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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 3 forms compressed gases may be supplied for welding
The negative side of a welding unit
Aluminum wire
DCEP (Direct Current Electrode Positive) Reverse Polarity
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

2. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
(DCEP) Direct Current Electrode Positive or Reverse polarity
Flux cored wires
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
85%

3. Why is a line heater required when using GMAW?
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
...
Short- circuiting transfer - Globular transfer - Spray transfer
Dry ice can form within the flow control openings and cause blockage of shielding gas

4. What is the effect of too much slope?
Higher 26 to 35 arc volts
DCEP (Direct Current Electrode Positive) Reverse Polarity
Wire feed speed
Insufficient current to melt the wire off cleanly

5. What does the term GMAW identify?
Gas metal arc welding
When the filler wire is in direct contract with the base metal
Shielding the molten weld metal from atmospheric contamination
SMAW - GTAW

6. How are GMAW guns rated?
Shielding the molten weld metal from atmospheric contamination
By there current carrying capacity
If you dont know this check your phone
Motor driven generators - Transformer rectifiers - and Inverter designs

7. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
SMAW - GTAW
Cause flaking - which can clog the liner and contact tube
Pressure - The rate of flow of a shielding gas
5.8 to 12.5 L/min

8. What is a solenoid valve and what actuates it?
Generally not as accurate
Controls the rate of flow of a shielding gas to the gun nozzle
Spatter problems and poor weld appearance
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

9. A pull type drive system is usually used on what type of material?
...
DCEP (Direct Current Electrode Positive) Reverse Polarity
Aluminum wire
Speed of the feed motor and - starting / stopping electrode feed

10. What effect does increasing and decreasing the inductance have on the weld?
Higher 26 to 35 arc volts
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
Welding process that joins metals by heating them with an electric arc

11. What happens when the electrode extension is increased?
The resistace to electrical current flow increases with it. Causing the electrode to heat
To prevent drawing of liquid CO2 (Carbon Dioxide)
Aluminum wire
These terms are quite restrictive and often technically incorrect

12. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Pressure vessels and the piping industry
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
Gives arc voltage values to the control system of the feeder

13. Why is a fiber washer required and what cylinder gas requires it?
Cause flaking - which can clog the liner and contact tube
To limit the short circuiting current so that spatter is reduced
Generally not as accurate
To prevent leakage - Carbon Dioxide (CO2)

14. 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
To limit the short circuiting current so that spatter is reduced
Motor driven generators - Transformer rectifiers - and Inverter designs
Shielding the molten weld metal from atmospheric contamination

15. How many times per second does short circuiting take place?
85%
5.8 to 12.5 L/min
...
20 to 200 times per second

16. What output on the welding machine is used to rate the duty cycle?
Wire feed speed - Voltage control
1/4 inch to 1/2 inch
The resistace to electrical current flow increases with it. Causing the electrode to heat
Minutes of elapsed time continually run (out of 10 minutes)

17. 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
12 to 22 arc volts
The negative side of a welding unit

18. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
If you dont know this check your phone
When the filler wire is in direct contract with the base metal
Gives arc voltage values to the control system of the feeder
AWS and CSA

19. What power sources are used with the GMAW Process?
15 feet (4.5 meters)
Motor driven generators - Transformer rectifiers - and Inverter designs
Minimum distortion due to low heat input
The time rate of response for the current rise and fall

20. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
Puddle fluidity
These terms are quite restrictive and often technically incorrect
...
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

21. List several industries that would use GMAW
Voltage is the force that overcomes resistance to allow amperage flow
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Pressure vessels and the piping industry
To prevent leakage - Carbon Dioxide (CO2)

22. List the three methods of metal transfer with GMAW
Short- circuiting transfer - Globular transfer - Spray transfer
85%
To limit the short circuiting current so that spatter is reduced
Minutes of elapsed time continually run (out of 10 minutes)

23. What processes are constant current (CC) power sources designed to be used with?
Higher 26 to 35 arc volts
3
Motor driven generators - Transformer rectifiers - and Inverter designs
SMAW - GTAW

24. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
...
Higher 26 to 35 arc volts

25. What does the abbreviation NEMA stand for?
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
Gives arc voltage values to the control system of the feeder
Controls the rate of flow of a shielding gas to the gun nozzle
National Electrical Manufactures Association

