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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. Give a description of 'pinch effect'
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Insufficient current to melt the wire off cleanly
Wire feed speed

2. What wire are knurled drive rolls most commonly used on?
If you dont know this check your phone
Flux cored wires
Controls the rate of flow of a shielding gas to the gun nozzle
The resistace to electrical current flow increases with it. Causing the electrode to heat

3. What is the disadvantage of the gauge preset type of regulator/flowmeter?
If you dont know this check your phone
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Generally not as accurate
Voltage is the force that overcomes resistance to allow amperage flow

4. What effect does increasing and decreasing the inductance have on the weld?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
85%
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

5. In the GMAW process what does amperage control?
Voltage is the force that overcomes resistance to allow amperage flow
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Penetration and burn - off rate of the electrode
(DCEP) Direct Current Electrode Positive or Reverse polarity

6. What type of power source is commonly used with a voltage sensing wire feeder?
To prevent drawing of liquid CO2 (Carbon Dioxide)
12 to 22 arc volts
Constant current (CC)
15 feet (4.5 meters)

7. What are the 2 types of wire feeders available?
The resistace to electrical current flow increases with it. Causing the electrode to heat
Wire feeds smoothly (yet will slip should a problem occur in the gun)
SMAW - GTAW
Constant- speed wire feeders and Voltage- sennsing wire feeders

8. What does voltage do in an electrical circuit?
Short- circuiting transfer - Globular transfer - Spray transfer
SMAW - GTAW
Duty cycle
Voltage is the force that overcomes resistance to allow amperage flow

9. Draw a typical volt amp curve for a machine that is designed for GMAW
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Wire feed speed
Gives arc voltage values to the control system of the feeder
If you dont know this check your phone

10. What does the abbreviation NEMA stand for?
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
Controls the rate of flow of a shielding gas to the gun nozzle
Higher 26 to 35 arc volts

11. What is a typical flow rate of CO2 for short circuit transfer?
Flux cored wires
5.8 to 12.5 L/min
Puddle fluidity
National Electrical Manufactures Association

12. List the factors that determine the mode of metal transfer
Wire feed speed - Voltage control
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
3
These terms are quite restrictive and often technically incorrect

13. Why is a line heater required when using GMAW?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Dry ice can form within the flow control openings and cause blockage of shielding gas
5.8 to 12.5 L/min
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

14. A pull type drive system is usually used on what type of material?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Guns
Welding process that joins metals by heating them with an electric arc
Aluminum wire

15. What is the main purpose of 'slope'?
Wire feed speed
Welding process that joins metals by heating them with an electric arc
The negative side of a welding unit
To limit the short circuiting current so that spatter is reduced

16. What is the purpose of a regulator and what does it indicate on its gauges?
Guns
5.8 to 12.5 L/min
Reducing the gas source pressure to a constant working pressure
Pressure - The rate of flow of a shielding gas

17. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Higher 26 to 35 arc volts
Motor driven generators - Transformer rectifiers - and Inverter designs
Cause flaking - which can clog the liner and contact tube
The resistace to electrical current flow increases with it. Causing the electrode to heat

18. What happens when the electrode extension is increased?
Generally not as accurate
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
The resistace to electrical current flow increases with it. Causing the electrode to heat

19. What power sources are used with the GMAW Process?
Motor driven generators - Transformer rectifiers - and Inverter designs
Dry ice can form within the flow control openings and cause blockage of shielding gas
Flux cored wires
Constant current (CC)

20. What is the preferred drive roll design for solid wires?
To prevent drawing of liquid CO2 (Carbon Dioxide)
V groove or U groove
Shielding the molten weld metal from atmospheric contamination
Penetration and burn - off rate of the electrode

21. Why is a fiber washer required and what cylinder gas requires it?
Wire feed speed - Voltage control
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Minutes of elapsed time continually run (out of 10 minutes)
To prevent leakage - Carbon Dioxide (CO2)

22. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
(DCEP) Direct Current Electrode Positive or Reverse polarity
Gives arc voltage values to the control system of the feeder
The resistace to electrical current flow increases with it. Causing the electrode to heat
SMAW - GTAW

23. In the GMAW process what does voltage control?
Puddle fluidity
V groove or U groove
The time rate of response for the current rise and fall
These terms are quite restrictive and often technically incorrect

24. What does inductance control?
Generally not as accurate
V groove or U groove
To prevent drawing of liquid CO2 (Carbon Dioxide)
The time rate of response for the current rise and fall

