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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 term is used to describe when the workpiece is hooked to the negative pole on the power source?
Flux cored wires
To limit the short circuiting current so that spatter is reduced
12 to 22 arc volts
(DCEP) Direct Current Electrode Positive or Reverse polarity

2. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
The negative side of a welding unit
85%
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Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

3. What is the main purpose of 'slope'?
To limit the short circuiting current so that spatter is reduced
To prevent leakage - Carbon Dioxide (CO2)
Voltage is the force that overcomes resistance to allow amperage flow
Flux cored wires

4. What processes are constant current (CC) power sources designed to be used with?
The Arc voltage
Speed of the feed motor and - starting / stopping electrode feed
SMAW - GTAW
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

5. What type of power source is commonly used with a voltage sensing wire feeder?
Gas metal arc welding
Wire feed speed - Voltage control
Constant current (CC)
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

6. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Gives arc voltage values to the control system of the feeder
Duty cycle
12 to 22 arc volts
Voltage is the force that overcomes resistance to allow amperage flow

7. List 3 forms compressed gases may be supplied for welding
When the filler wire is in direct contract with the base metal
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Guns
20 to 200 times per second

8. Why is a fiber washer required and what cylinder gas requires it?
Spatter problems and poor weld appearance
Minutes of elapsed time continually run (out of 10 minutes)
Duty cycle
To prevent leakage - Carbon Dioxide (CO2)

9. What is the recommended electrode stick- out for .035 solid wire?
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
V groove or U groove
1/4 inch to 1/2 inch

10. What does the abbreviation NEMA stand for?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
National Electrical Manufactures Association
Constant voltage (CV)
Motor driven generators - Transformer rectifiers - and Inverter designs

11. What 2 organizations designate specifications for GMAW wires?
AWS and CSA
V groove or U groove
The resistace to electrical current flow increases with it. Causing the electrode to heat
Speed of the feed motor and - starting / stopping electrode feed

12. When is the metal transferred with short circuit transfer?
Reducing the gas source pressure to a constant working pressure
When the filler wire is in direct contract with the base metal
Short- circuiting transfer - Globular transfer - Spray transfer
Generally not as accurate

13. What does a flowmeter do and what does it measure?
Generally not as accurate
Higher 26 to 35 arc volts
Controls the rate of flow of a shielding gas to the gun nozzle
Guns

14. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
To prevent drawing of liquid CO2 (Carbon Dioxide)
...
Reducing the gas source pressure to a constant working pressure
Controls the rate of flow of a shielding gas to the gun nozzle

15. What happens when the electrode extension is increased?
The time rate of response for the current rise and fall
Short- circuiting transfer - Globular transfer - Spray transfer
The resistace to electrical current flow increases with it. Causing the electrode to heat
Dry ice can form within the flow control openings and cause blockage of shielding gas

16. List the three methods of metal transfer with GMAW
Short- circuiting transfer - Globular transfer - Spray transfer
Constant voltage (CV)
The Arc voltage
The resistace to electrical current flow increases with it. Causing the electrode to heat

17. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Minutes of elapsed time continually run (out of 10 minutes)
(DCEP) Direct Current Electrode Positive or Reverse polarity
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

18. What controls the wire speed on a voltage sensing wire feeder?
AWS and CSA
Generally not as accurate
The Arc voltage
By there current carrying capacity

19. What current and polarity is generally used with GMAW?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
DCEP (Direct Current Electrode Positive) Reverse Polarity
The negative side of a welding unit
Gas metal arc welding

20. What are the 2 types of wire feeders available?
To prevent leakage - Carbon Dioxide (CO2)
When the filler wire is in direct contract with the base metal
AWS and CSA
Constant- speed wire feeders and Voltage- sennsing wire feeders

21. How are GMAW guns rated?
Cause flaking - which can clog the liner and contact tube
Constant current (CC)
By there current carrying capacity
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

22. What 2 controls are found on a GMAW set- up?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
5.8 to 12.5 L/min
Wire feed speed - Voltage control
Pressure vessels and the piping industry

23. Give a brief description of the GMAW process
Minutes of elapsed time continually run (out of 10 minutes)
Welding process that joins metals by heating them with an electric arc
Minimum distortion due to low heat input
V groove or U groove

