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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 maximum distance that hard wire can be successfully pushed?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
15 feet (4.5 meters)
Insufficient current to melt the wire off cleanly
Shielding the molten weld metal from atmospheric contamination

2. What does the term GMAW identify?
Gas metal arc welding
Controls the rate of flow of a shielding gas to the gun nozzle
Aluminum wire
DCEP (Direct Current Electrode Positive) Reverse Polarity

3. List the three methods of metal transfer with GMAW
Pressure vessels and the piping industry
Higher 26 to 35 arc volts
20 to 200 times per second
Short- circuiting transfer - Globular transfer - Spray transfer

4. What is the purpose of a regulator and what does it indicate on its gauges?
National Electrical Manufactures Association
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Reducing the gas source pressure to a constant working pressure
(DCEP) Direct Current Electrode Positive or Reverse polarity

5. What happens when the electrode extension is increased?
Controls the rate of flow of a shielding gas to the gun nozzle
Guns
The resistace to electrical current flow increases with it. Causing the electrode to heat
Flux cored wires

6. Why must CO2 cylinders be used in the vertical position?
To prevent drawing of liquid CO2 (Carbon Dioxide)
Penetration and burn - off rate of the electrode
Wire feed speed
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

7. What output on the welding machine is used to rate the duty cycle?
Insufficient current to melt the wire off cleanly
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Wire feed speed
Minutes of elapsed time continually run (out of 10 minutes)

8. What power sources are used with the GMAW Process?
Constant current (CC)
Motor driven generators - Transformer rectifiers - and Inverter designs
Penetration and burn - off rate of the electrode
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9. What wire are knurled drive rolls most commonly used on?
Flux cored wires
20 to 200 times per second
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

10. What is the main purpose of 'slope'?
To limit the short circuiting current so that spatter is reduced
12 to 22 arc volts
Flux cored wires
Controls the rate of flow of a shielding gas to the gun nozzle

11. Why is a line heater required when using GMAW?
12 to 22 arc volts
Flux cored wires
Dry ice can form within the flow control openings and cause blockage of shielding gas
(DCEP) Direct Current Electrode Positive or Reverse polarity

12. What is the effect of too much slope?
Wire feed speed - Voltage control
Constant voltage (CV)
Penetration and burn - off rate of the electrode
Insufficient current to melt the wire off cleanly

13. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
85%
Shielding the molten weld metal from atmospheric contamination
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When the filler wire is in direct contract with the base metal

14. What 2 organizations designate specifications for GMAW wires?
Cause flaking - which can clog the liner and contact tube
Pressure vessels and the piping industry
Duty cycle
AWS and CSA

15. What current and polarity is generally used with GMAW?
The resistace to electrical current flow increases with it. Causing the electrode to heat
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
DCEP (Direct Current Electrode Positive) Reverse Polarity
Controls the rate of flow of a shielding gas to the gun nozzle

16. With straight polarity where is 2/3 of the arc energy?
The negative side of a welding unit
5.8 to 12.5 L/min
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Reducing the gas source pressure to a constant working pressure

17. List 3 forms compressed gases may be supplied for welding
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Short- circuiting transfer - Globular transfer - Spray transfer
The resistace to electrical current flow increases with it. Causing the electrode to heat
20 to 200 times per second

18. List the basic equipment requirements for the GMAW process
Spatter problems and poor weld appearance
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
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Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

19. A pull type drive system is usually used on what type of material?
National Electrical Manufactures Association
15 feet (4.5 meters)
Aluminum wire
Generally not as accurate

20. Give a brief description of the GMAW process
Welding process that joins metals by heating them with an electric arc
Cause flaking - which can clog the liner and contact tube
Wire feed speed
Wire feeds smoothly (yet will slip should a problem occur in the gun)

21. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
Wire feed speed
Duty cycle
(DCEP) Direct Current Electrode Positive or Reverse polarity
Spatter problems and poor weld appearance

22. What type of power source is used with a constant speed wire feeder?
20 to 200 times per second
Constant voltage (CV)
Pressure vessels and the piping industry
Gives arc voltage values to the control system of the feeder

23. 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
Constant voltage (CV)
Dry ice can form within the flow control openings and cause blockage of shielding gas
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

