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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. Why is the term GMAW preferred over MIG or MAG?
12 to 22 arc volts
Gas metal arc welding
These terms are quite restrictive and often technically incorrect
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

2. What is the required arc voltage used for short circuit transfer?
1/4 inch to 1/2 inch
Pressure vessels and the piping industry
12 to 22 arc volts
Gives arc voltage values to the control system of the feeder

3. What are the 2 types of wire feeders available?
Constant- speed wire feeders and Voltage- sennsing wire feeders
Controls the rate of flow of a shielding gas to the gun nozzle
Guns
12 to 22 arc volts

4. What is the recommended electrode stick- out for .035 solid wire?
Flux cored wires
Puddle fluidity
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

5. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
3
85%
Puddle fluidity
Reducing the gas source pressure to a constant working pressure

6. A pull type drive system is usually used on what type of material?
Higher 26 to 35 arc volts
Aluminum wire
15 feet (4.5 meters)
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

7. What is a solenoid valve and what actuates it?
Aluminum wire
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
(DCEP) Direct Current Electrode Positive or Reverse polarity
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

8. What 2 controls are found on a GMAW set- up?
Wire feed speed - Voltage control
Puddle fluidity
1/4 inch to 1/2 inch
85%

9. What is the purpose of a regulator and what does it indicate on its gauges?
85%
Constant- speed wire feeders and Voltage- sennsing wire feeders
DCEP (Direct Current Electrode Positive) Reverse Polarity
Reducing the gas source pressure to a constant working pressure

10. When is the metal transferred with short circuit transfer?
When the filler wire is in direct contract with the base metal
To prevent leakage - Carbon Dioxide (CO2)
Wire feed speed - Voltage control
V groove or U groove

11. What is a typical flow rate of CO2 for short circuit transfer?
If you dont know this check your phone
5.8 to 12.5 L/min
When the filler wire is in direct contract with the base metal
Dry ice can form within the flow control openings and cause blockage of shielding gas

12. Why must CO2 cylinders be used in the vertical position?
To prevent drawing of liquid CO2 (Carbon Dioxide)
Voltage is the force that overcomes resistance to allow amperage flow
Constant voltage (CV)
Higher 26 to 35 arc volts

13. What power sources are used with the GMAW Process?
Guns
Motor driven generators - Transformer rectifiers - and Inverter designs
Puddle fluidity
Flux cored wires

14. Give a brief description of the GMAW process
Welding process that joins metals by heating them with an electric arc
SMAW - GTAW
5.8 to 12.5 L/min
DCEP (Direct Current Electrode Positive) Reverse Polarity

15. List the factors that determine the mode of metal transfer
Puddle fluidity
To prevent drawing of liquid CO2 (Carbon Dioxide)
The Arc voltage
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

16. 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
Generally not as accurate
Pressure - The rate of flow of a shielding gas
Gives arc voltage values to the control system of the feeder

17. What does voltage do in an electrical circuit?
Guns
Cause flaking - which can clog the liner and contact tube
Generally not as accurate
Voltage is the force that overcomes resistance to allow amperage flow

18. List the three methods of metal transfer with GMAW
Constant voltage (CV)
National Electrical Manufactures Association
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Short- circuiting transfer - Globular transfer - Spray transfer

19. In the GMAW process what does voltage control?
Puddle fluidity
By there current carrying capacity
To limit the short circuiting current so that spatter is reduced
The time rate of response for the current rise and fall

20. Why is a fiber washer required and what cylinder gas requires it?
To prevent leakage - Carbon Dioxide (CO2)
If you dont know this check your phone
Minimum distortion due to low heat input
DCEP (Direct Current Electrode Positive) Reverse Polarity

21. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
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
(DCEP) Direct Current Electrode Positive or Reverse polarity
85%

22. Draw a typical volt amp curve for a machine that is designed for GMAW
Dry ice can form within the flow control openings and cause blockage of shielding gas
Constant- speed wire feeders and Voltage- sennsing wire feeders
Gas metal arc welding
If you dont know this check your phone

23. What wire are knurled drive rolls most commonly used on?
To prevent leakage - Carbon Dioxide (CO2)
Flux cored wires
Guns
Reducing the gas source pressure to a constant working pressure

24. What is the preferred drive roll design for solid wires?
20 to 200 times per second
V groove or U groove
AWS and CSA
Motor driven generators - Transformer rectifiers - and Inverter designs

25. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
(DCEP) Direct Current Electrode Positive or Reverse polarity
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
Generally not as accurate
12 to 22 arc volts