24. Draw a typical volt amp curve for a machine that is designed for GMAW
Speed of the feed motor and - starting / stopping electrode feed
Duty cycle
Shielding the molten weld metal from atmospheric contamination
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25. What type of power source is used with a constant speed wire feeder?
Constant voltage (CV)
Welding process that joins metals by heating them with an electric arc
Reducing the gas source pressure to a constant working pressure
Shielding the molten weld metal from atmospheric contamination

26. How many times per second does short circuiting take place?
20 to 200 times per second
Voltage is the force that overcomes resistance to allow amperage flow
Short- circuiting transfer - Globular transfer - Spray transfer
5.8 to 12.5 L/min

27. In the GMAW process what does voltage control?
Puddle fluidity
To prevent drawing of liquid CO2 (Carbon Dioxide)
V groove or U groove
AWS and CSA

28. What wire are knurled drive rolls most commonly used on?
Welding process that joins metals by heating them with an electric arc
Flux cored wires
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Puddle fluidity

29. In the GMAW process what does amperage control?
Penetration and burn - off rate of the electrode
Minutes of elapsed time continually run (out of 10 minutes)
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

30. List the factors that determine the mode of metal transfer
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
The negative side of a welding unit
To limit the short circuiting current so that spatter is reduced
Short- circuiting transfer - Globular transfer - Spray transfer

31. A pull type drive system is usually used on what type of material?
Welding process that joins metals by heating them with an electric arc
5.8 to 12.5 L/min
Aluminum wire
3

32. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
Insufficient current to melt the wire off cleanly
To prevent leakage - Carbon Dioxide (CO2)
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

33. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
15 feet (4.5 meters)
Higher 26 to 35 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
Constant voltage (CV)

34. Why is globular transfer generally avoided with GMAW?
Generally not as accurate
Spatter problems and poor weld appearance
Gas metal arc welding
To prevent drawing of liquid CO2 (Carbon Dioxide)

35. What is an advantage of pulsed arc transfer with GMAW?
AWS and CSA
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
If you dont know this check your phone
Controls the rate of flow of a shielding gas to the gun nozzle

36. What does voltage do in an electrical circuit?
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Voltage is the force that overcomes resistance to allow amperage flow
Controls the rate of flow of a shielding gas to the gun nozzle

37. What is the key advantage of short circuiting transfer?
Minimum distortion due to low heat input
Shielding the molten weld metal from atmospheric contamination
If you dont know this check your phone
Generally not as accurate

38. What is the preferred drive roll design for solid wires?
Gas metal arc welding
National Electrical Manufactures Association
V groove or U groove
...

39. List the basic equipment requirements for the GMAW process
Aluminum wire
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
If you dont know this check your phone
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

40. What output on the welding machine is used to rate the duty cycle?
Constant current (CC)
Minutes of elapsed time continually run (out of 10 minutes)
Guns
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

41. Why must CO2 cylinders be used in the vertical position?
Shielding the molten weld metal from atmospheric contamination
Welding process that joins metals by heating them with an electric arc
Speed of the feed motor and - starting / stopping electrode feed
To prevent drawing of liquid CO2 (Carbon Dioxide)

42. What is another term for electrode holders for GMAW?
85%
Guns
Cause flaking - which can clog the liner and contact tube
Wire feed speed - Voltage control

43. List 3 wire drive systems and give a short description of each
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
85%
To limit the short circuiting current so that spatter is reduced
5.8 to 12.5 L/min

44. Why is a line heater required when using GMAW?
Dry ice can form within the flow control openings and cause blockage of shielding gas
5.8 to 12.5 L/min
Speed of the feed motor and - starting / stopping electrode feed
Pressure - The rate of flow of a shielding gas

45. 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
Guns
Wire feeds smoothly (yet will slip should a problem occur in the gun)
20 to 200 times per second

46. With straight polarity where is 2/3 of the arc energy?
The negative side of a welding unit
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Welding process that joins metals by heating them with an electric arc
Reducing the gas source pressure to a constant working pressure

47. What does the wire feeder control?
Wire feed speed
The negative side of a welding unit
15 feet (4.5 meters)
Speed of the feed motor and - starting / stopping electrode feed

48. List several industries that would use GMAW
Flux cored wires
Pressure vessels and the piping industry
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
20 to 200 times per second

49. What controls amperage when using GMAW?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Duty cycle
If you dont know this check your phone
Wire feed speed

50. What is the maximum distance that hard wire can be successfully pushed?
1/4 inch to 1/2 inch
15 feet (4.5 meters)
Speed of the feed motor and - starting / stopping electrode feed
V groove or U groove