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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 are the 2 types of wire feeders available?
The resistace to electrical current flow increases with it. Causing the electrode to heat
...
12 to 22 arc volts
Constant- speed wire feeders and Voltage- sennsing wire feeders

2. What is the maximum distance that hard wire can be successfully pushed?
Penetration and burn - off rate of the electrode
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
To prevent leakage - Carbon Dioxide (CO2)
15 feet (4.5 meters)

3. How are GMAW guns rated?
By there current carrying capacity
3
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
1/4 inch to 1/2 inch

4. In the GMAW process what does voltage control?
Duty cycle
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
To prevent drawing of liquid CO2 (Carbon Dioxide)
Puddle fluidity

5. What 2 controls are found on a GMAW set- up?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Wire feed speed - Voltage control
20 to 200 times per second
Duty cycle

6. What would be an indication that the drive roll pressure is adjusted correctly?
Reducing the gas source pressure to a constant working pressure
Dry ice can form within the flow control openings and cause blockage of shielding gas
Wire feeds smoothly (yet will slip should a problem occur in the gun)
By there current carrying capacity

7. What is the main purpose of 'slope'?
To limit the short circuiting current so that spatter is reduced
Pressure - The rate of flow of a shielding gas
Higher 26 to 35 arc volts
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

8. List the three methods of metal transfer with GMAW
Speed of the feed motor and - starting / stopping electrode feed
Short- circuiting transfer - Globular transfer - Spray transfer
Constant current (CC)
...

9. What controls the wire speed on a voltage sensing wire feeder?
The Arc voltage
85%
The time rate of response for the current rise and fall
Motor driven generators - Transformer rectifiers - and Inverter designs

10. What is the required arc voltage used for short circuit transfer?
Pressure vessels and the piping industry
To limit the short circuiting current so that spatter is reduced
Shielding the molten weld metal from atmospheric contamination
12 to 22 arc volts

11. List 3 wire drive systems and give a short description of each
85%
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
12 to 22 arc volts

12. In the GMAW process what does amperage control?
Penetration and burn - off rate of the electrode
Dry ice can form within the flow control openings and cause blockage of shielding gas
National Electrical Manufactures Association
To prevent leakage - Carbon Dioxide (CO2)

13. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Duty cycle
85%
Short- circuiting transfer - Globular transfer - Spray transfer
DCEP (Direct Current Electrode Positive) Reverse Polarity

14. What controls amperage when using GMAW?
Penetration and burn - off rate of the electrode
Reducing the gas source pressure to a constant working pressure
Flux cored wires
Wire feed speed

15. Give a description of 'pinch effect'
DCEP (Direct Current Electrode Positive) Reverse Polarity
Constant- speed wire feeders and Voltage- sennsing wire feeders
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

16. What effect does increasing and decreasing the inductance have on the weld?
Motor driven generators - Transformer rectifiers - and Inverter designs
Shielding the molten weld metal from atmospheric contamination
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

17. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Aluminum wire
Higher 26 to 35 arc volts
Controls the rate of flow of a shielding gas to the gun nozzle
Short- circuiting transfer - Globular transfer - Spray transfer

18. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
AWS and CSA
To limit the short circuiting current so that spatter is reduced
Constant- speed wire feeders and Voltage- sennsing wire feeders
3

19. What is an advantage of pulsed arc transfer with GMAW?
85%
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)
Constant current (CC)

20. 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
Reducing the gas source pressure to a constant working pressure
5.8 to 12.5 L/min

21. List 3 forms compressed gases may be supplied for welding
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
By there current carrying capacity
12 to 22 arc volts
Shielding the molten weld metal from atmospheric contamination

22. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
85%
Constant current (CC)
National Electrical Manufactures Association
Minutes of elapsed time continually run (out of 10 minutes)

23. Why is a fiber washer required and what cylinder gas requires it?
To prevent leakage - Carbon Dioxide (CO2)
Wire feed speed - Voltage control
Speed of the feed motor and - starting / stopping electrode feed
Motor driven generators - Transformer rectifiers - and Inverter designs

24. What does inductance control?
Minutes of elapsed time continually run (out of 10 minutes)
The time rate of response for the current rise and fall
Generally not as accurate
These terms are quite restrictive and often technically incorrect

