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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. Why must CO2 cylinders be used in the vertical position?
The resistace to electrical current flow increases with it. Causing the electrode to heat
To prevent drawing of liquid CO2 (Carbon Dioxide)
The time rate of response for the current rise and fall
Shielding the molten weld metal from atmospheric contamination

2. What controls the wire speed on a voltage sensing wire feeder?
Constant current (CC)
Generally not as accurate
Speed of the feed motor and - starting / stopping electrode feed
The Arc voltage

3. Why is a fiber washer required and what cylinder gas requires it?
Shielding the molten weld metal from atmospheric contamination
Guns
To prevent leakage - Carbon Dioxide (CO2)
The negative side of a welding unit

4. List 3 wire drive systems and give a short description of each
12 to 22 arc volts
Duty cycle
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
Controls the rate of flow of a shielding gas to the gun nozzle

5. What is the effect of too much slope?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Insufficient current to melt the wire off cleanly
Wire feed speed
Reducing the gas source pressure to a constant working pressure

6. What effect does increasing and decreasing the inductance have on the weld?
...
Spatter problems and poor weld appearance
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

7. What is a solenoid valve and what actuates it?
National Electrical Manufactures Association
20 to 200 times per second
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

8. What does a flowmeter do and what does it measure?
5.8 to 12.5 L/min
The time rate of response for the current rise and fall
Constant voltage (CV)
Controls the rate of flow of a shielding gas to the gun nozzle

9. List the three methods of metal transfer with GMAW
Short- circuiting transfer - Globular transfer - Spray transfer
Reducing the gas source pressure to a constant working pressure
Pressure - The rate of flow of a shielding gas
Voltage is the force that overcomes resistance to allow amperage flow

10. What is the purpose of a regulator and what does it indicate on its gauges?
Puddle fluidity
Reducing the gas source pressure to a constant working pressure
To prevent drawing of liquid CO2 (Carbon Dioxide)
Wire feed speed - Voltage control

11. What does voltage do in an electrical circuit?
Welding process that joins metals by heating them with an electric arc
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Shielding the molten weld metal from atmospheric contamination
Voltage is the force that overcomes resistance to allow amperage flow

12. What processes are constant current (CC) power sources designed to be used with?
Constant voltage (CV)
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
SMAW - GTAW

13. What 2 organizations designate specifications for GMAW wires?
Short- circuiting transfer - Globular transfer - Spray transfer
Minutes of elapsed time continually run (out of 10 minutes)
AWS and CSA
5.8 to 12.5 L/min

14. What is the main purpose of 'slope'?
National Electrical Manufactures Association
To limit the short circuiting current so that spatter is reduced
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
5.8 to 12.5 L/min

15. What controls amperage when using GMAW?
Dry ice can form within the flow control openings and cause blockage of shielding gas
Wire feed speed
Shielding the molten weld metal from atmospheric contamination
Controls the rate of flow of a shielding gas to the gun nozzle

16. What type of power source is used with a constant speed wire feeder?
Constant current (CC)
Constant voltage (CV)
To prevent leakage - Carbon Dioxide (CO2)
Penetration and burn - off rate of the electrode

17. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Gas metal arc welding
20 to 200 times per second
Gives arc voltage values to the control system of the feeder
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. How many times per second does short circuiting take place?
1/4 inch to 1/2 inch
20 to 200 times per second
Speed of the feed motor and - starting / stopping electrode feed
Higher 26 to 35 arc volts

19. List the factors that determine the mode of metal transfer
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
15 feet (4.5 meters)
The Arc voltage
3

20. 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
1/4 inch to 1/2 inch
Puddle fluidity
To prevent leakage - Carbon Dioxide (CO2)

21. What wire are knurled drive rolls most commonly used on?
Flux cored wires
The resistace to electrical current flow increases with it. Causing the electrode to heat
20 to 200 times per second
Wire feeds smoothly (yet will slip should a problem occur in the gun)

22. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
DCEP (Direct Current Electrode Positive) Reverse Polarity
3
1/4 inch to 1/2 inch
Constant voltage (CV)

23. What does inductance control?
1/4 inch to 1/2 inch
The time rate of response for the current rise and fall
By there current carrying capacity
85%

24. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
Wire feed speed
Speed of the feed motor and - starting / stopping electrode feed
Motor driven generators - Transformer rectifiers - and Inverter designs
If you dont know this check your phone

25. With straight polarity where is 2/3 of the arc energy?
Dry ice can form within the flow control openings and cause blockage of shielding gas
1/4 inch to 1/2 inch
AWS and CSA
The negative side of a welding unit

