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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 output on the welding machine is used to rate the duty cycle?
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Minutes of elapsed time continually run (out of 10 minutes)
5.8 to 12.5 L/min
Constant current (CC)

2. What happens when the electrode extension is increased?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
The resistace to electrical current flow increases with it. Causing the electrode to heat
Gas metal arc welding
Dry ice can form within the flow control openings and cause blockage of shielding gas

3. Why is the term GMAW preferred over MIG or MAG?
These terms are quite restrictive and often technically incorrect
Reducing the gas source pressure to a constant working pressure
Minimum distortion due to low heat input
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

4. What type of power source is commonly used with a voltage sensing wire feeder?
85%
Constant current (CC)
To prevent leakage - Carbon Dioxide (CO2)
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5. What is the required arc voltage used for short circuit transfer?
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Motor driven generators - Transformer rectifiers - and Inverter designs
Spatter problems and poor weld appearance
12 to 22 arc volts

6. List 3 wire drive systems and give a short description of each
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
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
12 to 22 arc volts
Controls the rate of flow of a shielding gas to the gun nozzle

7. Why must CO2 cylinders be used in the vertical position?
20 to 200 times per second
Insufficient current to melt the wire off cleanly
5.8 to 12.5 L/min
To prevent drawing of liquid CO2 (Carbon Dioxide)

8. What is the maximum distance that hard wire can be successfully pushed?
15 feet (4.5 meters)
Motor driven generators - Transformer rectifiers - and Inverter designs
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
20 to 200 times per second

9. What processes are constant current (CC) power sources designed to be used with?
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The Arc voltage
To prevent drawing of liquid CO2 (Carbon Dioxide)
SMAW - GTAW

10. What 2 controls are found on a GMAW set- up?
Wire feed speed
Shielding the molten weld metal from atmospheric contamination
SMAW - GTAW
Wire feed speed - Voltage control

11. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Aluminum wire
Reducing the gas source pressure to a constant working pressure
Gives arc voltage values to the control system of the feeder
The Arc voltage

12. What would be an indication that the drive roll pressure is adjusted correctly?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Wire feed speed
Penetration and burn - off rate of the electrode
Gives arc voltage values to the control system of the feeder

13. Why is globular transfer generally avoided with GMAW?
Spatter problems and poor weld appearance
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To limit the short circuiting current so that spatter is reduced
Minimum distortion due to low heat input

14. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
The negative side of a welding unit
Reducing the gas source pressure to a constant working pressure
Motor driven generators - Transformer rectifiers - and Inverter designs
...

15. What controls the wire speed on a voltage sensing wire feeder?
Minutes of elapsed time continually run (out of 10 minutes)
To prevent drawing of liquid CO2 (Carbon Dioxide)
These terms are quite restrictive and often technically incorrect
The Arc voltage

16. What type of power source is used with a constant speed wire feeder?
Generally not as accurate
Pressure vessels and the piping industry
Constant voltage (CV)
Puddle fluidity

17. What does the abbreviation NEMA stand for?
Gas metal arc welding
20 to 200 times per second
Minutes of elapsed time continually run (out of 10 minutes)
National Electrical Manufactures Association

18. List the factors that determine the mode of metal transfer
1/4 inch to 1/2 inch
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Voltage is the force that overcomes resistance to allow amperage flow

19. What is an advantage of pulsed arc transfer with GMAW?
By there current carrying capacity
20 to 200 times per second
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

20. Give a brief description of the GMAW process
SMAW - GTAW
The time rate of response for the current rise and fall
(DCEP) Direct Current Electrode Positive or Reverse polarity
Welding process that joins metals by heating them with an electric arc

21. What does a flowmeter do and what does it measure?
Minutes of elapsed time continually run (out of 10 minutes)
The resistace to electrical current flow increases with it. Causing the electrode to heat
Controls the rate of flow of a shielding gas to the gun nozzle
The time rate of response for the current rise and fall

22. With straight polarity where is 2/3 of the arc energy?
Aluminum wire
The Arc voltage
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
The negative side of a welding unit

23. What is the effect of too much slope?
Dry ice can form within the flow control openings and cause blockage of shielding gas
AWS and CSA
Insufficient current to melt the wire off cleanly
Controls the rate of flow of a shielding gas to the gun nozzle