25. What type of power source is used with a constant speed wire feeder?
Constant voltage (CV)
Wire feed speed
15 feet (4.5 meters)
National Electrical Manufactures Association

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

27. What 2 organizations designate specifications for GMAW wires?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
AWS and CSA
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

28. What is the purpose of a regulator and what does it indicate on its gauges?
12 to 22 arc volts
Gives arc voltage values to the control system of the feeder
SMAW - GTAW
Reducing the gas source pressure to a constant working pressure

29. What is a typical flow rate of CO2 for short circuit transfer?
Short- circuiting transfer - Globular transfer - Spray transfer
5.8 to 12.5 L/min
1/4 inch to 1/2 inch
Voltage is the force that overcomes resistance to allow amperage flow

30. Why is the term GMAW preferred over MIG or MAG?
When the filler wire is in direct contract with the base metal
These terms are quite restrictive and often technically incorrect
AWS and CSA
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

31. With straight polarity where is 2/3 of the arc energy?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
The negative side of a welding unit
When the filler wire is in direct contract with the base metal
The time rate of response for the current rise and fall

32. Why is globular transfer generally avoided with GMAW?
Higher 26 to 35 arc volts
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Spatter problems and poor weld appearance
V groove or U groove

33. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
...
Aluminum wire
Duty cycle
SMAW - GTAW

34. What does the wire feeder control?
Speed of the feed motor and - starting / stopping electrode feed
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
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 prevent leakage - Carbon Dioxide (CO2)

35. Why must CO2 cylinders be used in the vertical position?
Penetration and burn - off rate of the electrode
To prevent drawing of liquid CO2 (Carbon Dioxide)
Cause flaking - which can clog the liner and contact tube
Voltage is the force that overcomes resistance to allow amperage flow

36. Regulators control_____________ flowmeters SHOW____________.
Pressure - The rate of flow of a shielding gas
20 to 200 times per second
Controls the rate of flow of a shielding gas to the gun nozzle
3

37. What is the effect of too much slope?
Aluminum wire
Insufficient current to melt the wire off cleanly
Spatter problems and poor weld appearance
Gas metal arc welding

38. What is another term for electrode holders for GMAW?
Voltage is the force that overcomes resistance to allow amperage flow
Guns
Pressure - The rate of flow of a shielding gas
Reducing the gas source pressure to a constant working pressure

39. Give a brief description of the GMAW process
Welding process that joins metals by heating them with an electric arc
The time rate of response for the current rise and fall
Pressure - The rate of flow of a shielding gas
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

40. How many times per second does short circuiting take place?
20 to 200 times per second
Minutes of elapsed time continually run (out of 10 minutes)
Welding process that joins metals by heating them with an electric arc
DCEP (Direct Current Electrode Positive) Reverse Polarity

41. What processes are constant current (CC) power sources designed to be used with?
(DCEP) Direct Current Electrode Positive or Reverse polarity
DCEP (Direct Current Electrode Positive) Reverse Polarity
SMAW - GTAW
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

42. What does the abbreviation NEMA stand for?
Constant- speed wire feeders and Voltage- sennsing wire feeders
National Electrical Manufactures Association
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

43. What is the purpose of the shielding gas used in GMAW?
5.8 to 12.5 L/min
12 to 22 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
Shielding the molten weld metal from atmospheric contamination

44. A pull type drive system is usually used on what type of material?
Dry ice can form within the flow control openings and cause blockage of shielding gas
Flux cored wires
The Arc voltage
Aluminum wire

45. What is the preferred drive roll design for solid wires?
V groove or U groove
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Insufficient current to melt the wire off cleanly
Flux cored wires

46. What is the key advantage of short circuiting transfer?
AWS and CSA
By there current carrying capacity
Minimum distortion due to low heat input
5.8 to 12.5 L/min

47. List several industries that would use GMAW
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Pressure vessels and the piping industry
Constant current (CC)

48. What output on the welding machine is used to rate the duty cycle?
AWS and CSA
If you dont know this check your phone
The resistace to electrical current flow increases with it. Causing the electrode to heat
Minutes of elapsed time continually run (out of 10 minutes)

49. List the factors that determine the mode of metal transfer
Aluminum wire
85%
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

50. Why is a line heater required when using GMAW?
The negative side of a welding unit
AWS and CSA
Penetration and burn - off rate of the electrode
Dry ice can form within the flow control openings and cause blockage of shielding gas