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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.
Welding process that joins metals by heating them with an electric arc
Voltage is the force that overcomes resistance to allow amperage flow
3
When the filler wire is in direct contract with the base metal

2. What effect does increasing and decreasing the inductance have on the weld?
Reducing the gas source pressure to a constant working pressure
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
The resistace to electrical current flow increases with it. Causing the electrode to heat

3. What is a typical flow rate of CO2 for short circuit transfer?
Constant voltage (CV)
5.8 to 12.5 L/min
When the filler wire is in direct contract with the base metal
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

4. What type of power source is commonly used with a voltage sensing wire feeder?
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AWS and CSA
Constant current (CC)
The Arc voltage

5. List several industries that would use GMAW
Pressure vessels and the piping industry
15 feet (4.5 meters)
20 to 200 times per second
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6. What power sources are used with the GMAW Process?
Short- circuiting transfer - Globular transfer - Spray transfer
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
1/4 inch to 1/2 inch
Motor driven generators - Transformer rectifiers - and Inverter designs

7. Why must CO2 cylinders be used in the vertical position?
The time rate of response for the current rise and fall
To prevent drawing of liquid CO2 (Carbon Dioxide)
These terms are quite restrictive and often technically incorrect
The negative side of a welding unit

8. What is the purpose of the shielding gas used in GMAW?
SMAW - GTAW
15 feet (4.5 meters)
Shielding the molten weld metal from atmospheric contamination
Wire feed speed - Voltage control

9. What is the preferred drive roll design for solid wires?
Minimum distortion due to low heat input
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V groove or U groove
National Electrical Manufactures Association

10. What is the required arc voltage used for short circuit transfer?
Guns
Reducing the gas source pressure to a constant working pressure
12 to 22 arc volts
Higher 26 to 35 arc volts

11. Why is a fiber washer required and what cylinder gas requires it?
Constant voltage (CV)
To prevent leakage - Carbon Dioxide (CO2)
Motor driven generators - Transformer rectifiers - and Inverter designs
Controls the rate of flow of a shielding gas to the gun nozzle

12. What controls the wire speed on a voltage sensing wire 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
Flux cored wires
The Arc voltage
Generally not as accurate

13. In the GMAW process what does amperage control?
When the filler wire is in direct contract with the base metal
15 feet (4.5 meters)
Penetration and burn - off rate of the electrode
Insufficient current to melt the wire off cleanly

14. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
(DCEP) Direct Current Electrode Positive or Reverse polarity
85%
Wire feed speed - Voltage control
Cause flaking - which can clog the liner and contact tube

15. What is the key advantage of short circuiting transfer?
Minimum distortion due to low heat input
Guns
Minutes of elapsed time continually run (out of 10 minutes)
Short- circuiting transfer - Globular transfer - Spray transfer

16. Regulators control_____________ flowmeters SHOW____________.
Duty cycle
Pressure - The rate of flow of a shielding gas
The Arc voltage
Reducing the gas source pressure to a constant working pressure

17. What is the main purpose of 'slope'?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Wire feeds smoothly (yet will slip should a problem occur in the gun)
To limit the short circuiting current so that spatter is reduced

18. What does inductance control?
1/4 inch to 1/2 inch
Guns
Welding process that joins metals by heating them with an electric arc
The time rate of response for the current rise and fall

19. What is the recommended electrode stick- out for .035 solid wire?
1/4 inch to 1/2 inch
Controls the rate of flow of a shielding gas to the gun nozzle
Gas metal arc welding
Constant current (CC)

20. List the basic equipment requirements for the GMAW process
Penetration and burn - off rate of the electrode
(DCEP) Direct Current Electrode Positive or Reverse polarity
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Puddle fluidity

21. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Generally not as accurate
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Cause flaking - which can clog the liner and contact tube
V groove or U groove

22. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Aluminum wire
Gas metal arc welding
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23. What does voltage do in an electrical circuit?
Voltage is the force that overcomes resistance to allow amperage flow
Motor driven generators - Transformer rectifiers - and Inverter designs
Generally not as accurate
15 feet (4.5 meters)

24. What processes are constant current (CC) power sources designed to be used with?
Gas metal arc welding
Welding process that joins metals by heating them with an electric arc
Controls the rate of flow of a shielding gas to the gun nozzle
SMAW - GTAW

25. How are GMAW guns rated?
V groove or U groove
Wire feeds smoothly (yet will slip should a problem occur in the gun)
When the filler wire is in direct contract with the base metal
By there current carrying capacity

26. What is the effect of too much slope?
Gives arc voltage values to the control system of the feeder
5.8 to 12.5 L/min
The time rate of response for the current rise and fall
Insufficient current to melt the wire off cleanly

27. How many times per second does short circuiting take place?
Welding process that joins metals by heating them with an electric arc
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
By there current carrying capacity
20 to 200 times per second

28. 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
Short- circuiting transfer - Globular transfer - Spray transfer
Wire feed speed - Voltage control
...

