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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. What is the recommended electrode stick- out for .035 solid wire?
If you dont know this check your phone
1/4 inch to 1/2 inch
Flux cored wires
3

2. Give a brief description of the GMAW process
Welding process that joins metals by heating them with an electric arc
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
Controls the rate of flow of a shielding gas to the gun nozzle

3. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
The Arc voltage
Higher 26 to 35 arc volts
Duty cycle
Voltage is the force that overcomes resistance to allow amperage flow

4. What is a solenoid valve and what actuates it?
To limit the short circuiting current so that spatter is reduced
Shielding the molten weld metal from atmospheric contamination
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Wire feed speed

5. With straight polarity where is 2/3 of the arc energy?
The negative side of a welding unit
Constant current (CC)
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
These terms are quite restrictive and often technically incorrect

6. What wire are knurled drive rolls most commonly used on?
Higher 26 to 35 arc volts
85%
Flux cored wires
When the filler wire is in direct contract with the base metal

7. When is the metal transferred with short circuit transfer?
Gas metal arc welding
20 to 200 times per second
Speed of the feed motor and - starting / stopping electrode feed
When the filler wire is in direct contract with the base metal

8. What is an advantage of pulsed arc transfer with GMAW?
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
Controls the rate of flow of a shielding gas to the gun nozzle
The time rate of response for the current rise and fall

9. Why is a fiber washer required and what cylinder gas requires it?
Constant voltage (CV)
To prevent leakage - Carbon Dioxide (CO2)
12 to 22 arc volts
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

10. What does inductance control?
The time rate of response for the current rise and fall
Reducing the gas source pressure to a constant working pressure
Gives arc voltage values to the control system of the feeder
Voltage is the force that overcomes resistance to allow amperage flow

11. What is the effect of too much slope?
To limit the short circuiting current so that spatter is reduced
Motor driven generators - Transformer rectifiers - and Inverter designs
Insufficient current to melt the wire off cleanly
Minutes of elapsed time continually run (out of 10 minutes)

12. List 3 wire drive systems and give a short description of each
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
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
5.8 to 12.5 L/min
To prevent leakage - Carbon Dioxide (CO2)

13. What processes are constant current (CC) power sources designed to be used with?
Penetration and burn - off rate of the electrode
Controls the rate of flow of a shielding gas to the gun nozzle
5.8 to 12.5 L/min
SMAW - GTAW

14. What does the term GMAW identify?
Minimum distortion due to low heat input
Gas metal arc welding
The time rate of response for the current rise and fall
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

15. In the GMAW process what does amperage control?
85%
When the filler wire is in direct contract with the base metal
Penetration and burn - off rate of the electrode
Generally not as accurate

16. What is the main purpose of 'slope'?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
To limit the short circuiting current so that spatter is reduced
Wire feed speed
National Electrical Manufactures Association

17. What is another term for electrode holders for GMAW?
Guns
By there current carrying capacity
1/4 inch to 1/2 inch
Penetration and burn - off rate of the electrode

18. How many times per second does short circuiting take place?
Puddle fluidity
Shielding the molten weld metal from atmospheric contamination
Wire feed speed - Voltage control
20 to 200 times per second

19. What happens when the electrode extension is increased?
The resistace to electrical current flow increases with it. Causing the electrode to heat
Minimum distortion due to low heat input
Welding process that joins metals by heating them with an electric arc
By there current carrying capacity

20. What does a flowmeter do and what does it measure?
Controls the rate of flow of a shielding gas to the gun nozzle
15 feet (4.5 meters)
Pressure vessels and the piping industry
Minutes of elapsed time continually run (out of 10 minutes)

21. Give a description of 'pinch effect'
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Constant voltage (CV)
By there current carrying capacity

22. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
Speed of the feed motor and - starting / stopping electrode feed
...
Wire feed speed - Voltage control
By there current carrying capacity

23. 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
Motor driven generators - Transformer rectifiers - and Inverter designs
To prevent leakage - Carbon Dioxide (CO2)
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

24. What effect does increasing and decreasing the inductance have on the weld?
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
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
Puddle fluidity
Pressure vessels and the piping industry

25. Regulators control_____________ flowmeters SHOW____________.
The resistace to electrical current flow increases with it. Causing the electrode to heat
Pressure - The rate of flow of a shielding gas
Constant current (CC)
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

26. Draw a typical volt amp curve for a machine that is designed for GMAW
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
If you dont know this check your phone
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Pressure vessels and the piping industry