26. List the basic equipment requirements for the GMAW process
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Duty cycle
The Arc voltage
Minimum distortion due to low heat input

27. What is a typical flow rate of CO2 for short circuit transfer?
5.8 to 12.5 L/min
The negative side of a welding unit
...
To prevent leakage - Carbon Dioxide (CO2)

28. List 3 forms compressed gases may be supplied for welding
5.8 to 12.5 L/min
These terms are quite restrictive and often technically incorrect
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Flux cored wires

29. How are GMAW guns rated?
Minutes of elapsed time continually run (out of 10 minutes)
By there current carrying capacity
Generally not as accurate
Insufficient current to melt the wire off cleanly

30. 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
Shielding the molten weld metal from atmospheric contamination
V groove or U groove

31. What would be an indication that the drive roll pressure is adjusted correctly?
Pressure - The rate of flow of a shielding gas
Insufficient current to melt the wire off cleanly
Speed of the feed motor and - starting / stopping electrode feed
Wire feeds smoothly (yet will slip should a problem occur in the gun)

32. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Generally not as accurate
Gas metal arc welding
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
To prevent leakage - Carbon Dioxide (CO2)

33. What does the wire feeder control?
Pressure vessels and the piping industry
Speed of the feed motor and - starting / stopping electrode feed
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

34. What type of power source is commonly used with a voltage sensing wire feeder?
Constant current (CC)
Voltage is the force that overcomes resistance to allow amperage flow
Duty cycle
If you dont know this check your phone

35. Regulators control_____________ flowmeters SHOW____________.
By there current carrying capacity
Generally not as accurate
Gives arc voltage values to the control system of the feeder
Pressure - The rate of flow of a shielding gas

36. Draw a typical volt amp curve for a machine that is designed for GMAW
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
DCEP (Direct Current Electrode Positive) Reverse Polarity
If you dont know this check your phone
Guns

37. What is the purpose of the shielding gas used in GMAW?
If you dont know this check your phone
Spatter problems and poor weld appearance
...
Shielding the molten weld metal from atmospheric contamination

38. What is the key advantage of short circuiting transfer?
Wire feed speed
Minimum distortion due to low heat input
Cause flaking - which can clog the liner and contact tube
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. What 2 controls are found on a GMAW set- up?
Wire feed speed - Voltage control
Speed of the feed motor and - starting / stopping electrode feed
Puddle fluidity
If you dont know this check your phone

40. What power sources are used with the GMAW Process?
(DCEP) Direct Current Electrode Positive or Reverse polarity
SMAW - GTAW
Wire feed speed - Voltage control
Motor driven generators - Transformer rectifiers - and Inverter designs

41. List several industries that would use GMAW
The negative side of a welding unit
Speed of the feed motor and - starting / stopping electrode feed
Pressure vessels and the piping industry
DCEP (Direct Current Electrode Positive) Reverse Polarity

42. What are the 2 types of wire feeders available?
Minutes of elapsed time continually run (out of 10 minutes)
Constant- speed wire feeders and Voltage- sennsing wire feeders
To limit the short circuiting current so that spatter is reduced
Cause flaking - which can clog the liner and contact tube

43. A pull type drive system is usually used on what type of material?
SMAW - GTAW
By there current carrying capacity
Spatter problems and poor weld appearance
Aluminum wire

44. What does the abbreviation NEMA stand for?
The Arc voltage
20 to 200 times per second
National Electrical Manufactures Association
Minutes of elapsed time continually run (out of 10 minutes)

45. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Dry ice can form within the flow control openings and cause blockage of shielding gas
If you dont know this check your phone
Voltage is the force that overcomes resistance to allow amperage flow
Duty cycle

46. What is the preferred drive roll design for solid wires?
V groove or U groove
Aluminum wire
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Shielding the molten weld metal from atmospheric contamination

47. Give a brief description of the GMAW process
Welding process that joins metals by heating them with an electric arc
Spatter problems and poor weld appearance
3
Wire feeds smoothly (yet will slip should a problem occur in the gun)

48. What does the term GMAW identify?
Voltage is the force that overcomes resistance to allow amperage flow
Gas metal arc welding
SMAW - GTAW
V groove or U groove

49. When is the metal transferred with short circuit transfer?
Pressure - The rate of flow of a shielding gas
Voltage is the force that overcomes resistance to allow amperage flow
(DCEP) Direct Current Electrode Positive or Reverse polarity
When the filler wire is in direct contract with the base metal

50. What is the recommended electrode stick- out for .035 solid wire?
Guns
To prevent leakage - Carbon Dioxide (CO2)
To prevent drawing of liquid CO2 (Carbon Dioxide)
1/4 inch to 1/2 inch