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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. List 3 forms compressed gases may be supplied for welding
Dry ice can form within the flow control openings and cause blockage of shielding gas
V groove or U groove
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
1/4 inch to 1/2 inch

2. How are GMAW guns rated?
Welding process that joins metals by heating them with an electric arc
Controls the rate of flow of a shielding gas to the gun nozzle
When the filler wire is in direct contract with the base metal
By there current carrying capacity

3. What happens when the electrode extension is increased?
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
The resistace to electrical current flow increases with it. Causing the electrode to heat
Motor driven generators - Transformer rectifiers - and Inverter designs

4. What type of power source is commonly used with a voltage sensing wire feeder?
SMAW - GTAW
3
Constant current (CC)
Motor driven generators - Transformer rectifiers - and Inverter designs

5. What is an advantage of pulsed arc transfer with GMAW?
Dry ice can form within the flow control openings and cause blockage of shielding gas
Puddle fluidity
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

6. What output on the welding machine is used to rate the duty cycle?
The Arc voltage
Controls the rate of flow of a shielding gas to the gun nozzle
Constant- speed wire feeders and Voltage- sennsing wire feeders
Minutes of elapsed time continually run (out of 10 minutes)

7. What current and polarity is generally used with GMAW?
Flux cored wires
DCEP (Direct Current Electrode Positive) Reverse Polarity
Higher 26 to 35 arc volts
Aluminum wire

8. What does a flowmeter do and what does it measure?
Controls the rate of flow of a shielding gas to the gun nozzle
Welding process that joins metals by heating them with an electric arc
15 feet (4.5 meters)
Wire feed speed - Voltage control

9. What processes are constant current (CC) power sources designed to be used with?
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
SMAW - GTAW
Duty cycle

10. Why is globular transfer generally avoided with GMAW?
...
Spatter problems and poor weld appearance
Minutes of elapsed time continually run (out of 10 minutes)
DCEP (Direct Current Electrode Positive) Reverse Polarity

11. What is another term for electrode holders for GMAW?
Insufficient current to melt the wire off cleanly
The resistace to electrical current flow increases with it. Causing the electrode to heat
Guns
Reducing the gas source pressure to a constant working pressure

12. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Flux cored wires
SMAW - GTAW
The resistace to electrical current flow increases with it. Causing the electrode to heat
Higher 26 to 35 arc volts

13. What controls amperage when using GMAW?
DCEP (Direct Current Electrode Positive) Reverse Polarity
(DCEP) Direct Current Electrode Positive or Reverse polarity
To prevent leakage - Carbon Dioxide (CO2)
Wire feed speed

14. What does voltage do in an electrical circuit?
Pressure - The rate of flow of a shielding gas
5.8 to 12.5 L/min
Voltage is the force that overcomes resistance to allow amperage flow
Duty cycle

15. What type of power source is used with a constant speed wire feeder?
If you dont know this check your phone
These terms are quite restrictive and often technically incorrect
Constant voltage (CV)
DCEP (Direct Current Electrode Positive) Reverse Polarity

16. List the basic equipment requirements for the GMAW process
Puddle fluidity
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Constant- speed wire feeders and Voltage- sennsing wire feeders
The negative side of a welding unit

17. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
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
(DCEP) Direct Current Electrode Positive or Reverse polarity
Higher 26 to 35 arc volts

18. What is the required arc voltage used for short circuit transfer?
Short- circuiting transfer - Globular transfer - Spray transfer
Dry ice can form within the flow control openings and cause blockage of shielding gas
5.8 to 12.5 L/min
12 to 22 arc volts

19. What is the main purpose of 'slope'?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Shielding the molten weld metal from atmospheric contamination
To limit the short circuiting current so that spatter is reduced
Wire feed speed - Voltage control

20. 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
Aluminum wire
5.8 to 12.5 L/min
Voltage is the force that overcomes resistance to allow amperage flow

21. In the GMAW process what does voltage control?
Spatter problems and poor weld appearance
Wire feed speed - Voltage control
Dry ice can form within the flow control openings and cause blockage of shielding gas
Puddle fluidity

22. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
Cause flaking - which can clog the liner and contact tube
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Minutes of elapsed time continually run (out of 10 minutes)
85%

23. When is the metal transferred with short circuit transfer?
The resistace to electrical current flow increases with it. Causing the electrode to heat
Guns
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
When the filler wire is in direct contract with the base metal

24. What are the 2 types of wire feeders available?
Welding Current - Filler wire diameter - arc length - type of shielding - position of 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
Constant- speed wire feeders and Voltage- sennsing wire feeders
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

25. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
20 to 200 times per second
Reducing the gas source pressure to a constant working pressure
Constant voltage (CV)
If you dont know this check your phone

26. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Generally not as accurate
Dry ice can form within the flow control openings and cause blockage of shielding gas
If you dont know this check your phone
These terms are quite restrictive and often technically incorrect

27. What power sources are used with the GMAW Process?
85%
Flux cored wires
The resistace to electrical current flow increases with it. Causing the electrode to heat
Motor driven generators - Transformer rectifiers - and Inverter designs

28. What 2 organizations designate specifications for GMAW wires?
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
AWS and CSA

29. What does inductance control?
By there current carrying capacity
The time rate of response for the current rise and fall
Wire feeds smoothly (yet will slip should a problem occur in the gun)
V groove or U groove

30. What is the maximum distance that hard wire can be successfully pushed?
(DCEP) Direct Current Electrode Positive or Reverse polarity
15 feet (4.5 meters)
Flux cored wires
To prevent leakage - Carbon Dioxide (CO2)

31. 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
National Electrical Manufactures Association
To prevent drawing of liquid CO2 (Carbon Dioxide)

32. What does the wire feeder control?
1/4 inch to 1/2 inch
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Speed of the feed motor and - starting / stopping electrode feed
Pressure vessels and the piping industry

33. What would be an indication that the drive roll pressure is adjusted correctly?
Wire feed speed - Voltage control
5.8 to 12.5 L/min
Pressure - The rate of flow of a shielding gas
Wire feeds smoothly (yet will slip should a problem occur in the gun)

34. Draw a typical volt amp curve for a machine that is designed for GMAW
Shielding the molten weld metal from atmospheric contamination
By there current carrying capacity
If you dont know this check your phone
When the filler wire is in direct contract with the base metal

35. What 2 controls are found on a GMAW set- up?
Constant- speed wire feeders and Voltage- sennsing wire feeders
Puddle fluidity
Wire feed speed - Voltage control
Higher 26 to 35 arc volts

36. List 3 wire drive systems and give a short description of each
National Electrical Manufactures Association
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
Higher 26 to 35 arc volts
Voltage is the force that overcomes resistance to allow amperage flow

37. What is the purpose of the shielding gas used in GMAW?
SMAW - GTAW
Shielding the molten weld metal from atmospheric contamination
To prevent leakage - Carbon Dioxide (CO2)
12 to 22 arc volts

38. What is a solenoid valve and what actuates it?
To prevent leakage - Carbon Dioxide (CO2)
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Puddle fluidity
Constant current (CC)

39. Give a brief description of the GMAW process
Pressure - The rate of flow of a shielding gas
The negative side of a welding unit
Welding process that joins metals by heating them with an electric arc
Motor driven generators - Transformer rectifiers - and Inverter designs

40. What controls the wire speed on a voltage sensing wire feeder?
Flux cored wires
Pressure vessels and the piping industry
The Arc voltage
Wire feed speed

41. Regulators control_____________ flowmeters SHOW____________.
If you dont know this check your phone
V groove or U groove
Minimum distortion due to low heat input
Pressure - The rate of flow of a shielding gas

42. List the three methods of metal transfer with GMAW
SMAW - GTAW
Minimum distortion due to low heat input
Short- circuiting transfer - Globular transfer - Spray transfer
The negative side of a welding unit

43. What wire are knurled drive rolls most commonly used on?
Duty cycle
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Flux cored wires
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

44. Give a description of 'pinch effect'
...
V groove or U groove
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Controls the rate of flow of a shielding gas to the gun nozzle

45. A pull type drive system is usually used on what type of material?
AWS and CSA
Generally not as accurate
Minutes of elapsed time continually run (out of 10 minutes)
Aluminum wire

46. 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
3
To prevent leakage - Carbon Dioxide (CO2)

47. Why is a line heater required when using GMAW?
The time rate of response for the current rise and fall
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
Cause flaking - which can clog the liner and contact tube

48. List the factors that determine the mode of metal transfer
Guns
Higher 26 to 35 arc volts
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Generally not as accurate

49. Why is a fiber washer required and what cylinder gas requires it?
12 to 22 arc volts
Speed of the feed motor and - starting / stopping electrode feed
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
To prevent leakage - Carbon Dioxide (CO2)

50. With straight polarity where is 2/3 of the arc energy?
Spatter problems and poor weld appearance
(DCEP) Direct Current Electrode Positive or Reverse polarity
The negative side of a welding unit
Gives arc voltage values to the control system of the feeder