor weld appearance
Gas metal arc welding

39. Why must CO2 cylinders be used in the vertical position?
85%
To prevent drawing of liquid CO2 (Carbon Dioxide)
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

40. Regulators control_____________ flowmeters SHOW____________.
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
Pressure - The rate of flow of a shielding gas
To prevent drawing of liquid CO2 (Carbon Dioxide)
Gives arc voltage values to the control system of the feeder

41. What does the term GMAW identify?
Wire feed speed
Gas metal arc welding
(DCEP) Direct Current Electrode Positive or Reverse polarity
If you dont know this check your phone

42. How many times per second does short circuiting take place?
20 to 200 times per second
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Cause flaking - which can clog the liner and contact tube
Aluminum wire

43. What effect does increasing and decreasing the inductance have on the weld?
These terms are quite restrictive and often technically incorrect
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
To limit the short circuiting current so that spatter is reduced

44. Give a brief description of the GMAW process
By there current carrying capacity
Welding process that joins metals by heating them with an electric arc
Insufficient current to melt the wire off cleanly
Constant voltage (CV)

45. What happens when the electrode extension is increased?
Welding process that joins metals by heating them with an electric arc
The resistace to electrical current flow increases with it. Causing the electrode to heat
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Short- circuiting transfer - Globular transfer - Spray transfer

46. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
Minutes of elapsed time continually run (out of 10 minutes)
If you dont know this check your phone
Spatter problems and poor weld appearance
The time rate of response for the current rise and fall

47. What 2 organizations designate specifications for GMAW wires?
5.8 to 12.5 L/min
AWS and CSA
Guns
Cause flaking - which can clog the liner and contact tube

48. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
5.8 to 12.5 L/min
These terms are quite restrictive and often technically incorrect
Insufficient current to melt the wire off cleanly
Higher 26 to 35 arc volts

49. Why is the term GMAW preferred over MIG or MAG?
1/4 inch to 1/2 inch
These terms are quite restrictive and often technically incorrect
Reducing the gas source pressure to a constant working pressure
If you dont know this check your phone

50. Draw a typical volt amp curve for a machine that is designed for GMAW
Insufficient current to melt the wire off cleanly
Controls the rate of flow of a shielding gas to the gun nozzle
If you dont know this check your phone
Constant- speed wire feeders and Voltage- sennsing wire feeders