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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 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
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
12 to 22 arc volts
Short- circuiting transfer - Globular transfer - Spray transfer

2. What happens when the electrode extension is increased?
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
By there current carrying capacity
The resistace to electrical current flow increases with it. Causing the electrode to heat
Aluminum wire

3. What is the key advantage of short circuiting transfer?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
3
Minimum distortion due to low heat input
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4. Why is globular transfer generally avoided with GMAW?
3
1/4 inch to 1/2 inch
Spatter problems and poor weld appearance
12 to 22 arc volts

5. What is the purpose of the shielding gas used in GMAW?
Duty cycle
Shielding the molten weld metal from atmospheric contamination
20 to 200 times per second
Short- circuiting transfer - Globular transfer - Spray transfer

6. What type of power source is used with a constant speed wire feeder?
Minimum distortion due to low heat input
Spatter problems and poor weld appearance
Controls the rate of flow of a shielding gas to the gun nozzle
Constant voltage (CV)

7. What is the maximum distance that hard wire can be successfully pushed?
Minutes of elapsed time continually run (out of 10 minutes)
Constant voltage (CV)
15 feet (4.5 meters)
Flux cored wires

8. In the GMAW process what does amperage control?
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Penetration and burn - off rate of the electrode
Pressure vessels and the piping industry
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

9. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
Aluminum wire
SMAW - GTAW
Wire feeds smoothly (yet will slip should a problem occur in the gun)
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10. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
85%
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Spatter problems and poor weld appearance
DCEP (Direct Current Electrode Positive) Reverse Polarity

11. In the GMAW process what does voltage control?
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
Puddle fluidity
Higher 26 to 35 arc volts

12. List several industries that would use GMAW
By there current carrying capacity
Puddle fluidity
Pressure vessels and the piping industry
Constant voltage (CV)

13. Draw a typical volt amp curve for a machine that is designed for GMAW
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Gives arc voltage values to the control system of the feeder
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Constant voltage (CV)

14. Give a description of 'pinch effect'
By there current carrying capacity
Minutes of elapsed time continually run (out of 10 minutes)
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Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

15. Why is a line heater required when using GMAW?
Dry ice can form within the flow control openings and cause blockage of shielding gas
National Electrical Manufactures Association
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Cause flaking - which can clog the liner and contact tube

16. What does voltage do in an electrical circuit?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
15 feet (4.5 meters)
Voltage is the force that overcomes resistance to allow amperage flow
Speed of the feed motor and - starting / stopping electrode feed

17. What is the required arc voltage used for short circuit transfer?
Constant- speed wire feeders and Voltage- sennsing wire feeders
To prevent leakage - Carbon Dioxide (CO2)
12 to 22 arc volts
SMAW - GTAW

18. Why is the term GMAW preferred over MIG or MAG?
These terms are quite restrictive and often technically incorrect
National Electrical Manufactures Association
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Constant- speed wire feeders and Voltage- sennsing wire feeders

19. What is the recommended electrode stick- out for .035 solid wire?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Cause flaking - which can clog the liner and contact tube
1/4 inch to 1/2 inch
Wire feeds smoothly (yet will slip should a problem occur in the gun)

20. What are the 2 types of wire feeders available?
...
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Flux cored wires
Constant- speed wire feeders and Voltage- sennsing wire feeders

21. What is the effect of too much slope?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Guns
Insufficient current to melt the wire off cleanly
3

22. What wire are knurled drive rolls most commonly used on?
Flux cored wires
Constant voltage (CV)
Speed of the feed motor and - starting / stopping electrode feed
Penetration and burn - off rate of the electrode

23. How many times per second does short circuiting take place?
Minimum distortion due to low heat input
Motor driven generators - Transformer rectifiers - and Inverter designs
20 to 200 times per second
AWS and CSA

24. What type of power source is commonly used with a voltage sensing wire feeder?
The negative side of a welding unit
V groove or U groove
Constant current (CC)
Insufficient current to melt the wire off cleanly

25. List the basic equipment requirements for the GMAW process
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
Gives arc voltage values to the control system of the feeder
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

