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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. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
(DCEP) Direct Current Electrode Positive or Reverse polarity
Puddle fluidity
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1/4 inch to 1/2 inch

2. What is the key advantage of short circuiting transfer?
Minimum distortion due to low heat input
Pressure - The rate of flow of a shielding gas
Minutes of elapsed time continually run (out of 10 minutes)
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. In the GMAW process what does amperage control?
Constant voltage (CV)
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Penetration and burn - off rate of the electrode
By there current carrying capacity

4. What type of power source is used with a constant speed wire feeder?
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Pressure vessels and the piping industry
Constant voltage (CV)
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5. What is a typical flow rate of CO2 for short circuit transfer?
When the filler wire is in direct contract with the base metal
Welding process that joins metals by heating them with an electric arc
Guns
5.8 to 12.5 L/min

6. Why is a fiber washer required and what cylinder gas requires it?
AWS and CSA
Generally not as accurate
To prevent leakage - Carbon Dioxide (CO2)
These terms are quite restrictive and often technically incorrect

7. What is the purpose of the shielding gas used in GMAW?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Constant current (CC)
Shielding the molten weld metal from atmospheric contamination
V groove or U groove

8. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
The negative side of a welding unit
Gives arc voltage values to the control system of the feeder
Speed of the feed motor and - starting / stopping electrode feed
Duty cycle

9. What current and polarity is generally used with GMAW?
Gives arc voltage values to the control system of the feeder
Pressure - The rate of flow of a shielding gas
Guns
DCEP (Direct Current Electrode Positive) Reverse Polarity

10. List the three methods of metal transfer with GMAW
Duty cycle
Pressure vessels and the piping industry
Short- circuiting transfer - Globular transfer - Spray transfer
Motor driven generators - Transformer rectifiers - and Inverter designs

11. Why must CO2 cylinders be used in the vertical position?
Constant voltage (CV)
Speed of the feed motor and - starting / stopping electrode feed
To prevent drawing of liquid CO2 (Carbon Dioxide)
Puddle fluidity

12. What type of power source is commonly used with a voltage sensing wire feeder?
The resistace to electrical current flow increases with it. Causing the electrode to heat
Minutes of elapsed time continually run (out of 10 minutes)
Constant current (CC)
5.8 to 12.5 L/min

13. What is a solenoid valve and what actuates it?
Penetration and burn - off rate of the electrode
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Flux cored wires

14. List the factors that determine the mode of metal transfer
The negative side of a welding unit
Flux cored wires
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Insufficient current to melt the wire off cleanly

15. What is the maximum distance that hard wire can be successfully pushed?
Motor driven generators - Transformer rectifiers - and Inverter designs
AWS and CSA
Gives arc voltage values to the control system of the feeder
15 feet (4.5 meters)

16. What 2 organizations designate specifications for GMAW 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
AWS and CSA
Voltage is the force that overcomes resistance to allow amperage flow
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17. List the basic equipment requirements for the GMAW process
85%
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Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Reducing the gas source pressure to a constant working pressure

18. Why is the term GMAW preferred over MIG or MAG?
Voltage is the force that overcomes resistance to allow amperage flow
These terms are quite restrictive and often technically incorrect
To limit the short circuiting current so that spatter is reduced
The time rate of response for the current rise and fall

19. What power sources are used with the GMAW Process?
Motor driven generators - Transformer rectifiers - and Inverter designs
When the filler wire is in direct contract with the base metal
85%
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

20. A pull type drive system is usually used on what type of material?
Aluminum wire
12 to 22 arc volts
To limit the short circuiting current so that spatter is reduced
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21. What does the abbreviation NEMA stand for?
Duty cycle
Pressure vessels and the piping industry
SMAW - GTAW
National Electrical Manufactures Association

22. List several industries that would use GMAW
85%
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
The time rate of response for the current rise and fall

23. What are the 2 types of wire feeders available?
Constant- speed wire feeders and Voltage- sennsing wire feeders
V groove or U groove
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Aluminum wire

24. What does inductance control?
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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
Voltage is the force that overcomes resistance to allow amperage flow
The time rate of response for the current rise and fall

25. In the GMAW process what does voltage control?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Voltage is the force that overcomes resistance to allow amperage flow
Puddle fluidity
Wire feed speed - Voltage control

