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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. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Duty cycle
Cause flaking - which can clog the liner and contact tube
Puddle fluidity
The resistace to electrical current flow increases with it. Causing the electrode to heat

2. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
To prevent drawing of liquid CO2 (Carbon Dioxide)
Higher 26 to 35 arc volts
V groove or U groove
Controls the rate of flow of a shielding gas to the gun nozzle

3. What is the maximum distance that hard wire can be successfully pushed?
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Penetration and burn - off rate of the electrode
15 feet (4.5 meters)
Shielding the molten weld metal from atmospheric contamination

4. What 2 organizations designate specifications for GMAW wires?
Shielding the molten weld metal from atmospheric contamination
85%
These terms are quite restrictive and often technically incorrect
AWS and CSA

5. How are GMAW guns rated?
Wire feed speed - Voltage control
Constant current (CC)
By there current carrying capacity
Guns

6. What does the term GMAW identify?
Gas metal arc welding
Higher 26 to 35 arc volts
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

7. What happens when the electrode extension is increased?
These terms are quite restrictive and often technically incorrect
Duty cycle
SMAW - GTAW
The resistace to electrical current flow increases with it. Causing the electrode to heat

8. What is another term for electrode holders for GMAW?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Guns
Wire feed speed

9. List 3 forms compressed gases may be supplied for welding
These terms are quite restrictive and often technically incorrect
Minimum distortion due to low heat input
Speed of the feed motor and - starting / stopping electrode feed
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

10. Why is the term GMAW preferred over MIG or MAG?
Reducing the gas source pressure to a constant working pressure
The resistace to electrical current flow increases with it. Causing the electrode to heat
These terms are quite restrictive and often technically incorrect
Dry ice can form within the flow control openings and cause blockage of shielding gas

11. Why is a fiber washer required and what cylinder gas requires it?
Pressure - The rate of flow of a shielding gas
The resistace to electrical current flow increases with it. Causing the electrode to heat
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To prevent leakage - Carbon Dioxide (CO2)

12. List the factors that determine the mode of metal transfer
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Wire feed speed - Voltage control
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Cause flaking - which can clog the liner and contact tube

13. What controls amperage when using GMAW?
The Arc voltage
Wire feed speed
V groove or U groove
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14. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Generally not as accurate
Aluminum wire
The time rate of response for the current rise and fall
Shielding the molten weld metal from atmospheric contamination

15. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
20 to 200 times per second
Pressure vessels and the piping industry
Cause flaking - which can clog the liner and contact tube
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16. What type of power source is commonly used with a voltage sensing wire feeder?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Constant- speed wire feeders and Voltage- sennsing wire feeders
Constant current (CC)
Insufficient current to melt the wire off cleanly

17. What power sources are used with the GMAW Process?
Motor driven generators - Transformer rectifiers - and Inverter designs
Minimum distortion due to low heat input
Shielding the molten weld metal from atmospheric contamination
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

18. List the basic equipment requirements for the GMAW process
Wire feed speed
Wire feed speed - Voltage control
20 to 200 times per second
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

19. What type of power source is used with a constant speed wire feeder?
Pressure - The rate of flow of a shielding gas
Constant voltage (CV)
The time rate of response for the current rise and fall
SMAW - GTAW

20. When is the metal transferred with short circuit transfer?
SMAW - GTAW
When the filler wire is in direct contract with the base metal
DCEP (Direct Current Electrode Positive) Reverse Polarity
Dry ice can form within the flow control openings and cause blockage of shielding gas

21. What processes are constant current (CC) power sources designed to be used with?
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Insufficient current to melt the wire off cleanly
SMAW - GTAW
Reducing the gas source pressure to a constant working pressure

22. What does a flowmeter do and what does it measure?
Controls the rate of flow of a shielding gas to the gun nozzle
1/4 inch to 1/2 inch
Reducing the gas source pressure to a constant working pressure
Motor driven generators - Transformer rectifiers - and Inverter designs

23. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
Flux cored wires
Constant- speed wire feeders and Voltage- sennsing wire feeders
(DCEP) Direct Current Electrode Positive or Reverse polarity
These terms are quite restrictive and often technically incorrect

24. Why is a line heater required when using GMAW?
15 feet (4.5 meters)
DCEP (Direct Current Electrode Positive) Reverse Polarity
To prevent leakage - Carbon Dioxide (CO2)
Dry ice can form within the flow control openings and cause blockage of shielding gas

25. What is the required arc voltage used for short circuit transfer?
Reducing the gas source pressure to a constant working pressure
Gives arc voltage values to the control system of the feeder
12 to 22 arc volts
Guns