25. How many times per second does short circuiting take place?
20 to 200 times per second
V groove or U groove
(DCEP) Direct Current Electrode Positive or Reverse polarity
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

26. What is the key advantage of short circuiting transfer?
AWS and CSA
Minimum distortion due to low heat input
V groove or U groove
Wire feed speed - Voltage control

27. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
...
Shielding the molten weld metal from atmospheric contamination
Cause flaking - which can clog the liner and contact tube
Gas metal arc welding

28. List 3 wire drive systems and give a short description of each
To limit the short circuiting current so that spatter is reduced
Generally not as accurate
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

29. What is the recommended electrode stick- out for .035 solid wire?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
To prevent leakage - Carbon Dioxide (CO2)
1/4 inch to 1/2 inch
15 feet (4.5 meters)

30. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
Gives arc voltage values to the control system of the feeder
(DCEP) Direct Current Electrode Positive or Reverse polarity
Minutes of elapsed time continually run (out of 10 minutes)
Generally not as accurate

31. Give a brief description of the GMAW process
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
Welding process that joins metals by heating them with an electric arc
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

32. What type of power source is used with a constant speed wire feeder?
Pressure - The rate of flow of a shielding gas
Constant voltage (CV)
Welding process that joins metals by heating them with an electric arc
Motor driven generators - Transformer rectifiers - and Inverter designs

33. What current and polarity is generally used with GMAW?
The time rate of response for the current rise and fall
DCEP (Direct Current Electrode Positive) Reverse Polarity
3
Dry ice can form within the flow control openings and cause blockage of shielding gas

34. What does the wire feeder control?
5.8 to 12.5 L/min
12 to 22 arc volts
To prevent leakage - Carbon Dioxide (CO2)
Speed of the feed motor and - starting / stopping electrode feed

35. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
Puddle fluidity
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
...
Wire feeds smoothly (yet will slip should a problem occur in the gun)

36. List the basic equipment requirements for the GMAW process
(DCEP) Direct Current Electrode Positive or Reverse polarity
1/4 inch to 1/2 inch
Short- circuiting transfer - Globular transfer - Spray transfer
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

37. What is the purpose of the shielding gas used in GMAW?
The resistace to electrical current flow increases with it. Causing the electrode to heat
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Shielding the molten weld metal from atmospheric contamination
By there current carrying capacity

38. What is a solenoid valve and what actuates it?
To prevent drawing of liquid CO2 (Carbon Dioxide)
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Shielding the molten weld metal from atmospheric contamination
Insufficient current to melt the wire off cleanly

39. What controls amperage when using GMAW?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
To prevent leakage - Carbon Dioxide (CO2)
85%
Wire feed speed

40. What would be an indication that the drive roll pressure is adjusted correctly?
Minimum distortion due to low heat input
12 to 22 arc volts
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Gas metal arc welding

41. What is the maximum distance that hard wire can be successfully pushed?
Minimum distortion due to low heat input
Controls the rate of flow of a shielding gas to the gun nozzle
15 feet (4.5 meters)
Puddle fluidity

42. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Minutes of elapsed time continually run (out of 10 minutes)
Duty cycle
V groove or U groove
Wire feed speed - Voltage control

43. How are GMAW guns rated?
By there current carrying capacity
(DCEP) Direct Current Electrode Positive or Reverse polarity
The Arc voltage
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

44. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
85%
Cause flaking - which can clog the liner and contact tube
By there current carrying capacity
Aluminum wire

45. What does a flowmeter do and what does it measure?
To limit the short circuiting current so that spatter is reduced
These terms are quite restrictive and often technically incorrect
AWS and CSA
Controls the rate of flow of a shielding gas to the gun nozzle

46. When is the metal transferred with short circuit transfer?
1/4 inch to 1/2 inch
By there current carrying capacity
When the filler wire is in direct contract with the base metal
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

47. Why is globular transfer generally avoided with GMAW?
Spatter problems and poor weld appearance
Constant- speed wire feeders and Voltage- sennsing wire feeders
To prevent drawing of liquid CO2 (Carbon Dioxide)
5.8 to 12.5 L/min

48. What 2 organizations designate specifications for GMAW wires?
AWS and CSA
3
Aluminum wire
Guns

49. What is the effect of too much slope?
Insufficient current to melt the wire off cleanly
Constant- speed wire feeders and Voltage- sennsing wire feeders
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

50. What is the required arc voltage used for short circuit transfer?
Wire feed speed - Voltage control
Pressure - The rate of flow of a shielding gas
12 to 22 arc volts
5.8 to 12.5 L/min