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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. What is a solenoid valve and what actuates it?
The negative side of a welding unit
The time rate of response for the current rise and fall
Wire feed speed
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

2. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
3
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Wire feeds smoothly (yet will slip should a problem occur in the gun)
Guns

3. What would be an indication that the drive roll pressure is adjusted correctly?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Guns
Motor driven generators - Transformer rectifiers - and Inverter designs
Generally not as accurate

4. When is the metal transferred with short circuit transfer?
AWS and CSA
Constant voltage (CV)
The negative side of a welding unit
When the filler wire is in direct contract with the base metal

5. Why is a line heater required when using GMAW?
Voltage is the force that overcomes resistance to allow amperage flow
12 to 22 arc volts
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

6. What current and polarity is generally used with GMAW?
DCEP (Direct Current Electrode Positive) Reverse Polarity
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Duty cycle
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

7. List the factors that determine the mode of metal transfer
Reducing the gas source pressure to a constant working pressure
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
These terms are quite restrictive and often technically incorrect
15 feet (4.5 meters)

8. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Motor driven generators - Transformer rectifiers - and Inverter designs
Gives arc voltage values to the control system of the feeder
The resistace to electrical current flow increases with it. Causing the electrode to heat

9. In the GMAW process what does voltage control?
Voltage is the force that overcomes resistance to allow amperage flow
(DCEP) Direct Current Electrode Positive or Reverse polarity
Puddle fluidity
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

10. What output on the welding machine is used to rate the duty cycle?
Minutes of elapsed time continually run (out of 10 minutes)
Voltage is the force that overcomes resistance to allow amperage flow
Aluminum wire
Reducing the gas source pressure to a constant working pressure

11. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
The resistace to electrical current flow increases with it. Causing the electrode to heat
Motor driven generators - Transformer rectifiers - and Inverter designs
Controls the rate of flow of a shielding gas to the gun nozzle
(DCEP) Direct Current Electrode Positive or Reverse polarity

12. What is the recommended electrode stick- out for .035 solid wire?
Minutes of elapsed time continually run (out of 10 minutes)
1/4 inch to 1/2 inch
12 to 22 arc volts
Wire feeds smoothly (yet will slip should a problem occur in the gun)

13. List 3 wire drive systems and give a short description of each
Flux cored 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
Gives arc voltage values to the control system of the feeder
Wire feed speed

14. What does the wire feeder control?
When the filler wire is in direct contract with the base metal
Speed of the feed motor and - starting / stopping electrode feed
Penetration and burn - off rate of the electrode
Wire feed speed

15. Why is the term GMAW preferred over MIG or MAG?
These terms are quite restrictive and often technically incorrect
1/4 inch to 1/2 inch
SMAW - GTAW
15 feet (4.5 meters)

16. What does a flowmeter do and what does it measure?
The negative side of a welding unit
Controls the rate of flow of a shielding gas to the gun nozzle
20 to 200 times per second
...

17. Give a description of 'pinch effect'
Insufficient current to melt the wire off cleanly
3
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Penetration and burn - off rate of the electrode

18. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
(DCEP) Direct Current Electrode Positive or Reverse polarity
85%
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
20 to 200 times per second

19. Why is a fiber washer required and what cylinder gas requires it?
Gas metal arc welding
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
To prevent leakage - Carbon Dioxide (CO2)
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

20. With straight polarity where is 2/3 of the arc energy?
Motor driven generators - Transformer rectifiers - and Inverter designs
Wire feeds smoothly (yet will slip should a problem occur in the gun)
20 to 200 times per second
The negative side of a welding unit

21. Draw a typical volt amp curve for a machine that is designed for GMAW
Shielding the molten weld metal from atmospheric contamination
If you dont know this check your phone
Minimum distortion due to low heat input
Pressure - The rate of flow of a shielding gas

22. What 2 controls are found on a GMAW set- up?
15 feet (4.5 meters)
DCEP (Direct Current Electrode Positive) Reverse Polarity
Wire feed speed - Voltage control
Shielding the molten weld metal from atmospheric contamination

23. What is an advantage of pulsed arc transfer with GMAW?
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
To limit the short circuiting current so that spatter is reduced
Constant- speed wire feeders and Voltage- sennsing wire feeders

24. What processes are constant current (CC) power sources designed to be used with?
SMAW - GTAW
To prevent leakage - Carbon Dioxide (CO2)
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Minimum distortion due to low heat input

25. What type of power source is commonly used with a voltage sensing wire feeder?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Constant current (CC)
Gives arc voltage values to the control system of the feeder
Speed of the feed motor and - starting / stopping electrode feed

26. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
The resistace to electrical current flow increases with it. Causing the electrode to heat
Cause flaking - which can clog the liner and contact tube
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Penetration and burn - off rate of the electrode

27. What does voltage do in an electrical circuit?
12 to 22 arc volts
Constant- speed wire feeders and Voltage- sennsing wire feeders
Voltage is the force that overcomes resistance to allow amperage flow
SMAW - GTAW

28. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Duty cycle
Spatter problems and poor weld appearance
Guns
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29. What is the main purpose of 'slope'?
Insufficient current to melt the wire off cleanly
Cause flaking - which can clog the liner and contact tube
To limit the short circuiting current so that spatter is reduced
To prevent drawing of liquid CO2 (Carbon Dioxide)

30. What effect does increasing and decreasing the inductance have on the weld?
Welding process that joins metals by heating them with an electric arc
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
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.
5.8 to 12.5 L/min
Welding process that joins metals by heating them with an electric arc
Wire feed speed
3

32. What does the abbreviation NEMA stand for?
85%
Minutes of elapsed time continually run (out of 10 minutes)
5.8 to 12.5 L/min
National Electrical Manufactures Association

33. What is another term for electrode holders for GMAW?
Reducing the gas source pressure to a constant working pressure
Wire feed speed - Voltage control
The Arc voltage
Guns

34. What does the term GMAW identify?
Gas metal arc welding
To prevent drawing of liquid CO2 (Carbon Dioxide)
When the filler wire is in direct contract with the base metal
These terms are quite restrictive and often technically incorrect

35. In the GMAW process what does amperage control?
Penetration and burn - off rate of the electrode
Motor driven generators - Transformer rectifiers - and Inverter designs
Voltage is the force that overcomes resistance to allow amperage flow
Cause flaking - which can clog the liner and contact tube

36. Why must CO2 cylinders be used in the vertical position?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
DCEP (Direct Current Electrode Positive) Reverse Polarity
These terms are quite restrictive and often technically incorrect
To prevent drawing of liquid CO2 (Carbon Dioxide)

37. Give a brief description of the GMAW process
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
Welding process that joins metals by heating them with an electric arc
...
Constant- speed wire feeders and Voltage- sennsing wire feeders

38. A pull type drive system is usually used on what type of material?
85%
Flux cored wires
Aluminum wire
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

39. What controls amperage when using GMAW?
Reducing the gas source pressure to a constant working pressure
Wire feed speed
To limit the short circuiting current so that spatter is reduced
Motor driven generators - Transformer rectifiers - and Inverter designs

40. What type of power source is used with a constant speed wire feeder?
Constant voltage (CV)
Generally not as accurate
SMAW - GTAW
Speed of the feed motor and - starting / stopping electrode feed

41. What is the effect of too much slope?
AWS and CSA
The Arc voltage
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Insufficient current to melt the wire off cleanly

42. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Generally not as accurate
Constant voltage (CV)
Short- circuiting transfer - Globular transfer - Spray transfer
Constant- speed wire feeders and Voltage- sennsing wire feeders

43. What is the maximum distance that hard wire can be successfully pushed?
To limit the short circuiting current so that spatter is reduced
The resistace to electrical current flow increases with it. Causing the electrode to heat
15 feet (4.5 meters)
If you dont know this check your phone

44. What does inductance control?
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
Constant voltage (CV)
20 to 200 times per second

45. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
Duty cycle
...
Guns
Minimum distortion due to low heat input

46. List several industries that would use GMAW
Pressure vessels and the piping industry
Wire feed speed - Voltage control
To prevent leakage - Carbon Dioxide (CO2)
DCEP (Direct Current Electrode Positive) Reverse Polarity

47. Why is globular transfer generally avoided with GMAW?
Spatter problems and poor weld appearance
The time rate of response for the current rise and fall
Penetration and burn - off rate of the electrode
Wire feeds smoothly (yet will slip should a problem occur in the gun)

48. How are GMAW guns rated?
National Electrical Manufactures Association
Dry ice can form within the flow control openings and cause blockage of shielding gas
By there current carrying capacity
Penetration and burn - off rate of the electrode

49. What is a typical flow rate of CO2 for short circuit transfer?
Constant current (CC)
Constant voltage (CV)
5.8 to 12.5 L/min
By there current carrying capacity

50. What is the key advantage of short circuiting transfer?
Minimum distortion due to low heat input
Shielding the molten weld metal from atmospheric contamination
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Minutes of elapsed time continually run (out of 10 minutes)