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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 does a flowmeter do and what does it measure?
Dry ice can form within the flow control openings and cause blockage of shielding gas
Controls the rate of flow of a shielding gas to the gun nozzle
To limit the short circuiting current so that spatter is reduced
Constant voltage (CV)

2. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Higher 26 to 35 arc volts
To prevent drawing of liquid CO2 (Carbon Dioxide)
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 or Reverse polarity

3. List 3 wire drive systems and give a short description of each
Reducing the gas source pressure to a constant working pressure
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 - Voltage control
Welding process that joins metals by heating them with an electric arc

4. How are GMAW guns rated?
(DCEP) Direct Current Electrode Positive or Reverse polarity
1/4 inch to 1/2 inch
Controls the rate of flow of a shielding gas to the gun nozzle
By there current carrying capacity

5. How many times per second does short circuiting take place?
20 to 200 times per second
Penetration and burn - off rate of the electrode
Guns
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

6. 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
Insufficient current to melt the wire off cleanly
(DCEP) Direct Current Electrode Positive or Reverse polarity
Shielding the molten weld metal from atmospheric contamination

7. What 2 controls are found on a GMAW set- up?
If you dont know this check your phone
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
3
Wire feed speed - Voltage control

8. What power sources are used with the GMAW Process?
Motor driven generators - Transformer rectifiers - and Inverter designs
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
AWS and CSA

9. What happens when the electrode extension is increased?
Duty cycle
Higher 26 to 35 arc volts
1/4 inch to 1/2 inch
The resistace to electrical current flow increases with it. Causing the electrode to heat

10. What is a typical flow rate of CO2 for short circuit transfer?
The negative side of a welding unit
The time rate of response for the current rise and fall
Duty cycle
5.8 to 12.5 L/min

11. What does inductance control?
Aluminum wire
Minimum distortion due to low heat input
The time rate of response for the current rise and fall
Reducing the gas source pressure to a constant working pressure

12. What is the purpose of the shielding gas used in GMAW?
Minimum distortion due to low heat input
Shielding the molten weld metal from atmospheric contamination
Reducing the gas source pressure to a constant working pressure
20 to 200 times per second

13. What are the 2 types of wire feeders available?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Constant- speed wire feeders and Voltage- sennsing wire feeders
15 feet (4.5 meters)
To limit the short circuiting current so that spatter is reduced

14. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
Pressure - The rate of flow of a shielding gas
Wire feed speed
85%
...

15. What is the effect of too much slope?
Duty cycle
Insufficient current to melt the wire off cleanly
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
AWS and CSA

16. List the basic equipment requirements for the GMAW process
Minimum distortion due to low heat input
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
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

17. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Constant voltage (CV)
15 feet (4.5 meters)
If you dont know this check your phone
Duty cycle

18. Why is a fiber washer required and what cylinder gas requires it?
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
Spatter problems and poor weld appearance
Aluminum wire
To prevent leakage - Carbon Dioxide (CO2)

19. What processes are constant current (CC) power sources designed to be used with?
Speed of the feed motor and - starting / stopping electrode feed
SMAW - GTAW
15 feet (4.5 meters)
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

20. What type of power source is used with a constant speed wire feeder?
Constant voltage (CV)
The resistace to electrical current flow increases with it. Causing the electrode to heat
Reducing the gas source pressure to a constant working pressure
Minutes of elapsed time continually run (out of 10 minutes)

21. What is another term for electrode holders for GMAW?
Guns
AWS and CSA
Wire feed speed - Voltage control
15 feet (4.5 meters)

22. What is the preferred drive roll design for solid wires?
Duty cycle
20 to 200 times per second
Controls the rate of flow of a shielding gas to the gun nozzle
V groove or U groove

23. 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
Constant voltage (CV)
Flux cored wires
Penetration and burn - off rate of the electrode

24. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Pressure - The rate of flow of a shielding gas
Wire feed speed
...

