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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.
Don't refresh. All questions and answers are randomly picked and ordered every time you load a test.

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. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
Wire feed speed
Motor driven generators - Transformer rectifiers - and Inverter designs
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
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2. What wire are knurled drive rolls most commonly used on?
Controls the rate of flow of a shielding gas to the gun nozzle
Guns
Flux cored wires
Pressure - The rate of flow of a shielding gas

3. List the three methods of metal transfer with GMAW
(DCEP) Direct Current Electrode Positive or Reverse polarity
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Short- circuiting transfer - Globular transfer - Spray transfer
Constant current (CC)

4. With straight polarity where is 2/3 of the arc energy?
Minutes of elapsed time continually run (out of 10 minutes)
The negative side of a welding unit
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Generally not as accurate

5. What does the abbreviation NEMA stand for?
National Electrical Manufactures Association
If you dont know this check your phone
The negative side of a welding unit
Reducing the gas source pressure to a constant working pressure

6. Why is a line heater required when using GMAW?
Penetration and burn - off rate of the electrode
Dry ice can form within the flow control openings and cause blockage of shielding gas
Pressure - The rate of flow of a shielding gas
Guns

7. What controls the wire speed on a voltage sensing wire feeder?
By there current carrying capacity
Reducing the gas source pressure to a constant working pressure
Constant- speed wire feeders and Voltage- sennsing wire feeders
The Arc voltage

8. What is the purpose of the shielding gas used in GMAW?
The negative side of a welding unit
Shielding the molten weld metal from atmospheric contamination
Puddle fluidity
Pressure - The rate of flow of a shielding gas

9. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
National Electrical Manufactures Association
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
5.8 to 12.5 L/min

10. Give a description of 'pinch effect'
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
The resistace to electrical current flow increases with it. Causing the electrode to heat
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
Duty cycle

11. A 10 minute cycle of welding time vs cooling time a given machine can handle.
12 to 22 arc volts
3
Pressure - The rate of flow of a shielding gas
Duty cycle

12. List several industries that would use GMAW
Guns
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Speed of the feed motor and - starting / stopping electrode feed
Pressure vessels and the piping industry

13. Why must CO2 cylinders be used in the vertical position?
To prevent drawing of liquid CO2 (Carbon Dioxide)
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 to 200 times per second
To prevent leakage - Carbon Dioxide (CO2)

14. List the basic equipment requirements for the GMAW process
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
To prevent drawing of liquid CO2 (Carbon Dioxide)
AWS and CSA
Insufficient current to melt the wire off cleanly

15. What controls amperage when using GMAW?
1/4 inch to 1/2 inch
Guns
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Wire feed speed

16. What 2 organizations designate specifications for GMAW wires?
AWS and CSA
85%
Pressure vessels and the piping industry
Shielding the molten weld metal from atmospheric contamination

17. A pull type drive system is usually used on what type of material?
Minutes of elapsed time continually run (out of 10 minutes)
The resistace to electrical current flow increases with it. Causing the electrode to heat
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Aluminum wire

18. What is another term for electrode holders for GMAW?
The negative side of a welding unit
Guns
Wire feed speed - Voltage control
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

19. 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)
Penetration and burn - off rate of the electrode
Spatter problems and poor weld appearance
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

20. Why is a fiber washer required and what cylinder gas requires it?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
To prevent leakage - Carbon Dioxide (CO2)
Dry ice can form within the flow control openings and cause blockage of shielding gas
20 to 200 times per second

21. Give a brief description of the GMAW process
1/4 inch to 1/2 inch
Welding process that joins metals by heating them with an electric arc
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Aluminum wire

22. 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
To limit the short circuiting current so that spatter is reduced
The negative side of a welding unit
12 to 22 arc volts

23. What is a typical flow rate of CO2 for short circuit transfer?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
5.8 to 12.5 L/min
When the filler wire is in direct contract with the base metal
Motor driven generators - Transformer rectifiers - and Inverter designs

24. Regulators control_____________ flowmeters SHOW____________.
Pressure - The rate of flow of a shielding gas
20 to 200 times per second
(DCEP) Direct Current Electrode Positive or Reverse polarity
DCEP (Direct Current Electrode Positive) Reverse Polarity

25. When is the metal transferred with short circuit transfer?
When the filler wire is in direct contract with the base metal
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
SMAW - GTAW
Welding process that joins metals by heating them with an electric arc

26. What is an advantage of pulsed arc transfer with GMAW?
The Arc voltage
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Penetration and burn - off rate of the electrode
To limit the short circuiting current so that spatter is reduced