26. Give a description of 'pinch effect'
Shielding the molten weld metal from atmospheric contamination
By there current carrying capacity
To limit the short circuiting current so that spatter is reduced
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

27. What does a flowmeter do and what does it measure?
Gas metal arc welding
Controls the rate of flow of a shielding gas to the gun nozzle
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
Short- circuiting transfer - Globular transfer - Spray transfer

28. Regulators control_____________ flowmeters SHOW____________.
These terms are quite restrictive and often technically incorrect
Minutes of elapsed time continually run (out of 10 minutes)
The negative side of a welding unit
Pressure - The rate of flow of a shielding gas

29. Why is a line heater required when using GMAW?
...
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 Arc voltage
Dry ice can form within the flow control openings and cause blockage of shielding gas

30. What type of power source is commonly used with a voltage sensing wire feeder?
Pressure vessels and the piping industry
Constant current (CC)
Gas metal arc welding
Dry ice can form within the flow control openings and cause blockage of shielding gas

31. What controls the wire speed on a voltage sensing wire feeder?
The Arc voltage
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Minutes of elapsed time continually run (out of 10 minutes)
The resistace to electrical current flow increases with it. Causing the electrode to heat

32. What does the abbreviation NEMA stand for?
National Electrical Manufactures Association
To limit the short circuiting current so that spatter is reduced
(DCEP) Direct Current Electrode Positive or Reverse polarity
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

33. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
If you dont know this check your phone
Aluminum wire
SMAW - GTAW
To limit the short circuiting current so that spatter is reduced

34. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Gas metal arc welding
Cause flaking - which can clog the liner and contact tube
AWS and CSA
To prevent drawing of liquid CO2 (Carbon Dioxide)

35. What is another term for electrode holders for GMAW?
Motor driven generators - Transformer rectifiers - and Inverter designs
Wire feed speed
Minimum distortion due to low heat input
Guns

36. What is the key advantage of short circuiting transfer?
Wire feed speed - Voltage control
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Minimum distortion due to low heat input
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

37. How are GMAW guns rated?
By there current carrying capacity
Penetration and burn - off rate of the electrode
V groove or U groove
Short- circuiting transfer - Globular transfer - Spray transfer

38. What is an advantage of pulsed arc transfer with GMAW?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Constant- speed wire feeders and Voltage- sennsing wire feeders
Gives arc voltage values to the control system of the feeder
Wire feed speed

39. What type of power source is used with a constant speed wire feeder?
V groove or U groove
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
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

40. What 2 organizations designate specifications for GMAW wires?
To prevent leakage - Carbon Dioxide (CO2)
Constant voltage (CV)
AWS and CSA
Motor driven generators - Transformer rectifiers - and Inverter designs

41. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Generally not as accurate
Insufficient current to melt the wire off cleanly
The resistace to electrical current flow increases with it. Causing the electrode to heat
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

42. What does the wire feeder control?
Puddle fluidity
Speed of the feed motor and - starting / stopping electrode feed
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

43. What output on the welding machine is used to rate the duty cycle?
Welding process that joins metals by heating them with an electric arc
Shielding the molten weld metal from atmospheric contamination
Minutes of elapsed time continually run (out of 10 minutes)
DCEP (Direct Current Electrode Positive) Reverse Polarity

44. In the GMAW process what does amperage control?
The negative side of a welding unit
AWS and CSA
Cause flaking - which can clog the liner and contact tube
Penetration and burn - off rate of the electrode

45. What processes are constant current (CC) power sources designed to be used with?
To limit the short circuiting current so that spatter is reduced
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
SMAW - GTAW

46. What does the term GMAW identify?
Welding process that joins metals by heating them with an electric arc
Gas metal arc welding
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

47. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Constant- speed wire feeders and Voltage- sennsing wire feeders
Higher 26 to 35 arc volts
To prevent drawing of liquid CO2 (Carbon Dioxide)
If you dont know this check your phone

48. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Penetration and burn - off rate of the electrode
Duty cycle
Shielding the molten weld metal from atmospheric contamination
The negative side of a welding unit

49. What would be an indication that the drive roll pressure is adjusted correctly?
1/4 inch to 1/2 inch
Wire feeds smoothly (yet will slip should a problem occur in the gun)
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
Dry ice can form within the flow control openings and cause blockage of shielding gas

50. What does inductance control?
The time rate of response for the current rise and fall
Motor driven generators - Transformer rectifiers - and Inverter designs
Wire feed speed
...