24. Regulators control_____________ flowmeters SHOW____________.
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Insufficient current to melt the wire off cleanly
National Electrical Manufactures Association
Pressure - The rate of flow of a shielding gas

25. What processes are constant current (CC) power sources designed to be used with?
SMAW - GTAW
Wire feeds smoothly (yet will slip should a problem occur in the gun)
3
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26. What does inductance control?
The time rate of response for the current rise and fall
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Spatter problems and poor weld appearance
Higher 26 to 35 arc volts

27. 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
Minutes of elapsed time continually run (out of 10 minutes)
20 to 200 times per second
To limit the short circuiting current so that spatter is reduced

28. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Constant voltage (CV)
Generally not as accurate
5.8 to 12.5 L/min
...

29. What is the purpose of the shielding gas used in GMAW?
Motor driven generators - Transformer rectifiers - and Inverter designs
Reducing the gas source pressure to a constant working pressure
Shielding the molten weld metal from atmospheric contamination
SMAW - GTAW

30. How are GMAW guns rated?
By there current carrying capacity
Voltage is the force that overcomes resistance to allow amperage flow
Reducing the gas source pressure to a constant working pressure
(DCEP) Direct Current Electrode Positive or Reverse polarity

31. What controls amperage when using GMAW?
Gives arc voltage values to the control system of the feeder
Wire feed speed
Generally not as accurate
SMAW - GTAW

32. What is an advantage of pulsed arc transfer with GMAW?
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
National Electrical Manufactures Association
Generally not as accurate

33. Draw a typical volt amp curve for a machine that is designed for GMAW
Wire feeds smoothly (yet will slip should a problem occur in the gun)
National Electrical Manufactures Association
If you dont know this check your phone
Wire feed speed - Voltage control

34. What controls the wire speed on a voltage sensing wire feeder?
The Arc voltage
Minutes of elapsed time continually run (out of 10 minutes)
Welding process that joins metals by heating them with an electric arc
To prevent leakage - Carbon Dioxide (CO2)

35. In the GMAW process what does amperage control?
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
Penetration and burn - off rate of the electrode
Short- circuiting transfer - Globular transfer - Spray transfer

36. What is the key advantage of short circuiting transfer?
12 to 22 arc volts
Pressure vessels and the piping industry
Minimum distortion due to low heat input
Insufficient current to melt the wire off cleanly

37. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
3
Constant voltage (CV)
...
Constant current (CC)

38. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
SMAW - GTAW
Pressure vessels and the piping industry
Constant voltage (CV)
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39. What is a solenoid valve and what actuates it?
Aluminum wire
If you dont know this check your phone
National Electrical Manufactures Association
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

40. 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
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Constant current (CC)
Minutes of elapsed time continually run (out of 10 minutes)

41. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Gives arc voltage values to the control system of the feeder
Flux cored wires
Generally not as accurate
To prevent leakage - Carbon Dioxide (CO2)

42. What does voltage do in an electrical circuit?
5.8 to 12.5 L/min
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Welding process that joins metals by heating them with an electric arc
Voltage is the force that overcomes resistance to allow amperage flow

43. Give a description of 'pinch effect'
To prevent leakage - Carbon Dioxide (CO2)
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
The negative side of a welding unit
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

44. In the GMAW process what does voltage control?
When the filler wire is in direct contract with the base metal
Puddle fluidity
1/4 inch to 1/2 inch
Minimum distortion due to low heat input

45. What is a typical flow rate of CO2 for short circuit transfer?
Shielding the molten weld metal from atmospheric contamination
The time rate of response for the current rise and fall
Minutes of elapsed time continually run (out of 10 minutes)
5.8 to 12.5 L/min

46. Why is the term GMAW preferred over MIG or MAG?
These terms are quite restrictive and often technically incorrect
SMAW - GTAW
National Electrical Manufactures Association
When the filler wire is in direct contract with the base metal

47. Why is globular transfer generally avoided with GMAW?
Constant current (CC)
DCEP (Direct Current Electrode Positive) Reverse Polarity
Pressure vessels and the piping industry
Spatter problems and poor weld appearance

48. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
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
3
...
These terms are quite restrictive and often technically incorrect

49. What 2 controls are found on a GMAW set- up?
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
Penetration and burn - off rate of the electrode
Pressure - The rate of flow of a shielding gas

50. 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
Constant voltage (CV)
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)