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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 an advantage of pulsed arc transfer with GMAW?
Dry ice can form within the flow control openings and cause blockage of shielding gas
National Electrical Manufactures Association
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
The Arc voltage

2. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
Controls the rate of flow of a shielding gas to the gun nozzle
Gives arc voltage values to the control system of the feeder
(DCEP) Direct Current Electrode Positive or Reverse polarity
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

3. A pull type drive system is usually used on what type of material?
Aluminum wire
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 resistace to electrical current flow increases with it. Causing the electrode to heat
Constant- speed wire feeders and Voltage- sennsing wire feeders

4. How many times per second does short circuiting take place?
20 to 200 times per second
Reducing the gas source pressure to a constant working pressure
These terms are quite restrictive and often technically incorrect
Insufficient current to melt the wire off cleanly

5. What wire are knurled drive rolls most commonly used on?
85%
Flux cored wires
Constant voltage (CV)
Minutes of elapsed time continually run (out of 10 minutes)

6. What is the purpose of the shielding gas used in GMAW?
Shielding the molten weld metal from atmospheric contamination
5.8 to 12.5 L/min
To limit the short circuiting current so that spatter is reduced
Dry ice can form within the flow control openings and cause blockage of shielding gas

7. Why is a fiber washer required and what cylinder gas requires it?
To prevent leakage - Carbon Dioxide (CO2)
DCEP (Direct Current Electrode Positive) Reverse Polarity
V groove or U groove
Reducing the gas source pressure to a constant working pressure

8. What power sources are used with the GMAW Process?
Motor driven generators - Transformer rectifiers - and Inverter designs
Welding process that joins metals by heating them with an electric arc
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Penetration and burn - off rate of the electrode

9. 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
15 feet (4.5 meters)
When the filler wire is in direct contract with the base metal
3

10. What type of power source is used with a constant speed wire feeder?
V groove or U groove
Generally not as accurate
Constant voltage (CV)
Controls the rate of flow of a shielding gas to the gun nozzle

11. What is the purpose of a regulator and what does it indicate on its gauges?
Short- circuiting transfer - Globular transfer - Spray transfer
Reducing the gas source pressure to a constant working pressure
Controls the rate of flow of a shielding gas to the gun nozzle
Wire feed speed

12. A 10 minute cycle of welding time vs cooling time a given machine can handle.
When the filler wire is in direct contract with the base metal
5.8 to 12.5 L/min
20 to 200 times per second
Duty cycle

13. What does the abbreviation NEMA stand for?
The resistace to electrical current flow increases with it. Causing the electrode to heat
15 feet (4.5 meters)
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
National Electrical Manufactures Association

14. What is the required arc voltage used for short circuit transfer?
12 to 22 arc volts
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Pressure - The rate of flow of a shielding gas
AWS and CSA

15. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Voltage is the force that overcomes resistance to allow amperage flow
Cause flaking - which can clog the liner and contact tube
When the filler wire is in direct contract with the base metal
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

16. 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
Shielding the molten weld metal from atmospheric contamination
Duty cycle
AWS and CSA

17. Why must CO2 cylinders be used in the vertical position?
If you dont know this check your phone
Shielding the molten weld metal from atmospheric contamination
Gives arc voltage values to the control system of the feeder
To prevent drawing of liquid CO2 (Carbon Dioxide)

18. What is the effect of too much slope?
Insufficient current to melt the wire off cleanly
Cause flaking - which can clog the liner and contact tube
The resistace to electrical current flow increases with it. Causing the electrode to heat
V groove or U groove

19. Regulators control_____________ flowmeters SHOW____________.
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Pressure - The rate of flow of a shielding gas
Constant voltage (CV)

20. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
Constant current (CC)
Reducing the gas source pressure to a constant working pressure
85%
Gives arc voltage values to the control system of the feeder

21. What output on the welding machine is used to rate the duty cycle?
Minutes of elapsed time continually run (out of 10 minutes)
(DCEP) Direct Current Electrode Positive or Reverse polarity
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

22. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
V groove or U groove
Wire feed speed - Voltage control
...
Speed of the feed motor and - starting / stopping electrode feed

23. Why is globular transfer generally avoided with GMAW?
Constant- speed wire feeders and Voltage- sennsing wire feeders
DCEP (Direct Current Electrode Positive) Reverse Polarity
Welding process that joins metals by heating them with an electric arc
Spatter problems and poor weld appearance

