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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 machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
3
Gas metal arc welding

2. What wire are knurled drive rolls most commonly used on?
5.8 to 12.5 L/min
To prevent leakage - Carbon Dioxide (CO2)
Insufficient current to melt the wire off cleanly
Flux cored wires

3. What type of power source is commonly used with a voltage sensing wire feeder?
5.8 to 12.5 L/min
The negative side of a welding unit
Minimum distortion due to low heat input
Constant current (CC)

4. What would be an indication that the drive roll pressure is adjusted correctly?
3
Insufficient current to melt the wire off cleanly
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Wire feed speed - Voltage control

5. Why is a line heater required when using GMAW?
Dry ice can form within the flow control openings and cause blockage of shielding gas
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
(DCEP) Direct Current Electrode Positive or Reverse polarity
AWS and CSA

6. List 3 forms compressed gases may be supplied for welding
Wire feed speed
Guns
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
When the filler wire is in direct contract with the base metal

7. A pull type drive system is usually used on what type of material?
Gas metal arc welding
Aluminum wire
15 feet (4.5 meters)
To prevent leakage - Carbon Dioxide (CO2)

8. Why is the term GMAW preferred over MIG or MAG?
Speed of the feed motor and - starting / stopping electrode feed
Guns
Constant- speed wire feeders and Voltage- sennsing wire feeders
These terms are quite restrictive and often technically incorrect

9. What current and polarity is generally used with GMAW?
Constant current (CC)
5.8 to 12.5 L/min
20 to 200 times per second
DCEP (Direct Current Electrode Positive) Reverse Polarity

10. What output on the welding machine is used to rate the duty cycle?
If you dont know this check your phone
...
Minutes of elapsed time continually run (out of 10 minutes)
By there current carrying capacity

11. What is the purpose of a regulator and what does it indicate on its gauges?
Reducing the gas source pressure to a constant working pressure
Minutes of elapsed time continually run (out of 10 minutes)
Shielding the molten weld metal from atmospheric contamination
To prevent leakage - Carbon Dioxide (CO2)

12. What is a solenoid valve and what actuates it?
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) Reverse Polarity
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
To prevent leakage - Carbon Dioxide (CO2)

13. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
AWS and CSA
By there current carrying capacity
If you dont know this check your phone
Wire feeds smoothly (yet will slip should a problem occur in the gun)

14. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Welding process that joins metals by heating them with an electric arc
SMAW - GTAW
Gives arc voltage values to the control system of the feeder
Generally not as accurate

15. What is an advantage of pulsed arc transfer with GMAW?
20 to 200 times per second
Guns
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Wire feed speed

16. What does the term GMAW identify?
The time rate of response for the current rise and fall
(DCEP) Direct Current Electrode Positive or Reverse polarity
Gas metal arc welding
Spatter problems and poor weld appearance

17. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
Speed of the feed motor and - starting / stopping electrode feed
...
The Arc voltage
To prevent leakage - Carbon Dioxide (CO2)

18. What does voltage do in an electrical circuit?
To prevent leakage - Carbon Dioxide (CO2)
Voltage is the force that overcomes resistance to allow amperage flow
Wire feed speed
Insufficient current to melt the wire off cleanly

19. What is the effect of too much slope?
Insufficient current to melt the wire off cleanly
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Minutes of elapsed time continually run (out of 10 minutes)
V groove or U groove

20. What power sources are used with the GMAW Process?
Dry ice can form within the flow control openings and cause blockage of shielding gas
5.8 to 12.5 L/min
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Motor driven generators - Transformer rectifiers - and Inverter designs

21. Draw a typical volt amp curve for a machine that is designed for GMAW
If you dont know this check your phone
Pressure - The rate of flow of a shielding gas
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
1/4 inch to 1/2 inch

22. What does the wire feeder control?
Pressure - The rate of flow of a shielding gas
Speed of the feed motor and - starting / stopping electrode feed
Welding process that joins metals by heating them with an electric arc
If you dont know this check your phone

23. What controls the wire speed on a voltage sensing wire feeder?
AWS and CSA
The negative side of a welding unit
The Arc voltage
To prevent leakage - Carbon Dioxide (CO2)

24. When is the metal transferred with short circuit transfer?
Minutes of elapsed time continually run (out of 10 minutes)
20 to 200 times per second
Penetration and burn - off rate of the electrode
When the filler wire is in direct contract with the base metal

25. List the basic equipment requirements for the GMAW process
Gives arc voltage values to the control system of the feeder
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
AWS and CSA
1/4 inch to 1/2 inch

