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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.
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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 reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
By there current carrying capacity
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
12 to 22 arc volts
...

2. In the GMAW process what does amperage control?
Pressure - The rate of flow of a shielding gas
Penetration and burn - off rate of the electrode
Shielding the molten weld metal from atmospheric contamination
The Arc voltage

3. What processes are constant current (CC) power sources designed to be used with?
SMAW - GTAW
Duty cycle
Constant- speed wire feeders and Voltage- sennsing wire feeders
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

4. What controls amperage when using GMAW?
Higher 26 to 35 arc volts
Wire feed speed
When the filler wire is in direct contract with the base metal
Duty cycle

5. What controls the wire speed on a voltage sensing wire feeder?
Voltage is the force that overcomes resistance to allow amperage flow
If you dont know this check your phone
The Arc voltage
Dry ice can form within the flow control openings and cause blockage of shielding gas

6. What type of power source is commonly used with a voltage sensing wire feeder?
Shielding the molten weld metal from atmospheric contamination
Constant current (CC)
Insufficient current to melt the wire off cleanly
Welding process that joins metals by heating them with an electric arc

7. Why is a fiber washer required and what cylinder gas requires it?
Motor driven generators - Transformer rectifiers - and Inverter designs
To prevent leakage - Carbon Dioxide (CO2)
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Minutes of elapsed time continually run (out of 10 minutes)

8. What power sources are used with the GMAW Process?
Spatter problems and poor weld appearance
To limit the short circuiting current so that spatter is reduced
Motor driven generators - Transformer rectifiers - and Inverter designs
3

9. What is the preferred drive roll design for solid wires?
Generally not as accurate
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
Pressure - The rate of flow of a shielding gas

10. What is the effect of too much slope?
Insufficient current to melt the wire off cleanly
Spatter problems and poor weld appearance
Pressure - The rate of flow of a shielding gas
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

11. 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
Minutes of elapsed time continually run (out of 10 minutes)
These terms are quite restrictive and often technically incorrect
If you dont know this check your phone

12. What is the key advantage of short circuiting transfer?
Wire feed speed - Voltage control
Motor driven generators - Transformer rectifiers - and Inverter designs
Minimum distortion due to low heat input
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

13. What happens when the electrode extension is increased?
...
5.8 to 12.5 L/min
DCEP (Direct Current Electrode Positive) Reverse Polarity
The resistace to electrical current flow increases with it. Causing the electrode to heat

14. What is the maximum distance that hard wire can be successfully pushed?
Gives arc voltage values to the control system of the feeder
15 feet (4.5 meters)
3
Generally not as accurate

15. In the GMAW process what does voltage control?
To limit the short circuiting current so that spatter is reduced
Duty cycle
Puddle fluidity
Pressure vessels and the piping industry

16. Give a brief description of the GMAW process
Welding process that joins metals by heating them with an electric arc
Pressure vessels and the piping industry
Short- circuiting transfer - Globular transfer - Spray transfer
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

17. When is the metal transferred with short circuit transfer?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
When the filler wire is in direct contract with the base metal
3
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

18. What current and polarity is generally used with GMAW?
DCEP (Direct Current Electrode Positive) Reverse Polarity
...
Flux cored wires
Wire feed speed - Voltage control

19. What is an advantage of pulsed arc transfer with GMAW?
Flux cored wires
Gas metal arc welding
Spatter problems and poor weld appearance
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

20. Regulators control_____________ flowmeters SHOW____________.
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Aluminum wire
5.8 to 12.5 L/min
Pressure - The rate of flow of a shielding gas

21. What would be an indication that the drive roll pressure is adjusted correctly?
Minutes of elapsed time continually run (out of 10 minutes)
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Pressure vessels and the piping industry
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

22. What does the abbreviation NEMA stand for?
National Electrical Manufactures Association
Spatter problems and poor weld appearance
Pressure - The rate of flow of a shielding gas
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

23. What output on the welding machine is used to rate the duty cycle?
Spatter problems and poor weld appearance
Guns
Minutes of elapsed time continually run (out of 10 minutes)
The resistace to electrical current flow increases with it. Causing the electrode to heat

24. 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
Constant voltage (CV)
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Generally not as accurate

25. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
By there current carrying capacity
Voltage is the force that overcomes resistance to allow amperage flow
To prevent leakage - Carbon Dioxide (CO2)
85%

