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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. Give a brief description of the GMAW process
Welding process that joins metals by heating them with an electric arc
When the filler wire is in direct contract with the base metal
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

2. Regulators control_____________ flowmeters SHOW____________.
Gives arc voltage values to the control system of the feeder
Insufficient current to melt the wire off cleanly
Pressure - The rate of flow of a shielding gas
Flux cored wires

3. With straight polarity where is 2/3 of the arc energy?
These terms are quite restrictive and often technically incorrect
...
The negative side of a welding unit
Speed of the feed motor and - starting / stopping electrode feed

4. What happens when the electrode extension is increased?
Wire feed speed
The Arc voltage
The resistace to electrical current flow increases with it. Causing the electrode to heat
National Electrical Manufactures Association

5. 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
To prevent leakage - Carbon Dioxide (CO2)
When the filler wire is in direct contract with the base metal
Constant voltage (CV)

6. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Higher 26 to 35 arc volts
Welding process that joins metals by heating them with an electric arc
To prevent leakage - Carbon Dioxide (CO2)
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

7. What does the abbreviation NEMA stand for?
DCEP (Direct Current Electrode Positive) Reverse Polarity
National Electrical Manufactures Association
Constant current (CC)
To prevent leakage - Carbon Dioxide (CO2)

8. What is the required arc voltage used for short circuit transfer?
12 to 22 arc volts
Spatter problems and poor weld appearance
When the filler wire is in direct contract with the base metal
By there current carrying capacity

9. Why is the term GMAW preferred over MIG or MAG?
SMAW - GTAW
Constant- speed wire feeders and Voltage- sennsing wire feeders
3
These terms are quite restrictive and often technically incorrect

10. When is the metal transferred with short circuit transfer?
To limit the short circuiting current so that spatter is reduced
AWS and CSA
Wire feed speed
When the filler wire is in direct contract with the base metal

11. What 2 organizations designate specifications for GMAW wires?
SMAW - GTAW
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Motor driven generators - Transformer rectifiers - and Inverter designs
AWS and CSA

12. What power sources are used with the GMAW Process?
Motor driven generators - Transformer rectifiers - and Inverter designs
12 to 22 arc volts
Generally not as accurate
Speed of the feed motor and - starting / stopping electrode feed

13. Why is globular transfer generally avoided with GMAW?
V groove or U groove
Spatter problems and poor weld appearance
The time rate of response for the current rise and fall
Wire feeds smoothly (yet will slip should a problem occur in the gun)

14. Why is a line heater required when using GMAW?
Dry ice can form within the flow control openings and cause blockage of shielding gas
The time rate of response for the current rise and fall
Constant current (CC)
To prevent drawing of liquid CO2 (Carbon Dioxide)

15. What does the term GMAW identify?
Gas metal arc welding
To prevent drawing of liquid CO2 (Carbon Dioxide)
Penetration and burn - off rate of the electrode
Cause flaking - which can clog the liner and contact tube

16. What is the recommended electrode stick- out for .035 solid wire?
When the filler wire is in direct contract with the base metal
Controls the rate of flow of a shielding gas to the gun nozzle
Shielding the molten weld metal from atmospheric contamination
1/4 inch to 1/2 inch

17. What effect does increasing and decreasing the inductance have on the weld?
The Arc voltage
Controls the rate of flow of a shielding gas to the gun nozzle
Wire feed speed - Voltage control
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

18. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
12 to 22 arc volts
3
Penetration and burn - off rate of the electrode
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

19. What processes are constant current (CC) power sources designed to be used with?
Duty cycle
Cause flaking - which can clog the liner and contact tube
The Arc voltage
SMAW - GTAW

20. List 3 wire drive systems and give a short description of each
Aluminum wire
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
Wire feed speed - Voltage control

21. What is another term for electrode holders for GMAW?
If you dont know this check your phone
Guns
Speed of the feed motor and - starting / stopping electrode feed
Minimum distortion due to low heat input

22. Draw a typical volt amp curve for a machine that is designed for GMAW
Generally not as accurate
DCEP (Direct Current Electrode Positive) Reverse Polarity
Constant current (CC)
If you dont know this check your phone

23. What wire are knurled drive rolls most commonly used on?
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
Flux cored wires
...

