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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. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Higher 26 to 35 arc volts
12 to 22 arc volts
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
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

2. What type of power source is used with a constant speed wire feeder?
Controls the rate of flow of a shielding gas to the gun nozzle
Constant voltage (CV)
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

3. What is a typical flow rate of CO2 for short circuit transfer?
Gas metal arc welding
V groove or U groove
5.8 to 12.5 L/min
To prevent leakage - Carbon Dioxide (CO2)

4. When is the metal transferred with short circuit transfer?
When the filler wire is in direct contract with the base metal
Aluminum wire
Insufficient current to melt the wire off cleanly
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

5. Why is a fiber washer required and what cylinder gas requires it?
Higher 26 to 35 arc volts
To prevent leakage - Carbon Dioxide (CO2)
To prevent drawing of liquid CO2 (Carbon Dioxide)
DCEP (Direct Current Electrode Positive) Reverse Polarity

6. 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
Insufficient current to melt the wire off cleanly
The resistace to electrical current flow increases with it. Causing the electrode to heat

7. What does the wire feeder control?
Controls the rate of flow of a shielding gas to the gun nozzle
These terms are quite restrictive and often technically incorrect
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Speed of the feed motor and - starting / stopping electrode feed

8. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
3
The time rate of response for the current rise and fall
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Puddle fluidity

9. What is the purpose of the shielding gas used in GMAW?
Controls the rate of flow of a shielding gas to the gun nozzle
Shielding the molten weld metal from atmospheric contamination
Pressure - The rate of flow of a shielding gas
Pressure vessels and the piping industry

10. What wire are knurled drive rolls most commonly used on?
1/4 inch to 1/2 inch
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
The time rate of response for the current rise and fall
Flux cored wires

11. What power sources are used with the GMAW Process?
(DCEP) Direct Current Electrode Positive or Reverse polarity
Motor driven generators - Transformer rectifiers - and Inverter designs
To prevent drawing of liquid CO2 (Carbon Dioxide)
Welding process that joins metals by heating them with an electric arc

12. List the three methods of metal transfer with GMAW
Pressure - The rate of flow of a shielding gas
Short- circuiting transfer - Globular transfer - Spray transfer
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These terms are quite restrictive and often technically incorrect

13. What is the effect of too much slope?
Insufficient current to melt the wire off cleanly
Duty cycle
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Dry ice can form within the flow control openings and cause blockage of shielding gas

14. What processes are constant current (CC) power sources designed to be used with?
Controls the rate of flow of a shielding gas to the gun nozzle
Penetration and burn - off rate of the electrode
SMAW - GTAW
...

15. Draw a typical volt amp curve for a machine that is designed for GMAW
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
If you dont know this check your phone
Cause flaking - which can clog the liner and contact tube
1/4 inch to 1/2 inch

16. What controls amperage when using GMAW?
5.8 to 12.5 L/min
Duty cycle
Wire feed speed
...

17. What is the key advantage of short circuiting transfer?
Dry ice can form within the flow control openings and cause blockage of shielding gas
Minutes of elapsed time continually run (out of 10 minutes)
20 to 200 times per second
Minimum distortion due to low heat input

18. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
12 to 22 arc volts
Gives arc voltage values to the control system of the feeder
Puddle fluidity

19. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
National Electrical Manufactures Association
Wire feed speed - Voltage control
Cause flaking - which can clog the liner and contact tube
Generally not as accurate

20. What is the purpose of a regulator and what does it indicate on its gauges?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Duty cycle
Reducing the gas source pressure to a constant working pressure
Cause flaking - which can clog the liner and contact tube

21. What is the disadvantage of the gauge preset type of regulator/flowmeter?
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Constant voltage (CV)
When the filler wire is in direct contract with the base metal
Generally not as accurate

22. In the GMAW process what does voltage control?
Flux cored wires
SMAW - GTAW
Controls the rate of flow of a shielding gas to the gun nozzle
Puddle fluidity

23. What is an advantage of pulsed arc transfer with GMAW?
Welding process that joins metals by heating them with an electric arc
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
The time rate of response for the current rise and fall

24. With straight polarity where is 2/3 of the arc energy?
The negative side of a welding unit
Constant voltage (CV)
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Gas metal arc welding

25. What does the abbreviation NEMA stand for?
By there current carrying capacity
Cause flaking - which can clog the liner and contact tube
National Electrical Manufactures Association
If you dont know this check your phone