29. What type of power source is used with a constant speed wire feeder?
Constant voltage (CV)
By there current carrying capacity
Motor driven generators - Transformer rectifiers - and Inverter designs
DCEP (Direct Current Electrode Positive) Reverse Polarity

30. List 3 wire drive systems and give a short description of each
12 to 22 arc volts
These terms are quite restrictive and often technically incorrect
Pressure - The rate of flow of a shielding gas
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

31. What output on the welding machine is used to rate the duty cycle?
1/4 inch to 1/2 inch
Flux cored wires
Minutes of elapsed time continually run (out of 10 minutes)
The Arc voltage

32. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
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Constant voltage (CV)
(DCEP) Direct Current Electrode Positive or Reverse polarity
The negative side of a welding unit

33. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Wire feed speed
Puddle fluidity
Penetration and burn - off rate of the electrode
Duty cycle

34. Draw a typical volt amp curve for a machine that is designed for GMAW
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Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Puddle fluidity
Gives arc voltage values to the control system of the feeder

35. What does the abbreviation NEMA stand for?
Motor driven generators - Transformer rectifiers - and Inverter designs
National Electrical Manufactures Association
Constant voltage (CV)
Cause flaking - which can clog the liner and contact tube

36. When is the metal transferred with short circuit transfer?
To limit the short circuiting current so that spatter is reduced
Controls the rate of flow of a shielding gas to the gun nozzle
V groove or U groove
When the filler wire is in direct contract with the base metal

37. What does the term GMAW identify?
Gas metal arc welding
Short- circuiting transfer - Globular transfer - Spray transfer
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Minimum distortion due to low heat input

38. What does a flowmeter do and what does it measure?
If you dont know this check your phone
Shielding the molten weld metal from atmospheric contamination
Controls the rate of flow of a shielding gas to the gun nozzle
Wire feed speed

39. What wire are knurled drive rolls most commonly used on?
Flux cored wires
Constant current (CC)
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
Penetration and burn - off rate of the electrode

40. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
The time rate of response for the current rise and fall
...
Pressure vessels and the piping industry
Gas metal arc welding

41. List the factors that determine the mode of metal transfer
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
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 - Voltage control
V groove or U groove

42. What does the wire feeder control?
Speed of the feed motor and - starting / stopping electrode feed
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
Dry ice can form within the flow control openings and cause blockage of shielding gas

43. A pull type drive system is usually used on what type of material?
The Arc voltage
Motor driven generators - Transformer rectifiers - and Inverter designs
Aluminum wire
National Electrical Manufactures Association

44. What is the purpose of a regulator and what does it indicate on its gauges?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
3
Gives arc voltage values to the control system of the feeder
Reducing the gas source pressure to a constant working pressure

45. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Higher 26 to 35 arc volts
The resistace to electrical current flow increases with it. Causing the electrode to heat
Wire feed speed
Speed of the feed motor and - starting / stopping electrode feed

46. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
5.8 to 12.5 L/min
If you dont know this check your phone
Gives arc voltage values to the control system of the feeder
To prevent leakage - Carbon Dioxide (CO2)

47. What 2 controls are found on a GMAW set- up?
Constant current (CC)
Aluminum wire
Wire feed speed - Voltage control
The time rate of response for the current rise and fall

48. What current and polarity is generally used with GMAW?
Welding process that joins metals by heating them with an electric arc
DCEP (Direct Current Electrode Positive) Reverse Polarity
Duty cycle
Constant voltage (CV)

49. What is an advantage of pulsed arc transfer with GMAW?
National Electrical Manufactures Association
DCEP (Direct Current Electrode Positive) Reverse Polarity
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

50. What is a solenoid valve and what actuates it?
Insufficient current to melt the wire off cleanly
...
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
The time rate of response for the current rise and fall