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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 recommended electrode stick- out for .035 solid wire?
The resistace to electrical current flow increases with it. Causing the electrode to heat
Guns
1/4 inch to 1/2 inch
85%

2. List the three methods of metal transfer with GMAW
The resistace to electrical current flow increases with it. Causing the electrode to heat
Short- circuiting transfer - Globular transfer - Spray transfer
When the filler wire is in direct contract with the base metal
Duty cycle

3. What current and polarity is generally used with GMAW?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Minutes of elapsed time continually run (out of 10 minutes)
Constant- speed wire feeders and Voltage- sennsing wire feeders
Flux cored wires

4. List the basic equipment requirements for the GMAW process
15 feet (4.5 meters)
Spatter problems and poor weld appearance
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
DCEP (Direct Current Electrode Positive) Reverse Polarity

5. What output on the welding machine is used to rate the duty cycle?
Minutes of elapsed time continually run (out of 10 minutes)
Dry ice can form within the flow control openings and cause blockage of shielding gas
Insufficient current to melt the wire off cleanly
Gives arc voltage values to the control system of the feeder

6. Why is the term GMAW preferred over MIG or MAG?
(DCEP) Direct Current Electrode Positive or Reverse polarity
Guns
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
These terms are quite restrictive and often technically incorrect

7. What does a flowmeter do and what does it measure?
Generally not as accurate
The Arc voltage
Controls the rate of flow of a shielding gas to the gun nozzle
Gives arc voltage values to the control system of the feeder

8. What processes are constant current (CC) power sources designed to be used with?
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
SMAW - GTAW
Higher 26 to 35 arc volts
12 to 22 arc volts

9. In the GMAW process what does amperage control?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Motor driven generators - Transformer rectifiers - and Inverter designs
To prevent leakage - Carbon Dioxide (CO2)
Penetration and burn - off rate of the electrode

10. List 3 wire drive systems and give a short description of each
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
Flux cored wires
Short- circuiting transfer - Globular transfer - Spray transfer

11. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
3
Dry ice can form within the flow control openings and cause blockage of shielding gas
To prevent leakage - Carbon Dioxide (CO2)
Wire feeds smoothly (yet will slip should a problem occur in the gun)

12. What effect does increasing and decreasing the inductance have on the weld?
Puddle fluidity
Cause flaking - which can clog the liner and contact tube
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
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

13. What is an advantage of pulsed arc transfer with GMAW?
Voltage is the force that overcomes resistance to allow amperage flow
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
85%
Minutes of elapsed time continually run (out of 10 minutes)

14. What is the key advantage of short circuiting transfer?
Minimum distortion due to low heat input
Wire feeds smoothly (yet will slip should a problem occur in the gun)
The resistace to electrical current flow increases with it. Causing the electrode to heat
When the filler wire is in direct contract with the base metal

15. How many times per second does short circuiting take place?
15 feet (4.5 meters)
National Electrical Manufactures Association
DCEP (Direct Current Electrode Positive) Reverse Polarity
20 to 200 times per second

16. What happens when the electrode extension is increased?
The resistace to electrical current flow increases with it. Causing the electrode to heat
Gives arc voltage values to the control system of the feeder
Pressure vessels and the piping industry
Higher 26 to 35 arc volts

17. Give a description of 'pinch effect'
To prevent leakage - Carbon Dioxide (CO2)
DCEP (Direct Current Electrode Positive) Reverse Polarity
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
The Arc voltage

18. What 2 organizations designate specifications for GMAW wires?
Pressure vessels and the piping industry
AWS and CSA
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Motor driven generators - Transformer rectifiers - and Inverter designs

19. What type of power source is commonly used with a voltage sensing wire feeder?
AWS and CSA
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
Pressure vessels and the piping industry

20. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
Reducing the gas source pressure to a constant working pressure
Dry ice can form within the flow control openings and cause blockage of shielding gas
AWS and CSA
...

21. Why must CO2 cylinders be used in the vertical position?
AWS and CSA
Shielding the molten weld metal from atmospheric contamination
Duty cycle
To prevent drawing of liquid CO2 (Carbon Dioxide)

22. List 3 forms compressed gases may be supplied for welding
85%
To prevent drawing of liquid CO2 (Carbon Dioxide)
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Shielding the molten weld metal from atmospheric contamination

23. A 10 minute cycle of welding time vs cooling time a given machine can handle.
The resistace to electrical current flow increases with it. Causing the electrode to heat
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Generally not as accurate
Duty cycle

24. What is the maximum distance that hard wire can be successfully pushed?
Dry ice can form within the flow control openings and cause blockage of shielding gas
Short- circuiting transfer - Globular transfer - Spray transfer
15 feet (4.5 meters)
Constant voltage (CV)