26. What effect does increasing and decreasing the inductance have on the weld?
Constant current (CC)
Insufficient current to melt the wire off cleanly
To limit the short circuiting current so that spatter is reduced
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

27. What is the main purpose of 'slope'?
To limit the short circuiting current so that spatter is reduced
1/4 inch to 1/2 inch
Shielding the molten weld metal from atmospheric contamination
Constant- speed wire feeders and Voltage- sennsing wire feeders

28. List 3 wire drive systems and give a short description of each
Minutes of elapsed time continually run (out of 10 minutes)
SMAW - GTAW
If you dont know this check your phone
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

29. What current and polarity is generally used with GMAW?
Higher 26 to 35 arc volts
Aluminum wire
The resistace to electrical current flow increases with it. Causing the electrode to heat
DCEP (Direct Current Electrode Positive) Reverse Polarity

30. Give a brief description of the GMAW process
Welding process that joins metals by heating them with an electric arc
Dry ice can form within the flow control openings and cause blockage of shielding gas
Pressure - The rate of flow of a shielding gas
Controls the rate of flow of a shielding gas to the gun nozzle

31. What controls the wire speed on a voltage sensing wire feeder?
The Arc voltage
Constant- speed wire feeders and Voltage- sennsing wire feeders
Spatter problems and poor weld appearance
If you dont know this check your phone

32. What 2 organizations designate specifications for GMAW wires?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Aluminum wire
AWS and CSA
To prevent leakage - Carbon Dioxide (CO2)

33. Regulators control_____________ flowmeters SHOW____________.
Dry ice can form within the flow control openings and cause blockage of shielding gas
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Pressure - The rate of flow of a shielding gas
Cause flaking - which can clog the liner and contact tube

34. How many times per second does short circuiting take place?
V groove or U groove
20 to 200 times per second
Pressure vessels and the piping industry
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

35. Why must CO2 cylinders be used in the vertical position?
Welding process that joins metals by heating them with an electric arc
To prevent drawing of liquid CO2 (Carbon Dioxide)
Penetration and burn - off rate of the electrode
Constant- speed wire feeders and Voltage- sennsing wire feeders

36. What is the recommended electrode stick- out for .035 solid wire?
1/4 inch to 1/2 inch
Constant voltage (CV)
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

37. In the GMAW process what does amperage control?
Flux cored wires
To prevent drawing of liquid CO2 (Carbon Dioxide)
Penetration and burn - off rate of the electrode
Constant voltage (CV)

38. List several industries that would use GMAW
Minimum distortion due to low heat input
Pressure vessels and the piping industry
Aluminum wire
Welding process that joins metals by heating them with an electric arc

39. What is a solenoid valve and what actuates 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
Short- circuiting transfer - Globular transfer - Spray transfer
Speed of the feed motor and - starting / stopping electrode feed

40. List the basic equipment requirements for the GMAW process
To prevent leakage - Carbon Dioxide (CO2)
...
By there current carrying capacity
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

41. What is the required arc voltage used for short circuit transfer?
The negative side of a welding unit
Speed of the feed motor and - starting / stopping electrode feed
The Arc voltage
12 to 22 arc volts

42. 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
Duty cycle
Shielding the molten weld metal from atmospheric contamination
Guns

43. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
85%
Flux cored wires
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
To limit the short circuiting current so that spatter is reduced

44. Give a description of 'pinch effect'
Motor driven generators - Transformer rectifiers - and Inverter designs
Penetration and burn - off rate of the electrode
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

45. Why is a line heater required when using GMAW?
Dry ice can form within the flow control openings and cause blockage of shielding gas
1/4 inch to 1/2 inch
Gas metal arc welding
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

46. Why is globular transfer generally avoided with GMAW?
Minimum distortion due to low heat input
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
Spatter problems and poor weld appearance

47. What output on the welding machine is used to rate the duty cycle?
Minutes of elapsed time continually run (out of 10 minutes)
Wire feed speed
National Electrical Manufactures Association
Penetration and burn - off rate of the electrode

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

49. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
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V groove or U groove
Gives arc voltage values to the control system of the feeder
Flux cored wires

50. What does the term GMAW identify?
...
National Electrical Manufactures Association
Gas metal arc welding
Dry ice can form within the flow control openings and cause blockage of shielding gas