26. What does a flowmeter do and what does it measure?
Reducing the gas source pressure to a constant working pressure
Higher 26 to 35 arc volts
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Controls the rate of flow of a shielding gas to the gun nozzle

27. What is the preferred drive roll design for solid wires?
To prevent drawing of liquid CO2 (Carbon Dioxide)
Duty cycle
V groove or U groove
SMAW - GTAW

28. What processes are constant current (CC) power sources designed to be used with?
Pressure vessels and the piping industry
SMAW - GTAW
Reducing the gas source pressure to a constant working pressure
Shielding the molten weld metal from atmospheric contamination

29. What does the abbreviation NEMA stand for?
Voltage is the force that overcomes resistance to allow amperage flow
National Electrical Manufactures Association
AWS and CSA
85%

30. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Insufficient current to melt the wire off cleanly
Welding process that joins metals by heating them with an electric arc
Wire feed speed - Voltage control
Generally not as accurate

31. What current and polarity is generally used with GMAW?
Reducing the gas source pressure to a constant working pressure
DCEP (Direct Current Electrode Positive) Reverse Polarity
(DCEP) Direct Current Electrode Positive or Reverse polarity
Penetration and burn - off rate of the electrode

32. Why is a fiber washer required and what cylinder gas requires it?
Dry ice can form within the flow control openings and cause blockage of shielding gas
The time rate of response for the current rise and fall
To prevent leakage - Carbon Dioxide (CO2)
Generally not as accurate

33. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Cause flaking - which can clog the liner and contact tube
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
If you dont know this check your phone

34. What is a typical flow rate of CO2 for short circuit transfer?
5.8 to 12.5 L/min
Higher 26 to 35 arc volts
To prevent leakage - Carbon Dioxide (CO2)
Motor driven generators - Transformer rectifiers - and Inverter designs

35. 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)
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Gas metal arc welding
Welding process that joins metals by heating them with an electric arc

36. List 3 forms compressed gases may be supplied for welding
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
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Constant voltage (CV)
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

37. With straight polarity where is 2/3 of the arc energy?
V groove or U groove
The negative side of a welding unit
Gives arc voltage values to the control system of the feeder
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

38. A pull type drive system is usually used on what type of material?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Aluminum wire
Cause flaking - which can clog the liner and contact tube
National Electrical Manufactures Association

39. What power sources are used with the GMAW Process?
SMAW - GTAW
Flux cored wires
Motor driven generators - Transformer rectifiers - and Inverter designs
Constant voltage (CV)

40. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Duty cycle
National Electrical Manufactures Association
Aluminum wire
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

41. List 3 wire drive systems and give a short description of each
To limit the short circuiting current so that spatter is reduced
AWS and CSA
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
National Electrical Manufactures Association

42. 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
20 to 200 times per second
12 to 22 arc volts

43. How are GMAW guns rated?
Wire feed speed
By there current carrying capacity
Minutes of elapsed time continually run (out of 10 minutes)
...

44. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Dry ice can form within the flow control openings and cause blockage of shielding gas
To prevent drawing of liquid CO2 (Carbon Dioxide)
...
Higher 26 to 35 arc volts

45. What is the main purpose of 'slope'?
Duty cycle
Pressure vessels and the piping industry
To limit the short circuiting current so that spatter is reduced
...

46. What 2 controls are found on a GMAW set- up?
Minutes of elapsed time continually run (out of 10 minutes)
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
Constant current (CC)

47. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
To limit the short circuiting current so that spatter is reduced
If you dont know this check your phone
DCEP (Direct Current Electrode Positive) Reverse Polarity
3

48. What does the wire feeder control?
Duty cycle
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
Speed of the feed motor and - starting / stopping electrode feed

49. What output on the welding machine is used to rate the duty cycle?
Constant current (CC)
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 feed speed - Voltage control
Minutes of elapsed time continually run (out of 10 minutes)

50. What is the purpose of a regulator and what does it indicate on its gauges?
SMAW - GTAW
Reducing the gas source pressure to a constant working pressure
If you dont know this check your phone
12 to 22 arc volts