24. What would be an indication that the drive roll pressure is adjusted correctly?
To prevent drawing of liquid CO2 (Carbon Dioxide)
DCEP (Direct Current Electrode Positive) Reverse Polarity
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Shielding the molten weld metal from atmospheric contamination

25. What 2 controls are found on a GMAW set- up?
Constant current (CC)
The Arc voltage
Wire feed speed - Voltage control
Guns

26. 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
AWS and CSA
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
To prevent leakage - Carbon Dioxide (CO2)

27. 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
Speed of the feed motor and - starting / stopping electrode feed
Motor driven generators - Transformer rectifiers - and Inverter designs
DCEP (Direct Current Electrode Positive) Reverse Polarity

28. List the basic equipment requirements for the GMAW process
Wire feed speed - Voltage control
Welding process that joins metals by heating them with an electric arc
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

29. How many times per second does short circuiting take place?
The negative side of a welding unit
(DCEP) Direct Current Electrode Positive or Reverse polarity
20 to 200 times per second
Penetration and burn - off rate of the electrode

30. What is the maximum distance that hard wire can be successfully pushed?
Puddle fluidity
Gives arc voltage values to the control system of the feeder
Penetration and burn - off rate of the electrode
15 feet (4.5 meters)

31. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Duty cycle
The time rate of response for the current rise and fall
DCEP (Direct Current Electrode Positive) Reverse Polarity
Pressure vessels and the piping industry

32. Why must CO2 cylinders be used in the vertical position?
To prevent drawing of liquid CO2 (Carbon Dioxide)
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
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Spatter problems and poor weld appearance

33. What current and polarity is generally used with GMAW?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Dry ice can form within the flow control openings and cause blockage of shielding gas
Reducing the gas source pressure to a constant working pressure
Speed of the feed motor and - starting / stopping electrode feed

34. What output on the welding machine is used to rate the duty cycle?
Minutes of elapsed time continually run (out of 10 minutes)
Duty cycle
National Electrical Manufactures Association
Aluminum wire

35. What type of power source is used with a constant speed wire feeder?
Constant voltage (CV)
Aluminum wire
Short- circuiting transfer - Globular transfer - Spray transfer
Shielding the molten weld metal from atmospheric contamination

36. List several industries that would use GMAW
Pressure vessels and the piping industry
Minimum distortion due to low heat input
Wire feed speed
The time rate of response for the current rise and fall

37. What does inductance control?
Reducing the gas source pressure to a constant working pressure
The time rate of response for the current rise and fall
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Constant current (CC)

38. What is the effect of too much slope?
20 to 200 times per second
Insufficient current to melt the wire off cleanly
Cause flaking - which can clog the liner and contact tube
Minimum distortion due to low heat input

39. List the factors that determine the mode of metal transfer
Insufficient current to melt the wire off cleanly
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Minimum distortion due to low heat input
The Arc voltage

40. A pull type drive system is usually used on what type of material?
Aluminum wire
(DCEP) Direct Current Electrode Positive or Reverse polarity
Cause flaking - which can clog the liner and contact tube
V groove or U groove

41. What controls the wire speed on a voltage sensing wire feeder?
Minimum distortion due to low heat input
The Arc voltage
Wire feed speed - Voltage control
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

42. List 3 forms compressed gases may be supplied for welding
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Spatter problems and poor weld appearance
12 to 22 arc volts
Duty cycle

43. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
To prevent drawing of liquid CO2 (Carbon Dioxide)
The resistace to electrical current flow increases with it. Causing the electrode to heat
Minimum distortion due to low heat input
Gives arc voltage values to the control system of the feeder

44. What is an advantage of pulsed arc transfer with GMAW?
If you dont know this check your phone
Dry ice can form within the flow control openings and cause blockage of shielding gas
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
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

45. What are the 2 types of wire feeders available?
The Arc voltage
Wire feed speed
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

46. What is the key advantage of short circuiting transfer?
Aluminum wire
Minimum distortion due to low heat input
Speed of the feed motor and - starting / stopping electrode feed
To prevent leakage - Carbon Dioxide (CO2)

47. What is a solenoid valve and what actuates it?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Flux cored wires
Wire feed speed - Voltage control

48. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Constant- speed wire feeders and Voltage- sennsing wire feeders
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Generally not as accurate
Motor driven generators - Transformer rectifiers - and Inverter designs

49. What is the purpose of the shielding gas used in GMAW?
Controls the rate of flow of a shielding gas to the gun nozzle
Penetration and burn - off rate of the electrode
Shielding the molten weld metal from atmospheric contamination
To limit the short circuiting current so that spatter is reduced

50. Why is a fiber washer required and what cylinder gas requires it?
Wire feed speed
Duty cycle
Penetration and burn - off rate of the electrode
To prevent leakage - Carbon Dioxide (CO2)