26. What would be an indication that the drive roll pressure is adjusted correctly?
Welding process that joins metals by heating them with an electric arc
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

27. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
Generally not as accurate
85%
20 to 200 times per second
Spatter problems and poor weld appearance

28. What is the main purpose of 'slope'?
To limit the short circuiting current so that spatter is reduced
Reducing the gas source pressure to a constant working pressure
Gas metal arc welding
Generally not as accurate

29. When is the metal transferred with short circuit transfer?
Motor driven generators - Transformer rectifiers - and Inverter designs
When the filler wire is in direct contract with the base metal
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
15 feet (4.5 meters)

30. What is another term for electrode holders for GMAW?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Wire feed speed - Voltage control
Guns
15 feet (4.5 meters)

31. What 2 controls are found on a GMAW set- up?
The negative side of a welding unit
Wire feed speed - Voltage control
National Electrical Manufactures Association
15 feet (4.5 meters)

32. What is the recommended electrode stick- out for .035 solid wire?
1/4 inch to 1/2 inch
Guns
Pressure vessels and the piping industry
By there current carrying capacity

33. Give a description of 'pinch effect'
5.8 to 12.5 L/min
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
These terms are quite restrictive and often technically incorrect
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

34. Why is globular transfer generally avoided with GMAW?
1/4 inch to 1/2 inch
Duty cycle
Spatter problems and poor weld appearance
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

35. What effect does increasing and decreasing the inductance have on the weld?
20 to 200 times per second
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
Constant- speed wire feeders and Voltage- sennsing wire feeders

36. What controls amperage when using GMAW?
Wire feed speed
To prevent drawing of liquid CO2 (Carbon Dioxide)
...
Minutes of elapsed time continually run (out of 10 minutes)

37. What output on the welding machine is used to rate the duty cycle?
SMAW - GTAW
Minutes of elapsed time continually run (out of 10 minutes)
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
The negative side of a welding unit

38. List 3 wire drive systems and give a short description of each
To limit the short circuiting current so that spatter is reduced
Constant voltage (CV)
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

39. List 3 forms compressed gases may be supplied for welding
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
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

40. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Reducing the gas source pressure to a constant working pressure
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
These terms are quite restrictive and often technically incorrect
Higher 26 to 35 arc volts

41. What is an advantage of pulsed arc transfer with GMAW?
Pressure - The rate of flow of a shielding gas
Controls the rate of flow of a shielding gas to the gun nozzle
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Generally not as accurate

42. What does voltage do in an electrical circuit?
Voltage is the force that overcomes resistance to allow amperage flow
Speed of the feed motor and - starting / stopping electrode feed
Gives arc voltage values to the control system of the feeder
Motor driven generators - Transformer rectifiers - and Inverter designs

43. What is the preferred drive roll design for solid wires?
Short- circuiting transfer - Globular transfer - Spray transfer
V groove or U groove
Pressure - The rate of flow of a shielding gas
Generally not as accurate

44. What does the wire feeder control?
Speed of the feed motor and - starting / stopping electrode feed
85%
Wire feed speed
Constant current (CC)

45. What is the purpose of a regulator and what does it indicate on its gauges?
Guns
Dry ice can form within the flow control openings and cause blockage of shielding gas
Reducing the gas source pressure to a constant working pressure
Constant voltage (CV)

46. What is the effect of too much slope?
The time rate of response for the current rise and fall
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Insufficient current to melt the wire off cleanly
15 feet (4.5 meters)

47. What controls the wire speed on a voltage sensing wire feeder?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
The resistace to electrical current flow increases with it. Causing the electrode to heat
The Arc voltage
V groove or U groove

48. What processes are constant current (CC) power sources designed to be used with?
Duty cycle
SMAW - GTAW
DCEP (Direct Current Electrode Positive) Reverse Polarity
If you dont know this check your phone

49. What is the required arc voltage used for short circuit transfer?
12 to 22 arc volts
Generally not as accurate
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

50. With straight polarity where is 2/3 of the arc energy?
The negative side of a welding unit
To prevent drawing of liquid CO2 (Carbon Dioxide)
15 feet (4.5 meters)
Guns