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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. List the three methods of metal transfer with GMAW
Penetration and burn - off rate of the electrode
By there current carrying capacity
Short- circuiting transfer - Globular transfer - Spray transfer
Constant current (CC)

2. What is the main purpose of 'slope'?
Constant current (CC)
15 feet (4.5 meters)
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 limit the short circuiting current so that spatter is reduced

3. In the GMAW process what does voltage control?
If you dont know this check your phone
Flux cored wires
Puddle fluidity
15 feet (4.5 meters)

4. What is the purpose of the shielding gas used in GMAW?
Guns
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Shielding the molten weld metal from atmospheric contamination

5. Give a brief description of the GMAW process
The Arc voltage
Constant voltage (CV)
5.8 to 12.5 L/min
Welding process that joins metals by heating them with an electric arc

6. What does the abbreviation NEMA stand for?
SMAW - GTAW
National Electrical Manufactures Association
Spatter problems and poor weld appearance
The time rate of response for the current rise and fall

7. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
The Arc voltage
Insufficient current to melt the wire off cleanly
V groove or U groove
3

8. What current and polarity is generally used with GMAW?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Voltage is the force that overcomes resistance to allow amperage flow
When the filler wire is in direct contract with the base metal
Wire feeds smoothly (yet will slip should a problem occur in the gun)

9. Draw a typical volt amp curve for a machine that is designed for GMAW
Voltage is the force that overcomes resistance to allow amperage flow
Wire feeds smoothly (yet will slip should a problem occur in the gun)
If you dont know this check your phone
The negative side of a welding unit

10. When is the metal transferred with short circuit transfer?
AWS and CSA
When the filler wire is in direct contract with the base metal
By there current carrying capacity
Voltage is the force that overcomes resistance to allow amperage flow

11. What output on the welding machine is used to rate the duty cycle?
15 feet (4.5 meters)
Pressure vessels and the piping industry
Minutes of elapsed time continually run (out of 10 minutes)
Welding process that joins metals by heating them with an electric arc

12. What controls amperage when using GMAW?
When the filler wire is in direct contract with the base metal
Wire feed speed
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Voltage is the force that overcomes resistance to allow amperage flow

13. List 3 wire drive systems and give a short description of each
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
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
Constant voltage (CV)

14. What does the wire feeder control?
Minutes of elapsed time continually run (out of 10 minutes)
Wire feed speed
Reducing the gas source pressure to a constant working pressure
Speed of the feed motor and - starting / stopping electrode feed

15. What 2 organizations designate specifications for GMAW wires?
Shielding the molten weld metal from atmospheric contamination
AWS and CSA
Constant- speed wire feeders and Voltage- sennsing wire feeders
Motor driven generators - Transformer rectifiers - and Inverter designs

16. What does a flowmeter do and what does it measure?
Pressure vessels and the piping industry
Aluminum wire
SMAW - GTAW
Controls the rate of flow of a shielding gas to the gun nozzle

17. Why is a fiber washer required and what cylinder gas requires it?
Guns
To prevent leakage - Carbon Dioxide (CO2)
(DCEP) Direct Current Electrode Positive or Reverse polarity
Duty cycle

18. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Cause flaking - which can clog the liner and contact tube
Penetration and burn - off rate of the electrode
Constant voltage (CV)
Aluminum wire

19. What is the key advantage of short circuiting transfer?
Minimum distortion due to low heat input
Spatter problems and poor weld appearance
DCEP (Direct Current Electrode Positive) Reverse Polarity
Duty cycle

20. What is a solenoid valve and what actuates it?
V groove or U groove
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
By there current carrying capacity

21. What 2 controls are found on a GMAW set- up?
By there current carrying capacity
Wire feed speed - Voltage control
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

22. What effect does increasing and decreasing the inductance have on the weld?
20 to 200 times per second
(DCEP) Direct Current Electrode Positive or Reverse polarity
To limit the short circuiting current so that spatter is reduced
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

23. List 3 forms compressed gases may be supplied for welding
15 feet (4.5 meters)
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Puddle fluidity

24. What would be an indication that the drive roll pressure is adjusted correctly?
Aluminum wire
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
85%

25. What is the purpose of a regulator and what does it indicate on its gauges?
Minutes of elapsed time continually run (out of 10 minutes)
The Arc voltage
Reducing the gas source pressure to a constant working pressure
DCEP (Direct Current Electrode Positive) Reverse Polarity