25. Give a brief description of the GMAW process
To limit the short circuiting current so that spatter is reduced
The resistace to electrical current flow increases with it. Causing the electrode to heat
1/4 inch to 1/2 inch
Welding process that joins metals by heating them with an electric arc

26. What is the maximum distance that hard wire can be successfully pushed?
15 feet (4.5 meters)
AWS and CSA
Welding process that joins metals by heating them with an electric arc
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

27. With straight polarity where is 2/3 of the arc energy?
To prevent leakage - Carbon Dioxide (CO2)
The negative side of a welding unit
Constant current (CC)
The resistace to electrical current flow increases with it. Causing the electrode to heat

28. What is the required arc voltage used for short circuit transfer?
Controls the rate of flow of a shielding gas to the gun nozzle
If you dont know this check your phone
12 to 22 arc volts
If you dont know this check your phone

29. List the factors that determine the mode of metal transfer
Gas metal arc welding
SMAW - GTAW
Constant voltage (CV)
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

30. What is the recommended electrode stick- out for .035 solid wire?
Penetration and burn - off rate of the electrode
Spatter problems and poor weld appearance
Speed of the feed motor and - starting / stopping electrode feed
1/4 inch to 1/2 inch

31. When is the metal transferred with short circuit transfer?
The time rate of response for the current rise and fall
To prevent leakage - Carbon Dioxide (CO2)
20 to 200 times per second
When the filler wire is in direct contract with the base metal

32. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
When the filler wire is in direct contract with the base metal
Pressure - The rate of flow of a shielding gas
DCEP (Direct Current Electrode Positive) Reverse Polarity
Gives arc voltage values to the control system of the feeder

33. What controls the wire speed on a voltage sensing wire feeder?
Wire feed speed
The Arc voltage
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

34. What does the term GMAW identify?
The resistace to electrical current flow increases with it. Causing the electrode to heat
Higher 26 to 35 arc volts
Gas metal arc welding
Short- circuiting transfer - Globular transfer - Spray transfer

35. Draw a typical volt amp curve for a machine that is designed for GMAW
Insufficient current to melt the wire off cleanly
If you dont know this check your phone
Spatter problems and poor weld appearance
Constant voltage (CV)

36. Give a description of 'pinch effect'
Puddle fluidity
Penetration and burn - off rate of the electrode
Pressure - The rate of flow of a shielding gas
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

37. What does voltage do in an electrical circuit?
Voltage is the force that overcomes resistance to allow amperage flow
Wire feeds smoothly (yet will slip should a problem occur in the gun)
These terms are quite restrictive and often technically incorrect
Motor driven generators - Transformer rectifiers - and Inverter designs

38. List several industries that would use GMAW
Minimum distortion due to low heat input
Gas metal arc welding
Pressure vessels and the piping industry
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

39. Why is globular transfer generally avoided with GMAW?
Short- circuiting transfer - Globular transfer - Spray transfer
Penetration and burn - off rate of the electrode
Spatter problems and poor weld appearance
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

40. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Generally not as accurate
12 to 22 arc volts
Cause flaking - which can clog the liner and contact tube

41. 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)
Shielding the molten weld metal from atmospheric contamination
V groove or U groove

42. What type of power source is commonly used with a voltage sensing wire feeder?
Constant current (CC)
12 to 22 arc volts
Motor driven generators - Transformer rectifiers - and Inverter designs
Speed of the feed motor and - starting / stopping electrode feed

43. Why must CO2 cylinders be used in the vertical position?
To prevent drawing of liquid CO2 (Carbon Dioxide)
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
National Electrical Manufactures Association

44. What does the abbreviation NEMA stand for?
By there current carrying capacity
National Electrical Manufactures Association
To limit the short circuiting current so that spatter is reduced
Wire feeds smoothly (yet will slip should a problem occur in the gun)

45. In the GMAW process what does voltage control?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Puddle fluidity
Dry ice can form within the flow control openings and cause blockage of shielding gas
Aluminum wire

46. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Flux cored wires
Aluminum wire
To limit the short circuiting current so that spatter is reduced
Cause flaking - which can clog the liner and contact tube

47. Why is a line heater required when using GMAW?
Dry ice can form within the flow control openings and cause blockage of shielding gas
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
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 negative side of a welding unit

48. What wire are knurled drive rolls most commonly used on?
Flux cored wires
12 to 22 arc volts
When the filler wire is in direct contract with the base metal
To limit the short circuiting current so that spatter is reduced

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

50. What is an advantage of pulsed arc transfer with GMAW?
15 feet (4.5 meters)
Motor driven generators - Transformer rectifiers - and Inverter designs
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