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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 is the purpose of the pick- up lead on a voltage sensing wire feeder?
DCEP (Direct Current Electrode Positive) Reverse Polarity
The time rate of response for the current rise and fall
Gives arc voltage values to the control system of the feeder
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2. What 2 organizations designate specifications for GMAW wires?
Puddle fluidity
AWS and CSA
Penetration and burn - off rate of the electrode
85%

3. Give a brief description of the GMAW process
Welding process that joins metals by heating them with an electric arc
Flux cored wires
Spatter problems and poor weld appearance
Insufficient current to melt the wire off cleanly

4. Why must CO2 cylinders be used in the vertical position?
Reducing the gas source pressure to a constant working pressure
The time rate of response for the current rise and fall
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

5. What is the effect of too much slope?
...
Insufficient current to melt the wire off cleanly
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Welding process that joins metals by heating them with an electric arc

6. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
Reducing the gas source pressure to a constant working pressure
3
Voltage is the force that overcomes resistance to allow amperage flow
Duty cycle

7. What output on the welding machine is used to rate the duty cycle?
85%
Minutes of elapsed time continually run (out of 10 minutes)
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
V groove or U groove

8. What is the key advantage of short circuiting transfer?
Minimum distortion due to low heat input
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
1/4 inch to 1/2 inch
Generally not as accurate

9. What is the recommended electrode stick- out for .035 solid wire?
1/4 inch to 1/2 inch
To prevent drawing of liquid CO2 (Carbon Dioxide)
Constant current (CC)
Minimum distortion due to low heat input

10. Regulators control_____________ flowmeters SHOW____________.
Gives arc voltage values to the control system of the feeder
Welding process that joins metals by heating them with an electric arc
1/4 inch to 1/2 inch
Pressure - The rate of flow of a shielding gas

11. What effect does increasing and decreasing the inductance have on the weld?
Minutes of elapsed time continually run (out of 10 minutes)
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Guns
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

12. Draw a typical volt amp curve for a machine that is designed for GMAW
Constant current (CC)
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Minutes of elapsed time continually run (out of 10 minutes)
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13. A pull type drive system is usually used on what type of material?
Higher 26 to 35 arc volts
Aluminum wire
Voltage is the force that overcomes resistance to allow amperage flow
The Arc voltage

14. What is the maximum distance that hard wire can be successfully pushed?
12 to 22 arc volts
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15 feet (4.5 meters)
Wire feed speed - Voltage control

15. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
(DCEP) Direct Current Electrode Positive or Reverse polarity
The resistace to electrical current flow increases with it. Causing the electrode to heat
Reducing the gas source pressure to a constant working pressure
The Arc voltage

16. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or 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
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SMAW - GTAW
Wire feed speed

17. What is another term for electrode holders for GMAW?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Guns
Constant current (CC)
These terms are quite restrictive and often technically incorrect

18. When is the metal transferred with short circuit transfer?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Pressure vessels and the piping industry
Insufficient current to melt the wire off cleanly
When the filler wire is in direct contract with the base metal

19. What 2 controls are found on a GMAW set- up?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Dry ice can form within the flow control openings and cause blockage of shielding gas
Wire feed speed - Voltage control
V groove or U groove

20. What processes are constant current (CC) power sources designed to be used with?
Dry ice can form within the flow control openings and cause blockage of shielding gas
Speed of the feed motor and - starting / stopping electrode feed
SMAW - GTAW
To prevent leakage - Carbon Dioxide (CO2)

21. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Cause flaking - which can clog the liner and contact tube
Aluminum wire
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

22. What is the preferred drive roll design for solid wires?
V groove or U groove
Puddle fluidity
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Duty cycle

23. What is the purpose of a regulator and what does it indicate on its gauges?
When the filler wire is in direct contract with the base metal
Gas metal arc welding
Reducing the gas source pressure to a constant working pressure
The resistace to electrical current flow increases with it. Causing the electrode to heat

24. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
...
Controls the rate of flow of a shielding gas to the gun nozzle
Insufficient current to melt the wire off cleanly
5.8 to 12.5 L/min

25. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Generally not as accurate
Penetration and burn - off rate of the electrode
Constant voltage (CV)
Dry ice can form within the flow control openings and cause blockage of shielding gas

26. In the GMAW process what does amperage control?
To prevent leakage - Carbon Dioxide (CO2)
Penetration and burn - off rate of the electrode
To prevent drawing of liquid CO2 (Carbon Dioxide)
Flux cored wires