26. What is an advantage of pulsed arc transfer with GMAW?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Welding process that joins metals by heating them with an electric arc
Minutes of elapsed time continually run (out of 10 minutes)

27. What processes are constant current (CC) power sources designed to be used with?
SMAW - GTAW
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
Flux cored wires

28. What is the required arc voltage used for short circuit transfer?
...
Puddle fluidity
12 to 22 arc volts
20 to 200 times per second

29. List several industries that would use GMAW
Pressure vessels and the piping industry
The resistace to electrical current flow increases with it. Causing the electrode to heat
Constant- speed wire feeders and Voltage- sennsing wire feeders
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

30. What type of power source is commonly used with a voltage sensing wire feeder?
Higher 26 to 35 arc volts
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
These terms are quite restrictive and often technically incorrect
Constant current (CC)

31. What is the preferred drive roll design for solid wires?
Minutes of elapsed time continually run (out of 10 minutes)
DCEP (Direct Current Electrode Positive) Reverse Polarity
V groove or U groove
The time rate of response for the current rise and fall

32. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
Speed of the feed motor and - starting / stopping electrode feed
Wire feed speed - Voltage control
Wire feeds smoothly (yet will slip should a problem occur in the gun)
If you dont know this check your phone

33. A 10 minute cycle of welding time vs cooling time a given machine can handle.
The Arc voltage
Dry ice can form within the flow control openings and cause blockage of shielding gas
Duty cycle
12 to 22 arc volts

34. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
Flux cored wires
Higher 26 to 35 arc volts
15 feet (4.5 meters)
85%

35. What does voltage do in an electrical circuit?
Voltage is the force that overcomes resistance to allow amperage flow
Dry ice can form within the flow control openings and cause blockage of 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
Higher 26 to 35 arc volts

36. How many times per second does short circuiting take place?
Welding process that joins metals by heating them with an electric arc
If you dont know this check your phone
To limit the short circuiting current so that spatter is reduced
20 to 200 times per second

37. List the factors that determine the mode of metal transfer
Reducing the gas source pressure to a constant working pressure
Aluminum wire
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Constant- speed wire feeders and Voltage- sennsing wire feeders

38. What is another term for electrode holders for GMAW?
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
Guns
To prevent drawing of liquid CO2 (Carbon Dioxide)

39. How are GMAW guns rated?
Motor driven generators - Transformer rectifiers - and Inverter designs
By there current carrying capacity
Aluminum wire
To prevent drawing of liquid CO2 (Carbon Dioxide)

40. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Higher 26 to 35 arc volts
Flux cored wires
Minimum distortion due to low heat input
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

41. What is the recommended electrode stick- out for .035 solid wire?
Flux cored wires
Gas metal arc welding
Aluminum wire
1/4 inch to 1/2 inch

42. List the basic equipment requirements for the GMAW process
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Pressure vessels and the piping industry
Insufficient current to melt the wire off cleanly
...

43. 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
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
85%
20 to 200 times per second

44. What is the effect of too much slope?
Insufficient current to melt the wire off cleanly
3
Generally not as accurate
V groove or U groove

45. What happens when the electrode extension is increased?
If you dont know this check your phone
The resistace to electrical current flow increases with it. Causing the electrode to heat
Shielding the molten weld metal from atmospheric contamination
The time rate of response for the current rise and fall

46. Why is globular transfer generally avoided with GMAW?
Voltage is the force that overcomes resistance to allow amperage flow
Spatter problems and poor weld appearance
Dry ice can form within the flow control openings and cause blockage of shielding gas
Constant current (CC)

47. Regulators control_____________ flowmeters SHOW____________.
Pressure - The rate of flow of a shielding gas
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Wire feed speed
Spatter problems and poor weld appearance

48. What is the disadvantage of the gauge preset type of regulator/flowmeter?
To limit the short circuiting current so that spatter is reduced
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
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

49. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
Wire feed speed - Voltage control
Controls the rate of flow of a shielding gas to the gun nozzle
Wire feeds smoothly (yet will slip should a problem occur in the gun)
...

50. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Flux cored wires
By there current carrying capacity
Gives arc voltage values to the control system of the feeder
Penetration and burn - off rate of the electrode