26. A 10 minute cycle of welding time vs cooling time a given machine can handle.
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
Pressure vessels and the piping industry
Duty cycle

27. What is the recommended electrode stick- out for .035 solid wire?
12 to 22 arc volts
1/4 inch to 1/2 inch
Minimum distortion due to low heat input
National Electrical Manufactures Association

28. What 2 organizations designate specifications for GMAW wires?
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
Minutes of elapsed time continually run (out of 10 minutes)
AWS and CSA

29. Why must CO2 cylinders be used in the vertical position?
Constant voltage (CV)
Wire feeds smoothly (yet will slip should a problem occur in the gun)
To prevent drawing of liquid CO2 (Carbon Dioxide)
To limit the short circuiting current so that spatter is reduced

30. What does a flowmeter do and what does it measure?
To limit the short circuiting current so that spatter is reduced
Gas metal arc welding
Controls the rate of flow of a shielding gas to the gun nozzle
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

31. What is the main purpose of 'slope'?
To limit the short circuiting current so that spatter is reduced
Flux cored wires
Dry ice can form within the flow control openings and cause blockage of shielding gas
Controls the rate of flow of a shielding gas to the gun nozzle

32. Regulators control_____________ flowmeters SHOW____________.
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
To prevent drawing of liquid CO2 (Carbon Dioxide)
20 to 200 times per second
Pressure - The rate of flow of a shielding gas

33. What is the key advantage of short circuiting transfer?
The resistace to electrical current flow increases with it. Causing the electrode to heat
Minimum distortion due to low heat input
Duty cycle
Constant voltage (CV)

34. What processes are constant current (CC) power sources designed to be used with?
Speed of the feed motor and - starting / stopping electrode feed
Constant- speed wire feeders and Voltage- sennsing wire feeders
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
SMAW - GTAW

35. With straight polarity where is 2/3 of the arc energy?
V groove or U groove
The negative side of a welding unit
Puddle fluidity
Insufficient current to melt the wire off cleanly

36. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Generally not as accurate
Gives arc voltage values to the control system of the feeder
1/4 inch to 1/2 inch
Penetration and burn - off rate of the electrode

37. What does the abbreviation NEMA stand for?
The time rate of response for the current rise and fall
Penetration and burn - off rate of the electrode
Speed of the feed motor and - starting / stopping electrode feed
National Electrical Manufactures Association

38. What is the purpose of the shielding gas used in GMAW?
Shielding the molten weld metal from atmospheric contamination
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
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
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

39. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
15 feet (4.5 meters)
(DCEP) Direct Current Electrode Positive or Reverse polarity
Aluminum wire
National Electrical Manufactures Association

40. What is another term for electrode holders for GMAW?
3
Voltage is the force that overcomes resistance to allow amperage flow
15 feet (4.5 meters)
Guns

41. What are the 2 types of wire feeders available?
Constant voltage (CV)
12 to 22 arc volts
Constant- speed wire feeders and Voltage- sennsing wire feeders
1/4 inch to 1/2 inch

42. 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
Motor driven generators - Transformer rectifiers - and Inverter designs
Wire feed speed
Pressure - The rate of flow of a shielding gas

43. List the factors that determine the mode of metal transfer
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Insufficient current to melt the wire off cleanly
(DCEP) Direct Current Electrode Positive or Reverse polarity
Pressure - The rate of flow of a shielding gas

44. How are GMAW guns rated?
Constant voltage (CV)
3
By there current carrying capacity
DCEP (Direct Current Electrode Positive) Reverse Polarity

45. What 2 controls are found on a GMAW set- up?
SMAW - GTAW
V groove or U groove
Wire feed speed - Voltage control
Shielding the molten weld metal from atmospheric contamination

46. What does inductance control?
The negative side of a welding unit
To limit the short circuiting current so that spatter is reduced
The Arc voltage
The time rate of response for the current rise and fall

47. List several industries that would use GMAW
Controls the rate of flow of a shielding gas to the gun nozzle
V groove or U groove
Reducing the gas source pressure to a constant working pressure
Pressure vessels and the piping industry

48. What controls amperage when using GMAW?
Gives arc voltage values to the control system of the feeder
Minimum distortion due to low heat input
Wire feed speed
12 to 22 arc volts

49. Why is a fiber washer required and what cylinder gas requires it?
Guns
To prevent leakage - Carbon Dioxide (CO2)
The negative side of a welding unit
V groove or U groove

50. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
AWS and CSA
Spatter problems and poor weld appearance
Higher 26 to 35 arc volts
Insufficient current to melt the wire off cleanly