26. Why is globular transfer generally avoided with GMAW?
Spatter problems and poor weld appearance
The Arc voltage
Welding process that joins metals by heating them with an electric arc
Duty cycle

27. How are GMAW guns rated?
Gas metal arc welding
By there current carrying capacity
20 to 200 times per second
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28. Why is a line heater required when using GMAW?
Constant voltage (CV)
If you dont know this check your phone
The negative side of a welding unit
Dry ice can form within the flow control openings and cause blockage of shielding gas

29. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
DCEP (Direct Current Electrode Positive) Reverse Polarity
National Electrical Manufactures Association
If you dont know this check your phone
Minutes of elapsed time continually run (out of 10 minutes)

30. What is the required arc voltage used for short circuit transfer?
12 to 22 arc volts
By there current carrying capacity
The time rate of response for the current rise and fall
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

31. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
3
By there current carrying capacity
Motor driven generators - Transformer rectifiers - and Inverter designs
AWS and CSA

32. Why is the term GMAW preferred over MIG or MAG?
Puddle fluidity
These terms are quite restrictive and often technically incorrect
3
Spatter problems and poor weld appearance

33. List several industries that would use GMAW
Wire feed speed
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Pressure vessels and the piping industry
20 to 200 times per second

34. What is a solenoid valve and what actuates it?
AWS and CSA
The Arc voltage
National Electrical Manufactures Association
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

35. List 3 wire drive systems and give a short description of each
Voltage is the force that overcomes resistance to allow amperage flow
Minimum distortion due to low heat input
Gas metal arc welding
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

36. What is the purpose of the shielding gas used in GMAW?
Guns
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
1/4 inch to 1/2 inch
Shielding the molten weld metal from atmospheric contamination

37. What is the purpose of a regulator and what does it indicate on its gauges?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Reducing the gas source pressure to a constant working pressure
V groove or U groove
15 feet (4.5 meters)

38. What are the 2 types of wire feeders available?
Motor driven generators - Transformer rectifiers - and Inverter designs
Cause flaking - which can clog the liner and contact tube
Constant- speed wire feeders and Voltage- sennsing wire feeders
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

39. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Controls the rate of flow of a shielding gas to the gun nozzle
1/4 inch to 1/2 inch
Cause flaking - which can clog the liner and contact tube
AWS and CSA

40. What does the wire feeder control?
Generally not as accurate
Minutes of elapsed time continually run (out of 10 minutes)
Speed of the feed motor and - starting / stopping electrode feed
Controls the rate of flow of a shielding gas to the gun nozzle

41. Give a description of 'pinch effect'
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
To prevent drawing of liquid CO2 (Carbon Dioxide)
1/4 inch to 1/2 inch
15 feet (4.5 meters)

42. What does inductance control?
Motor driven generators - Transformer rectifiers - and Inverter designs
The time rate of response for the current rise and fall
The resistace to electrical current flow increases with it. Causing the electrode to heat
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

43. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Wire feed speed - Voltage control
20 to 200 times per second
The Arc voltage
Higher 26 to 35 arc volts

44. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Duty cycle
Dry ice can form within the flow control openings and cause blockage of shielding gas
Shielding the molten weld metal from atmospheric contamination
To limit the short circuiting current so that spatter is reduced

45. What does the term GMAW identify?
20 to 200 times per second
AWS and CSA
Gas metal arc welding
Aluminum wire

46. What wire are knurled drive rolls most commonly used on?
To prevent leakage - Carbon Dioxide (CO2)
Flux cored wires
Constant current (CC)
Voltage is the force that overcomes resistance to allow amperage flow

47. How many times per second does short circuiting take place?
85%
Cause flaking - which can clog the liner and contact tube
Insufficient current to melt the wire off cleanly
20 to 200 times per second

48. What is another term for electrode holders for GMAW?
V groove or U groove
Motor driven generators - Transformer rectifiers - and Inverter designs
Guns
Shielding the molten weld metal from atmospheric contamination

49. What type of power source is used with a constant speed wire feeder?
Constant voltage (CV)
3
...
Pressure - The rate of flow of a shielding gas

50. Why must CO2 cylinders be used in the vertical position?
AWS and CSA
12 to 22 arc volts
To prevent drawing of liquid CO2 (Carbon Dioxide)
Minimum distortion due to low heat input