24. What current and polarity is generally used with GMAW?
Short- circuiting transfer - Globular transfer - Spray transfer
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
DCEP (Direct Current Electrode Positive) Reverse Polarity
National Electrical Manufactures Association

25. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Dry ice can form within the flow control openings and cause blockage of shielding gas
...
3

26. What does the wire feeder control?
Constant voltage (CV)
Pressure - The rate of flow of a shielding gas
Wire feed speed - Voltage control
Speed of the feed motor and - starting / stopping electrode feed

27. Why is a line heater required when using GMAW?
Dry ice can form within the flow control openings and cause blockage of shielding gas
85%
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
15 feet (4.5 meters)

28. Give a description of 'pinch effect'
Minimum distortion due to low heat input
These terms are quite restrictive and often technically incorrect
The negative side of a welding unit
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

29. Why is the term GMAW preferred over MIG or MAG?
Short- circuiting transfer - Globular transfer - Spray transfer
The resistace to electrical current flow increases with it. Causing the electrode to heat
Motor driven generators - Transformer rectifiers - and Inverter designs
These terms are quite restrictive and often technically incorrect

30. List the basic equipment requirements for the GMAW process
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
To prevent drawing of liquid CO2 (Carbon Dioxide)
...

31. What would be an indication that the drive roll pressure is adjusted correctly?
Insufficient current to melt the wire off cleanly
Constant- speed wire feeders and Voltage- sennsing wire feeders
Wire feeds smoothly (yet will slip should a problem occur in the gun)
SMAW - GTAW

32. What is the key advantage of short circuiting transfer?
Spatter problems and poor weld appearance
Insufficient current to melt the wire off cleanly
Minimum distortion due to low heat input
Wire feed speed

33. 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
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
V groove or U groove

34. In the GMAW process what does amperage control?
Minutes of elapsed time continually run (out of 10 minutes)
Penetration and burn - off rate of the electrode
Insufficient current to melt the wire off cleanly
3

35. What does the term GMAW identify?
V groove or U groove
Generally not as accurate
1/4 inch to 1/2 inch
Gas metal arc welding

36. What processes are constant current (CC) power sources designed to be used with?
AWS and CSA
Constant current (CC)
SMAW - GTAW
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

37. What controls amperage when using GMAW?
By there current carrying capacity
V groove or U groove
1/4 inch to 1/2 inch
Wire feed speed

38. What is the main purpose of 'slope'?
To limit the short circuiting current so that spatter is reduced
Penetration and burn - off rate of the electrode
Constant voltage (CV)
Motor driven generators - Transformer rectifiers - and Inverter designs

39. With straight polarity where is 2/3 of the arc energy?
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
The negative side of a welding unit
Insufficient current to melt the wire off cleanly

40. What is another term for electrode holders for GMAW?
Generally not as accurate
Guns
Duty cycle
Constant current (CC)

41. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Minimum distortion due to low heat input
The Arc voltage
1/4 inch to 1/2 inch
Higher 26 to 35 arc volts

42. What does voltage do in an electrical circuit?
The resistace to electrical current flow increases with it. Causing the electrode to heat
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
Wire feed speed - Voltage control

43. What controls the wire speed on a voltage sensing wire feeder?
The Arc voltage
Motor driven generators - Transformer rectifiers - and Inverter designs
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
To prevent drawing of liquid CO2 (Carbon Dioxide)

44. What type of power source is commonly used with a voltage sensing wire feeder?
Constant current (CC)
Puddle fluidity
Shielding the molten weld metal from atmospheric contamination
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

45. What is a typical flow rate of CO2 for short circuit transfer?
15 feet (4.5 meters)
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 prevent leakage - Carbon Dioxide (CO2)
5.8 to 12.5 L/min

46. List the factors that determine the mode of metal transfer
To prevent leakage - Carbon Dioxide (CO2)
The Arc voltage
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)

47. What 2 controls are found on a GMAW set- up?
AWS and CSA
Wire feed speed - Voltage control
Shielding the molten weld metal from atmospheric contamination
12 to 22 arc volts

48. 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
If you dont know this check your phone
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

49. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
Penetration and burn - off rate of the electrode
If you dont know this check your phone
To limit the short circuiting current so that spatter is reduced
Constant current (CC)

50. What does a flowmeter do and what does it measure?
The resistace to electrical current flow increases with it. Causing the electrode to heat
The time rate of response for the current rise and fall
Short- circuiting transfer - Globular transfer - Spray transfer
Controls the rate of flow of a shielding gas to the gun nozzle