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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 wire are knurled drive rolls most commonly used on?
Flux cored wires
DCEP (Direct Current Electrode Positive) Reverse Polarity
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
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

2. Why is a fiber washer required and what cylinder gas requires it?
Controls the rate of flow of a shielding gas to the gun nozzle
National Electrical Manufactures Association
To prevent leakage - Carbon Dioxide (CO2)
Guns

3. 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)
Pressure vessels and the piping industry
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

4. What 2 organizations designate specifications for GMAW wires?
AWS and CSA
Higher 26 to 35 arc volts
Shielding the molten weld metal from atmospheric contamination
Speed of the feed motor and - starting / stopping electrode feed

5. Why must CO2 cylinders be used in the vertical position?
To prevent drawing of liquid CO2 (Carbon Dioxide)
3
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
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

6. List several industries that would use GMAW
Puddle fluidity
To limit the short circuiting current so that spatter is reduced
The time rate of response for the current rise and fall
Pressure vessels and the piping industry

7. What is the maximum distance that hard wire can be successfully pushed?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Constant- speed wire feeders and Voltage- sennsing wire feeders
15 feet (4.5 meters)
To prevent leakage - Carbon Dioxide (CO2)

8. What type of power source is used with a constant speed wire feeder?
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
Welding process that joins metals by heating them with an electric arc
Constant voltage (CV)

9. In the GMAW process what does voltage control?
Guns
Puddle fluidity
(DCEP) Direct Current Electrode Positive or Reverse polarity
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

10. 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
Dry ice can form within the flow control openings and cause blockage of shielding gas
The resistace to electrical current flow increases with it. Causing the electrode to heat

11. What is the main purpose of 'slope'?
1/4 inch to 1/2 inch
These terms are quite restrictive and often technically incorrect
To limit the short circuiting current so that spatter is reduced
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

12. 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
Insufficient current to melt the wire off cleanly
20 to 200 times per second
Wire feed speed

13. List the factors that determine the mode of metal transfer
Gas metal arc welding
...
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Minimum distortion due to low heat input

14. 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
Gives arc voltage values to the control system of the feeder
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
Constant current (CC)

15. Why is globular transfer generally avoided with GMAW?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
(DCEP) Direct Current Electrode Positive or Reverse polarity
Spatter problems and poor weld appearance
Voltage is the force that overcomes resistance to allow amperage flow

16. 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
The time rate of response for the current rise and fall
1/4 inch to 1/2 inch
AWS and CSA

17. What type of power source is commonly used with a voltage sensing wire feeder?
Duty cycle
Constant current (CC)
Guns
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

18. What is another term for electrode holders for GMAW?
Wire feed speed - Voltage control
...
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Guns

19. Why is a line heater required when using GMAW?
Wire feed speed - Voltage control
(DCEP) Direct Current Electrode Positive or Reverse polarity
Dry ice can form within the flow control openings and cause blockage of shielding gas
Motor driven generators - Transformer rectifiers - and Inverter designs

20. List 3 forms compressed gases may be supplied for welding
Wire feed speed - Voltage control
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Shielding the molten weld metal from atmospheric contamination
Aluminum wire

21. What does voltage do in an electrical circuit?
Guns
Cause flaking - which can clog the liner and contact tube
Voltage is the force that overcomes resistance to allow amperage flow
Duty cycle

22. What processes are constant current (CC) power sources designed to be used with?
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)
SMAW - GTAW
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

23. What does inductance control?
Voltage is the force that overcomes resistance to allow amperage flow
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
12 to 22 arc volts
The time rate of response for the current rise and fall

24. Why is the term GMAW preferred over MIG or MAG?
Constant current (CC)
Generally not as accurate
These terms are quite restrictive and often technically incorrect
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

25. Draw a typical volt amp curve for a machine that is designed for GMAW
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Spatter problems and poor weld appearance
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
If you dont know this check your phone

26. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Constant voltage (CV)
Gives arc voltage values to the control system of the feeder
(DCEP) Direct Current Electrode Positive or Reverse polarity
If you dont know this check your phone

27. What does a flowmeter do and what does it measure?
Reducing the gas source pressure to a constant working pressure
Shielding the molten weld metal from atmospheric contamination
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Controls the rate of flow of a shielding gas to the gun nozzle

28. What is the effect of too much slope?
Minimum distortion due to low heat input
If you dont know this check your phone
Insufficient current to melt the wire off cleanly
Wire feed speed

29. List 3 wire drive systems and give a short description of each
To prevent leakage - Carbon Dioxide (CO2)
(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

30. What is the preferred drive roll design for solid wires?
Welding process that joins metals by heating them with an electric arc
20 to 200 times per second
If you dont know this check your phone
V groove or U groove

31. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
These terms are quite restrictive and often technically incorrect
Voltage is the force that overcomes resistance to allow amperage flow
3
Constant current (CC)

32. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Higher 26 to 35 arc volts
Penetration and burn - off rate of the electrode
Welding process that joins metals by heating them with an electric arc
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

33. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Generally not as accurate
When the filler wire is in direct contract with the base metal
SMAW - GTAW
Pressure vessels and the piping industry

34. A 10 minute cycle of welding time vs cooling time a given machine can handle.
The negative side of a welding unit
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Constant- speed wire feeders and Voltage- sennsing wire feeders
Duty cycle

35. What power sources are used with the GMAW Process?
Motor driven generators - Transformer rectifiers - and Inverter designs
V groove or U groove
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Spatter problems and poor weld appearance

36. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
Spatter problems and poor weld appearance
...
5.8 to 12.5 L/min
Penetration and burn - off rate of the electrode

37. A pull type drive system is usually used on what type of material?
Motor driven generators - Transformer rectifiers - and Inverter designs
To prevent leakage - Carbon Dioxide (CO2)
Aluminum wire
Puddle fluidity

38. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
National Electrical Manufactures Association
Pressure vessels and the piping industry
85%
Shielding the molten weld metal from atmospheric contamination

39. List the three methods of metal transfer with GMAW
Pressure - The rate of flow of a shielding gas
Puddle fluidity
Short- circuiting transfer - Globular transfer - Spray transfer
3

40. What is the recommended electrode stick- out for .035 solid wire?
Pressure - The rate of flow of a shielding gas
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
1/4 inch to 1/2 inch
Duty cycle

41. 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
The time rate of response for the current rise and fall
...
Pressure - The rate of flow of a shielding gas

42. What is the required arc voltage used for short circuit transfer?
Pressure vessels and the piping industry
12 to 22 arc volts
Voltage is the force that overcomes resistance to allow amperage flow
Wire feed speed

43. What is the key advantage of short circuiting transfer?
Pressure vessels and the piping industry
Flux cored wires
Aluminum wire
Minimum distortion due to low heat input

44. What does the term GMAW identify?
National Electrical Manufactures Association
Gas metal arc welding
Minutes of elapsed time continually run (out of 10 minutes)
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

45. What controls amperage when using GMAW?
Wire feed speed
The resistace to electrical current flow increases with it. Causing the electrode to heat
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
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. Give a brief description of the GMAW process
Minutes of elapsed time continually run (out of 10 minutes)
Welding process that joins metals by heating them with an electric arc
Pressure - The rate of flow of a shielding gas
Motor driven generators - Transformer rectifiers - and Inverter designs

47. What is an advantage of pulsed arc transfer with GMAW?
Insufficient current to melt the wire off cleanly
Aluminum wire
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Spatter problems and poor weld appearance

48. Give a description of 'pinch effect'
Reducing the gas source pressure to a constant working pressure
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Guns

49. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
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
Dry ice can form within the flow control openings and cause blockage of shielding gas
Cause flaking - which can clog the liner and contact tube

50. With straight polarity where is 2/3 of the arc energy?
Penetration and burn - off rate of the electrode
The negative side of a welding unit
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field