24. What is the purpose of a regulator and what does it indicate on its gauges?
Dry ice can form within the flow control openings and cause blockage of shielding gas
Pressure - The rate of flow of a shielding gas
SMAW - GTAW
Reducing the gas source pressure to a constant working pressure

25. What is the main purpose of 'slope'?
Pressure - The rate of flow of a shielding gas
Wire feed speed
Penetration and burn - off rate of the electrode
To limit the short circuiting current so that spatter is reduced

26. What is another term for electrode holders for GMAW?
15 feet (4.5 meters)
Guns
Generally not as accurate
Motor driven generators - Transformer rectifiers - and Inverter designs

27. What controls amperage when using GMAW?
The Arc voltage
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Cause flaking - which can clog the liner and contact tube
Wire feed speed

28. What is the preferred drive roll design for solid wires?
Constant voltage (CV)
Spatter problems and poor weld appearance
V groove or U groove
Penetration and burn - off rate of the electrode

29. 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- speed wire feeders and Voltage- sennsing wire feeders
...
Insufficient current to melt the wire off cleanly

30. Why is a fiber washer required and what cylinder gas requires it?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
To prevent leakage - Carbon Dioxide (CO2)
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

31. A pull type drive system is usually used on what type of material?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Aluminum wire
3
SMAW - GTAW

32. How many times per second does short circuiting take place?
Welding process that joins metals by heating them with an electric arc
The negative side of a welding unit
20 to 200 times per second
Higher 26 to 35 arc volts

33. In the GMAW process what does amperage control?
Insufficient current to melt the wire off cleanly
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Penetration and burn - off rate of the electrode
Guns

34. What is the disadvantage of the gauge preset type of regulator/flowmeter?
3
These terms are quite restrictive and often technically incorrect
Aluminum wire
Generally not as accurate

35. What wire are knurled drive rolls most commonly used on?
Guns
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Flux cored wires
85%

36. What are the 2 types of wire feeders available?
Constant- speed wire feeders and Voltage- sennsing wire feeders
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Guns
Pressure vessels and the piping industry

37. Draw a typical volt amp curve for a machine that is designed for GMAW
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DCEP (Direct Current Electrode Positive) Reverse Polarity
15 feet (4.5 meters)
When the filler wire is in direct contract with the base metal

38. What 2 organizations designate specifications for GMAW wires?
Reducing the gas source pressure to a constant working pressure
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Duty cycle
AWS and CSA

39. When is the metal transferred with short circuit transfer?
National Electrical Manufactures Association
When the filler wire is in direct contract with the base metal
Aluminum wire
V groove or U groove

40. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
3
Cause flaking - which can clog the liner and contact tube
AWS and CSA

41. What current and polarity is generally used with GMAW?
Insufficient current to melt the wire off cleanly
Pressure - The rate of flow of a shielding gas
DCEP (Direct Current Electrode Positive) Reverse Polarity
If you dont know this check your phone

42. What does the term GMAW identify?
The resistace to electrical current flow increases with it. Causing the electrode to heat
Generally not as accurate
Gas metal arc welding
Pressure vessels and the piping industry

43. 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
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
To prevent drawing of liquid CO2 (Carbon Dioxide)
Duty cycle

44. What power sources are used with the GMAW Process?
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
Motor driven generators - Transformer rectifiers - and Inverter designs
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. Give a description of 'pinch effect'
85%
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
...
Guns

46. List the three methods of metal transfer with GMAW
Aluminum wire
Short- circuiting transfer - Globular transfer - Spray transfer
Constant voltage (CV)
85%

47. List several industries that would use GMAW
Pressure vessels and the piping industry
SMAW - GTAW
V groove or U groove
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

48. What is a solenoid valve and what actuates it?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
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
Gas metal arc welding
Speed of the feed motor and - starting / stopping electrode feed

49. What is the key advantage of short circuiting transfer?
National Electrical Manufactures Association
Minimum distortion due to low heat input
Dry ice can form within the flow control openings and cause blockage of shielding gas
Insufficient current to melt the wire off cleanly

50. What does inductance control?
Controls the rate of flow of a shielding gas to the gun nozzle
The Arc voltage
The time rate of response for the current rise and fall
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