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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. How are GMAW guns rated?
To prevent leakage - Carbon Dioxide (CO2)
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Constant voltage (CV)
By there current carrying capacity

2. What type of power source is commonly used with 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
The time rate of response for the current rise and fall
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
Constant current (CC)

3. 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
Motor driven generators - Transformer rectifiers - and Inverter designs
Duty cycle

4. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
85%
15 feet (4.5 meters)
Flux cored wires

5. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Guns
Penetration and burn - off rate of the electrode
Constant- speed wire feeders and Voltage- sennsing wire feeders
Higher 26 to 35 arc volts

6. List the three methods of metal transfer with GMAW
Wire feed speed - Voltage control
Insufficient current to melt the wire off cleanly
Speed of the feed motor and - starting / stopping electrode feed
Short- circuiting transfer - Globular transfer - Spray transfer

7. What is another term for electrode holders for GMAW?
Constant voltage (CV)
Gas metal arc welding
Guns
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

8. What output on the welding machine is used to rate the duty cycle?
Wire feed speed
The resistace to electrical current flow increases with it. Causing the electrode to heat
Minutes of elapsed time continually run (out of 10 minutes)
Motor driven generators - Transformer rectifiers - and Inverter designs

9. What does the term GMAW identify?
15 feet (4.5 meters)
V groove or U groove
Gas metal arc welding
Wire feed speed

10. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
Short- circuiting transfer - Globular transfer - Spray transfer
...
Minimum distortion due to low heat input
Constant voltage (CV)

11. What power sources are used with the GMAW Process?
Short- circuiting transfer - Globular transfer - Spray transfer
Welding process that joins metals by heating them with an electric arc
To prevent drawing of liquid CO2 (Carbon Dioxide)
Motor driven generators - Transformer rectifiers - and Inverter designs

12. List 3 wire drive systems and give a short description of each
When the filler wire is in direct contract with the base metal
By there current carrying capacity
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
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

13. What controls the wire speed on a voltage sensing wire feeder?
Insufficient current to melt the wire off cleanly
The Arc voltage
12 to 22 arc volts
Penetration and burn - off rate of the electrode

14. What does voltage do in an electrical circuit?
Pressure vessels and the piping industry
Generally not as accurate
Voltage is the force that overcomes resistance to allow amperage flow
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

15. What would be an indication that the drive roll pressure is adjusted correctly?
These terms are quite restrictive and often technically incorrect
To prevent leakage - Carbon Dioxide (CO2)
Gives arc voltage values to the control system of the feeder
Wire feeds smoothly (yet will slip should a problem occur in the gun)

16. What does a flowmeter do and what does it measure?
Aluminum wire
Controls the rate of flow of a shielding gas to the gun nozzle
Guns
Spatter problems and poor weld appearance

17. Why is a fiber washer required and what cylinder gas requires it?
15 feet (4.5 meters)
To prevent leakage - Carbon Dioxide (CO2)
Flux cored wires
Pressure - The rate of flow of a shielding gas

18. What does the abbreviation NEMA stand for?
Cause flaking - which can clog the liner and contact tube
Short- circuiting transfer - Globular transfer - Spray transfer
National Electrical Manufactures Association
To limit the short circuiting current so that spatter is reduced

19. What are the 2 types of wire feeders available?
Guns
Constant- speed wire feeders and Voltage- sennsing wire feeders
(DCEP) Direct Current Electrode Positive or Reverse polarity
Controls the rate of flow of a shielding gas to the gun nozzle

20. List the basic equipment requirements for the GMAW process
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Motor driven generators - Transformer rectifiers - and Inverter designs
20 to 200 times per second
By there current carrying capacity

21. What is an advantage of pulsed arc transfer with GMAW?
Constant- speed wire feeders and Voltage- sennsing wire feeders
Short- circuiting transfer - Globular transfer - Spray transfer
Pressure vessels and the piping industry
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

22. What effect does increasing and decreasing the inductance have on the weld?
20 to 200 times per second
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
AWS and CSA
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

23. In the GMAW process what does amperage control?
Wire feed speed
Penetration and burn - off rate of the electrode
The time rate of response for the current rise and fall
When the filler wire is in direct contract with the base metal

24. What is the effect of too much slope?
Wire feed speed - Voltage control
Higher 26 to 35 arc volts
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Insufficient current to melt the wire off cleanly

25. Draw a typical volt amp curve for a machine that is designed for GMAW
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To limit the short circuiting current so that spatter is reduced
Voltage is the force that overcomes resistance to allow amperage flow
Pressure - The rate of flow of a shielding gas