27. 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
3
When the filler wire is in direct contract with the base metal
Cause flaking - which can clog the liner and contact tube

28. What is the maximum distance that hard wire can be successfully pushed?
85%
(DCEP) Direct Current Electrode Positive or Reverse polarity
The time rate of response for the current rise and fall
15 feet (4.5 meters)

29. What type of power source is commonly used with a voltage sensing wire feeder?
1/4 inch to 1/2 inch
Constant current (CC)
Voltage is the force that overcomes resistance to allow amperage flow
Gas metal arc welding

30. 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
Voltage is the force that overcomes resistance to allow amperage flow
National Electrical Manufactures Association
Wire feed speed - Voltage control

31. What does inductance control?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
The time rate of response for the current rise and fall
Controls the rate of flow of a shielding gas to the gun nozzle
Reducing the gas source pressure to a constant working pressure

32. What processes are constant current (CC) power sources designed to be used with?
Shielding the molten weld metal from atmospheric contamination
SMAW - GTAW
Voltage is the force that overcomes resistance to allow amperage flow
Duty cycle

33. What effect does increasing and decreasing the inductance have on the weld?
Aluminum wire
Voltage is the force that overcomes resistance to allow amperage flow
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

34. What 2 controls are found on a GMAW set- up?
The time rate of response for the current rise and fall
Wire feed speed - Voltage control
National Electrical Manufactures Association
...

35. In the GMAW process what does voltage control?
By there current carrying capacity
Minutes of elapsed time continually run (out of 10 minutes)
Pressure - The rate of flow of a shielding gas
Puddle fluidity

36. What does a flowmeter do and what does it measure?
20 to 200 times per second
If you dont know this check your phone
Controls the rate of flow of a shielding gas to the gun nozzle
Constant current (CC)

37. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
Spatter problems and poor weld appearance
85%
DCEP (Direct Current Electrode Positive) Reverse Polarity
Wire feed speed - Voltage control

38. What current and polarity is generally used with GMAW?
To limit the short circuiting current so that spatter is reduced
DCEP (Direct Current Electrode Positive) Reverse Polarity
When the filler wire is in direct contract with the base metal
Duty cycle

39. What is the main purpose of 'slope'?
Voltage is the force that overcomes resistance to allow amperage flow
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
To limit the short circuiting current so that spatter is reduced
Shielding the molten weld metal from atmospheric contamination

40. What is the key advantage of short circuiting transfer?
Minimum distortion due to low heat input
Generally not as accurate
Speed of the feed motor and - starting / stopping electrode feed
V groove or U groove

41. List 3 forms compressed gases may be supplied for welding
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
Gives arc voltage values to the control system of the feeder
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

42. What happens when the electrode extension is increased?
The resistace to electrical current flow increases with it. Causing the electrode to heat
Minutes of elapsed time continually run (out of 10 minutes)
The Arc voltage
Dry ice can form within the flow control openings and cause blockage of shielding gas

43. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
Generally not as accurate
Shielding the molten weld metal from atmospheric contamination
Cause flaking - which can clog the liner and contact tube
(DCEP) Direct Current Electrode Positive or Reverse polarity

44. What is the effect of too much slope?
Insufficient current to melt the wire off cleanly
Cause flaking - which can clog the liner and contact tube
To prevent leakage - Carbon Dioxide (CO2)
Guns

45. In the GMAW process what does amperage control?
Minimum distortion due to low heat input
Constant- speed wire feeders and Voltage- sennsing wire feeders
(DCEP) Direct Current Electrode Positive or Reverse polarity
Penetration and burn - off rate of the electrode

46. What is the recommended electrode stick- out for .035 solid wire?
Guns
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
To limit the short circuiting current so that spatter is reduced

47. What does the wire feeder control?
Speed of the feed motor and - starting / stopping electrode feed
Duty cycle
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
National Electrical Manufactures Association

48. What power sources are used with the GMAW Process?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Puddle fluidity
Motor driven generators - Transformer rectifiers - and Inverter designs
Short- circuiting transfer - Globular transfer - Spray transfer

49. What are the 2 types of wire feeders available?
The Arc voltage
Constant- speed wire feeders and Voltage- sennsing wire feeders
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Penetration and burn - off rate of the electrode

50. What type of power source is used with a constant speed wire feeder?
The resistace to electrical current flow increases with it. Causing the electrode to heat
To prevent leakage - Carbon Dioxide (CO2)
The Arc voltage
Constant voltage (CV)