26. What does inductance control?
20 to 200 times per second
Speed of the feed motor and - starting / stopping electrode feed
Minutes of elapsed time continually run (out of 10 minutes)
The time rate of response for the current rise and fall

27. What would be an indication that the drive roll pressure is adjusted correctly?
Shielding the molten weld metal from atmospheric contamination
3
Wire feeds smoothly (yet will slip should a problem occur in the gun)
The Arc voltage

28. What 2 controls are found on a GMAW set- up?
Puddle fluidity
Constant current (CC)
These terms are quite restrictive and often technically incorrect
Wire feed speed - Voltage control

29. Why is globular transfer generally avoided with GMAW?
Aluminum wire
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Spatter problems and poor weld appearance
Pressure vessels and the piping industry

30. How many times per second does short circuiting take place?
20 to 200 times per second
The resistace to electrical current flow increases with it. Causing the electrode to heat
Welding process that joins metals by heating them with an electric arc
Minutes of elapsed time continually run (out of 10 minutes)

31. What controls the wire speed on a voltage sensing wire feeder?
5.8 to 12.5 L/min
The Arc voltage
Short- circuiting transfer - Globular transfer - Spray transfer
Voltage is the force that overcomes resistance to allow amperage flow

32. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
Short- circuiting transfer - Globular transfer - Spray transfer
Motor driven generators - Transformer rectifiers - and Inverter designs
...
Constant- speed wire feeders and Voltage- sennsing wire feeders

33. What current and polarity is generally used with GMAW?
...
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DCEP (Direct Current Electrode Positive) Reverse Polarity
Motor driven generators - Transformer rectifiers - and Inverter designs

34. What does voltage do in an electrical circuit?
Puddle fluidity
Voltage is the force that overcomes resistance to allow amperage flow
Short- circuiting transfer - Globular transfer - Spray transfer
Cause flaking - which can clog the liner and contact tube

35. 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
Dry ice can form within the flow control openings and cause blockage of shielding gas
5.8 to 12.5 L/min
Duty cycle

36. What is the key advantage of short circuiting transfer?
Wire feed speed - Voltage control
Speed of the feed motor and - starting / stopping electrode feed
Minimum distortion due to low heat input
These terms are quite restrictive and often technically incorrect

37. What does the wire feeder control?
Wire feed speed
Speed of the feed motor and - starting / stopping electrode feed
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

38. Give a description of 'pinch effect'
1/4 inch to 1/2 inch
The Arc voltage
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
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. Why must CO2 cylinders be used in the vertical position?
When the filler wire is in direct contract with the base metal
The Arc voltage
To prevent drawing of liquid CO2 (Carbon Dioxide)
Penetration and burn - off rate of the electrode

40. Give a brief description of the GMAW process
Welding process that joins metals by heating them with an electric arc
Shielding the molten weld metal from atmospheric contamination
The Arc voltage
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

41. What is the main purpose of 'slope'?
To limit the short circuiting current so that spatter is reduced
3
Gives arc voltage values to the control system of the feeder
Welding process that joins metals by heating them with an electric arc

42. What is a typical flow rate of CO2 for short circuit transfer?
5.8 to 12.5 L/min
Penetration and burn - off rate of the electrode
Puddle fluidity
Constant- speed wire feeders and Voltage- sennsing wire feeders

43. With straight polarity where is 2/3 of the arc energy?
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Motor driven generators - Transformer rectifiers - and Inverter designs
Shielding the molten weld metal from atmospheric contamination
The negative side of a welding unit

44. What wire are knurled drive rolls most commonly used on?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
By there current carrying capacity
Voltage is the force that overcomes resistance to allow amperage flow
Flux cored wires

45. What is the purpose of a regulator and what does it indicate on its gauges?
15 feet (4.5 meters)
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
Reducing the gas source pressure to a constant working pressure

46. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
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
Speed of the feed motor and - starting / stopping electrode feed
National Electrical Manufactures Association
85%

47. What is the purpose of the shielding gas used in GMAW?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
20 to 200 times per second
Spatter problems and poor weld appearance
Shielding the molten weld metal from atmospheric contamination

48. What output on the welding machine is used to rate the duty cycle?
Spatter problems and poor weld appearance
Dry ice can form within the flow control openings and cause blockage of shielding gas
5.8 to 12.5 L/min
Minutes of elapsed time continually run (out of 10 minutes)

49. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
AWS and CSA
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
To prevent drawing of liquid CO2 (Carbon Dioxide)
3

50. Draw a typical volt amp curve for a machine that is designed for GMAW
Spatter problems and poor weld appearance
Generally not as accurate
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Pressure vessels and the piping industry