27. How are GMAW guns rated?
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
By there current carrying capacity
Constant current (CC)

28. List 3 forms compressed gases may be supplied for welding
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
When the filler wire is in direct contract with the base metal
DCEP (Direct Current Electrode Positive) Reverse Polarity
15 feet (4.5 meters)

29. What would be an indication that the drive roll pressure is adjusted correctly?
Speed of the feed motor and - starting / stopping electrode feed
Gas metal arc welding
Controls the rate of flow of a shielding gas to the gun nozzle
Wire feeds smoothly (yet will slip should a problem occur in the gun)

30. What power sources are used with the GMAW Process?
1/4 inch to 1/2 inch
Dry ice can form within the flow control openings and cause blockage of shielding gas
Motor driven generators - Transformer rectifiers - and Inverter designs
15 feet (4.5 meters)

31. Why is a fiber washer required and what cylinder gas requires it?
Puddle fluidity
To prevent leakage - Carbon Dioxide (CO2)
Gives arc voltage values to the control system of the feeder
3

32. What is the main purpose of 'slope'?
If you dont know this check your phone
(DCEP) Direct Current Electrode Positive or Reverse polarity
To limit the short circuiting current so that spatter is reduced
Constant voltage (CV)

33. What controls the wire speed on a voltage sensing wire feeder?
Pressure - The rate of flow of a shielding gas
Guns
The Arc voltage
If you dont know this check your phone

34. What type of power source is commonly used with a voltage sensing wire feeder?
The Arc voltage
Constant current (CC)
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Generally not as accurate

35. Give a description of 'pinch effect'
Spatter problems and poor weld appearance
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Reducing the gas source pressure to a constant working pressure

36. What wire are knurled drive rolls most commonly used on?
Puddle fluidity
Spatter problems and poor weld appearance
Constant current (CC)
Flux cored wires

37. List the three methods of metal transfer with GMAW
Wire feed speed - Voltage control
85%
20 to 200 times per second
Short- circuiting transfer - Globular transfer - Spray transfer

38. What is an advantage of pulsed arc transfer with GMAW?
15 feet (4.5 meters)
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
12 to 22 arc volts
Spatter problems and poor weld appearance

39. In the GMAW process what does voltage control?
(DCEP) Direct Current Electrode Positive or Reverse polarity
85%
Gives arc voltage values to the control system of the feeder
Puddle fluidity

40. What does the term GMAW identify?
Shielding the molten weld metal from atmospheric contamination
5.8 to 12.5 L/min
Gas metal arc welding
Minutes of elapsed time continually run (out of 10 minutes)

41. List the factors that determine the mode of metal transfer
V groove or U groove
Cause flaking - which can clog the liner and contact tube
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
These terms are quite restrictive and often technically incorrect

42. List several industries that would use GMAW
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Pressure vessels and the piping industry
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
Insufficient current to melt the wire off cleanly

43. What does inductance control?
Duty cycle
Generally not as accurate
Pressure - The rate of flow of a shielding gas
The time rate of response for the current rise and fall

44. Why is globular transfer generally avoided with GMAW?
Spatter problems and poor weld appearance
Insufficient current to melt the wire off cleanly
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
12 to 22 arc volts

45. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Guns
Higher 26 to 35 arc volts
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Wire feed speed

46. What are the 2 types of wire feeders available?
Constant- speed wire feeders and Voltage- sennsing wire feeders
Puddle fluidity
Constant voltage (CV)
The negative side of a welding unit

47. What type of power source is used with a constant speed wire feeder?
Gives arc voltage values to the control system of the feeder
To prevent drawing of liquid CO2 (Carbon Dioxide)
Constant voltage (CV)
AWS and CSA

48. What does a flowmeter do and what does it measure?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Controls the rate of flow of a shielding gas to the gun nozzle
1/4 inch to 1/2 inch
Constant- speed wire feeders and Voltage- sennsing wire feeders

49. What does the wire feeder control?
Minutes of elapsed time continually run (out of 10 minutes)
Penetration and burn - off rate of the electrode
Spatter problems and poor weld appearance
Speed of the feed motor and - starting / stopping electrode feed

50. A 10 minute cycle of welding time vs cooling time a given machine can handle.
(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
Minimum distortion due to low heat input
Duty cycle