26. Regulators control_____________ flowmeters SHOW____________.
Welding process that joins metals by heating them with an electric arc
Duty cycle
Pressure - The rate of flow of a shielding gas
Short- circuiting transfer - Globular transfer - Spray transfer

27. What is a solenoid valve and what actuates it?
National Electrical Manufactures Association
The negative side of a welding unit
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Pressure vessels and the piping industry

28. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Flux cored wires
Duty cycle
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Gas metal arc welding

29. Why is globular transfer generally avoided with GMAW?
Duty cycle
Spatter problems and poor weld appearance
Welding process that joins metals by heating them with an electric arc
The negative side of a welding unit

30. What is the main purpose of 'slope'?
Cause flaking - which can clog the liner and contact tube
To limit the short circuiting current so that spatter is reduced
Minutes of elapsed time continually run (out of 10 minutes)
Guns

31. What processes are constant current (CC) power sources designed to be used with?
The resistace to electrical current flow increases with it. Causing the electrode to heat
SMAW - GTAW
Penetration and burn - off rate of the electrode
Speed of the feed motor and - starting / stopping electrode feed

32. What 2 organizations designate specifications for GMAW wires?
Cause flaking - which can clog the liner and contact tube
Welding process that joins metals by heating them with an electric arc
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
AWS and CSA

33. What does inductance control?
Pressure - The rate of flow of a shielding gas
If you dont know this check your phone
By there current carrying capacity
The time rate of response for the current rise and fall

34. With straight polarity where is 2/3 of the arc energy?
V groove or U groove
Welding process that joins metals by heating them with an electric arc
The negative side of a welding unit
Pressure - The rate of flow of a shielding gas

35. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
By there current carrying capacity
Cause flaking - which can clog the liner and contact tube
85%
Constant- speed wire feeders and Voltage- sennsing wire feeders

36. What is a typical flow rate of CO2 for short circuit transfer?
5.8 to 12.5 L/min
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Aluminum wire
AWS and CSA

37. What current and polarity is generally used with GMAW?
12 to 22 arc volts
By there current carrying capacity
DCEP (Direct Current Electrode Positive) Reverse Polarity
1/4 inch to 1/2 inch

38. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Generally not as accurate
To prevent drawing of liquid CO2 (Carbon Dioxide)
Reducing the gas source pressure to a constant working pressure
SMAW - GTAW

39. Why is a line heater required when using GMAW?
Controls the rate of flow of a shielding gas to the gun nozzle
Constant current (CC)
Dry ice can form within the flow control openings and cause blockage of shielding gas
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40. In the GMAW process what does voltage control?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Puddle fluidity
Constant- speed wire feeders and Voltage- sennsing wire feeders
Reducing the gas source pressure to a constant working pressure

41. What 2 controls are found on a GMAW set- up?
Wire feed speed - Voltage control
Controls the rate of flow of a shielding gas to the gun nozzle
Dry ice can form within the flow control openings and cause blockage of shielding gas
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

42. 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
Short- circuiting transfer - Globular transfer - Spray transfer
Reducing the gas source pressure to a constant working pressure
Minutes of elapsed time continually run (out of 10 minutes)

43. What is the preferred drive roll design for solid wires?
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
These terms are quite restrictive and often technically incorrect
Dry ice can form within the flow control openings and cause blockage of shielding gas
V groove or U groove

44. What is the key advantage of short circuiting transfer?
Minimum distortion due to low heat input
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
To prevent leakage - Carbon Dioxide (CO2)

45. Why is the term GMAW preferred over MIG or MAG?
These terms are quite restrictive and often technically incorrect
Guns
Gas metal arc welding
AWS and CSA

46. What happens when the electrode extension is increased?
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
The resistace to electrical current flow increases with it. Causing the electrode to heat
1/4 inch to 1/2 inch
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

47. Why must CO2 cylinders be used in the vertical position?
To prevent drawing of liquid CO2 (Carbon Dioxide)
Penetration and burn - off rate of the electrode
By there current carrying capacity
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

48. What does the wire feeder control?
Dry ice can form within the flow control openings and cause blockage of shielding gas
Spatter problems and poor weld appearance
Speed of the feed motor and - starting / stopping electrode feed
Constant current (CC)

49. A pull type drive system is usually used on what type of material?
3
Controls the rate of flow of a shielding gas to the gun nozzle
Aluminum wire
To prevent leakage - Carbon Dioxide (CO2)

50. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
Shielding the molten weld metal from atmospheric contamination
15 feet (4.5 meters)
Pressure vessels and the piping industry
If you dont know this check your phone