25. What does voltage do in an electrical circuit?
SMAW - GTAW
Minutes of elapsed time continually run (out of 10 minutes)
Speed of the feed motor and - starting / stopping electrode feed
Voltage is the force that overcomes resistance to allow amperage flow

26. How are GMAW guns rated?
By there current carrying capacity
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Gas metal arc welding
Motor driven generators - Transformer rectifiers - and Inverter designs

27. 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
By there current carrying capacity
Puddle fluidity
Insufficient current to melt the wire off cleanly

28. What does the abbreviation NEMA stand for?
Dry ice can form within the flow control openings and cause blockage of shielding gas
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
Wire feed speed
National Electrical Manufactures Association

29. Why is globular transfer generally avoided with GMAW?
To prevent leakage - Carbon Dioxide (CO2)
Spatter problems and poor weld appearance
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

30. Draw a typical volt amp curve for a machine that is designed for GMAW
If you dont know this check your phone
The time rate of response for the current rise and fall
The Arc voltage
Gives arc voltage values to the control system of the feeder

31. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
Wire feed speed - Voltage control
85%
AWS and CSA
By there current carrying capacity

32. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
3
Controls the rate of flow of a shielding gas to the gun nozzle
(DCEP) Direct Current Electrode Positive or Reverse polarity
Minutes of elapsed time continually run (out of 10 minutes)

33. What does the wire feeder control?
National Electrical Manufactures Association
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Speed of the feed motor and - starting / stopping electrode feed

34. What is the effect of too much slope?
Puddle fluidity
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
Insufficient current to melt the wire off cleanly

35. What is a typical flow rate of CO2 for short circuit transfer?
Short- circuiting transfer - Globular transfer - Spray transfer
5.8 to 12.5 L/min
Pressure vessels and the piping industry
The resistace to electrical current flow increases with it. Causing the electrode to heat

36. What is the main purpose of 'slope'?
Wire feed speed
DCEP (Direct Current Electrode Positive) Reverse Polarity
To limit the short circuiting current so that spatter is reduced
1/4 inch to 1/2 inch

37. What wire are knurled drive rolls most commonly used on?
Flux cored wires
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
20 to 200 times per second
Shielding the molten weld metal from atmospheric contamination

38. What is the required arc voltage used for short circuit transfer?
Constant- speed wire feeders and Voltage- sennsing wire feeders
If you dont know this check your phone
12 to 22 arc volts
20 to 200 times per second

39. What is another term for electrode holders for GMAW?
Guns
...
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Pressure - The rate of flow of a shielding gas

40. What controls amperage when using GMAW?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Wire feed speed
5.8 to 12.5 L/min
Controls the rate of flow of a shielding gas to the gun nozzle

41. What is the purpose of a regulator and what does it indicate on its gauges?
...
Reducing the gas source pressure to a constant working pressure
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
The time rate of response for the current rise and fall

42. What is the purpose of the shielding gas used in GMAW?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Shielding the molten weld metal from atmospheric contamination
Gives arc voltage values to the control system of the feeder
(DCEP) Direct Current Electrode Positive or Reverse polarity

43. Give a brief description of the GMAW process
Welding process that joins metals by heating them with an electric arc
Shielding the molten weld metal from atmospheric contamination
3
The Arc voltage

44. Why is a fiber washer required and what cylinder gas requires it?
Pressure - The rate of flow of a shielding gas
(DCEP) Direct Current Electrode Positive or Reverse polarity
Constant current (CC)
To prevent leakage - Carbon Dioxide (CO2)

45. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Pressure vessels and the piping industry
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
Dry ice can form within the flow control openings and cause blockage of shielding gas

46. With straight polarity where is 2/3 of the arc energy?
Flux cored wires
20 to 200 times per second
The negative side of a welding unit
85%

47. What is the disadvantage of the gauge preset type of regulator/flowmeter?
The resistace to electrical current flow increases with it. Causing the electrode to heat
Generally not as accurate
AWS and CSA
When the filler wire is in direct contract with the base metal

48. What does the term GMAW identify?
When the filler wire is in direct contract with the base metal
The Arc voltage
Gas metal arc welding
Pressure - The rate of flow of a shielding gas

49. What would be an indication that the drive roll pressure is adjusted correctly?
Controls the rate of flow of a shielding gas to the gun nozzle
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Wire feeds smoothly (yet will slip should a problem occur in the gun)
To limit the short circuiting current so that spatter is reduced

50. What type of power source is used with a constant speed wire feeder?
When the filler wire is in direct contract with the base metal
To limit the short circuiting current so that spatter is reduced
Motor driven generators - Transformer rectifiers - and Inverter designs
Constant voltage (CV)