26. A 10 minute cycle of welding time vs cooling time a given machine can handle.
1/4 inch to 1/2 inch
Reducing the gas source pressure to a constant working pressure
These terms are quite restrictive and often technically incorrect
Duty cycle

27. What does inductance control?
Controls the rate of flow of a shielding gas to the gun nozzle
Puddle fluidity
The time rate of response for the current rise and fall
20 to 200 times per second

28. List the factors that determine the mode of metal transfer
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
Generally not as accurate
Speed of the feed motor and - starting / stopping electrode feed

29. What would be an indication that the drive roll pressure is adjusted correctly?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
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
Wire feeds smoothly (yet will slip should a problem occur in the gun)

30. What does the wire feeder control?
Shielding the molten weld metal from atmospheric contamination
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
85%
Speed of the feed motor and - starting / stopping electrode feed

31. What is the recommended electrode stick- out for .035 solid wire?
Pressure vessels and the piping industry
1/4 inch to 1/2 inch
If you dont know this check your phone
Duty cycle

32. What is the key advantage of short circuiting transfer?
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
12 to 22 arc volts
Minimum distortion due to low heat input

33. In the GMAW process what does amperage control?
Constant voltage (CV)
To prevent drawing of liquid CO2 (Carbon Dioxide)
Flux cored wires
Penetration and burn - off rate of the electrode

34. What type of power source is used with a constant speed wire feeder?
These terms are quite restrictive and often technically incorrect
Wire feeds smoothly (yet will slip should a problem occur in the gun)
15 feet (4.5 meters)
Constant voltage (CV)

35. What 2 controls are found on a GMAW set- up?
SMAW - GTAW
Wire feed speed
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Wire feed speed - Voltage control

36. What controls the wire speed on a voltage sensing wire feeder?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Pressure vessels and the piping industry
The Arc voltage
V groove or U groove

37. What 2 organizations designate specifications for GMAW wires?
Reducing the gas source pressure to a constant working pressure
AWS and CSA
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Constant voltage (CV)

38. What is another term for electrode holders for GMAW?
Constant current (CC)
Guns
Motor driven generators - Transformer rectifiers - and Inverter designs
Dry ice can form within the flow control openings and cause blockage of shielding gas

39. What are the 2 types of wire feeders available?
Constant- speed wire feeders and Voltage- sennsing wire feeders
If you dont know this check your phone
Penetration and burn - off rate of the electrode
National Electrical Manufactures Association

40. Give a brief description of the GMAW process
Aluminum wire
Motor driven generators - Transformer rectifiers - and Inverter designs
Welding process that joins metals by heating them with an electric arc
Wire feed speed - Voltage control

41. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Constant- speed wire feeders and Voltage- sennsing wire feeders
If you dont know this check your phone
Generally not as accurate
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

42. What is the maximum distance that hard wire can be successfully pushed?
Minutes of elapsed time continually run (out of 10 minutes)
Higher 26 to 35 arc volts
15 feet (4.5 meters)
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

43. 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
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
Minutes of elapsed time continually run (out of 10 minutes)

44. What wire are knurled drive rolls most commonly used on?
Generally not as accurate
Short- circuiting transfer - Globular transfer - Spray transfer
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Flux cored wires

45. What is a typical flow rate of CO2 for short circuit transfer?
By there current carrying capacity
5.8 to 12.5 L/min
Gas metal arc welding
Puddle fluidity

46. List the basic equipment requirements for the GMAW process
...
Insufficient current to melt the wire off cleanly
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
If you dont know this check your phone

47. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
(DCEP) Direct Current Electrode Positive or Reverse polarity
Pressure vessels and the piping industry

48. What current and polarity is generally used with GMAW?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
DCEP (Direct Current Electrode Positive) Reverse Polarity
Gives arc voltage values to the control system of the feeder
Minutes of elapsed time continually run (out of 10 minutes)

49. What is the required arc voltage used for short circuit transfer?
Puddle fluidity
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Minutes of elapsed time continually run (out of 10 minutes)
12 to 22 arc volts

50. What is the purpose of the shielding gas used in GMAW?
The negative side of a welding unit
Constant voltage (CV)
Shielding the molten weld metal from atmospheric contamination
Pressure - The rate of flow of a shielding gas