27. What does voltage do in an electrical circuit?
By there current carrying capacity
Voltage is the force that overcomes resistance to allow amperage flow
Minimum distortion due to low heat input
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

28. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
85%
12 to 22 arc volts
The resistace to electrical current flow increases with it. Causing the electrode to heat
Controls the rate of flow of a shielding gas to the gun nozzle

29. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Generally not as accurate
To prevent leakage - Carbon Dioxide (CO2)
Penetration and burn - off rate of the electrode
5.8 to 12.5 L/min

30. What is the purpose of the shielding gas used in GMAW?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Motor driven generators - Transformer rectifiers - and Inverter designs
These terms are quite restrictive and often technically incorrect
Shielding the molten weld metal from atmospheric contamination

31. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
3
The time rate of response for the current rise and fall
Higher 26 to 35 arc volts
Wire feeds smoothly (yet will slip should a problem occur in the gun)

32. What 2 organizations designate specifications for GMAW wires?
The negative side of a welding unit
AWS and CSA
To prevent leakage - Carbon Dioxide (CO2)
Insufficient current to melt the wire off cleanly

33. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Cause flaking - which can clog the liner and contact tube
Speed of the feed motor and - starting / stopping electrode feed
The resistace to electrical current flow increases with it. Causing the electrode to heat

34. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Cause flaking - which can clog the liner and contact tube
If you dont know this check your phone
Duty cycle

35. Why must CO2 cylinders be used in the vertical position?
Short- circuiting transfer - Globular transfer - Spray transfer
Higher 26 to 35 arc volts
To prevent drawing of liquid CO2 (Carbon Dioxide)
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

36. What type of power source is used with a constant speed wire feeder?
Constant current (CC)
The resistace to electrical current flow increases with it. Causing the electrode to heat
Constant voltage (CV)
Wire feeds smoothly (yet will slip should a problem occur in the gun)

37. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Constant- speed wire feeders and Voltage- sennsing wire feeders
Gives arc voltage values to the control system of the feeder

38. In the GMAW process what does voltage control?
Higher 26 to 35 arc volts
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Puddle fluidity
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

39. List the three methods of metal transfer with GMAW
Constant voltage (CV)
Dry ice can form within the flow control openings and cause blockage of shielding gas
Short- circuiting transfer - Globular transfer - Spray transfer
Reducing the gas source pressure to a constant working pressure

40. What are the 2 types of wire feeders available?
Motor driven generators - Transformer rectifiers - and Inverter designs
To prevent leakage - Carbon Dioxide (CO2)
Constant- speed wire feeders and Voltage- sennsing wire feeders
20 to 200 times per second

41. List the factors that determine the mode of metal transfer
Minutes of elapsed time continually run (out of 10 minutes)
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Penetration and burn - off rate of the electrode
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

42. What controls the wire speed on a voltage sensing wire feeder?
The Arc voltage
Penetration and burn - off rate of the electrode
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

43. What does the abbreviation NEMA stand for?
If you dont know this check your phone
To prevent drawing of liquid CO2 (Carbon Dioxide)
National Electrical Manufactures Association
To prevent leakage - Carbon Dioxide (CO2)

44. Why is globular transfer generally avoided with GMAW?
12 to 22 arc volts
Constant- speed wire feeders and Voltage- sennsing wire feeders
Spatter problems and poor weld appearance
Duty cycle

45. What would be an indication that the drive roll pressure is adjusted correctly?
Speed of the feed motor and - starting / stopping electrode feed
Penetration and burn - off rate of the electrode
Motor driven generators - Transformer rectifiers - and Inverter designs
Wire feeds smoothly (yet will slip should a problem occur in the gun)

46. What does the wire feeder control?
3
Cause flaking - which can clog the liner and contact tube
Speed of the feed motor and - starting / stopping electrode feed
1/4 inch to 1/2 inch

47. What is a typical flow rate of CO2 for short circuit transfer?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Gives arc voltage values to the control system of the feeder
5.8 to 12.5 L/min
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

48. What is the preferred drive roll design for solid wires?
Cause flaking - which can clog the liner and contact tube
Wire feed speed
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
V groove or U groove

49. List the basic equipment requirements for the GMAW process
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Short- circuiting transfer - Globular transfer - Spray transfer
20 to 200 times per second
Reducing the gas source pressure to a constant working pressure

50. What output on the welding machine is used to rate the duty cycle?
Minutes of elapsed time continually run (out of 10 minutes)
Generally not as accurate
Gas metal arc welding
20 to 200 times per second