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Gas Metal Arc Welding

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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 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
To prevent leakage - Carbon Dioxide (CO2)
To limit the short circuiting current so that spatter is reduced
Puddle fluidity

2. What processes are constant current (CC) power sources designed to be used with?
SMAW - GTAW
Controls the rate of flow of a shielding gas to the gun nozzle
Guns
Gas metal arc welding

3. List the three methods of metal transfer with GMAW
Insufficient current to melt the wire off cleanly
Constant voltage (CV)
Penetration and burn - off rate of the electrode
Short- circuiting transfer - Globular transfer - Spray transfer

4. In the GMAW process what does voltage control?
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
15 feet (4.5 meters)
Puddle fluidity
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

5. A pull type drive system is usually used on what type of material?
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
15 feet (4.5 meters)
Aluminum wire

6. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
When the filler wire is in direct contract with the base metal
These terms are quite restrictive and often technically incorrect
SMAW - GTAW
(DCEP) Direct Current Electrode Positive or Reverse polarity

7. What is the purpose of the shielding gas used in GMAW?
Insufficient current to melt the wire off cleanly
Shielding the molten weld metal from atmospheric contamination
Flux cored wires
Welding process that joins metals by heating them with an electric arc

8. What does the wire feeder control?
If you dont know this check your phone
Speed of the feed motor and - starting / stopping electrode feed
Guns
The negative side of a welding unit

9. What are the 2 types of wire feeders available?
Gives arc voltage values to the control system of the feeder
If you dont know this check your phone
To prevent drawing of liquid CO2 (Carbon Dioxide)
Constant- speed wire feeders and Voltage- sennsing wire feeders

10. Regulators control_____________ flowmeters SHOW____________.
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Pressure - The rate of flow of a shielding gas
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Short- circuiting transfer - Globular transfer - Spray transfer

11. 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
If you dont know this check your phone
Wire feed speed - Voltage control
National Electrical Manufactures Association

12. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
...
Constant current (CC)
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
(DCEP) Direct Current Electrode Positive or Reverse polarity

13. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
Voltage is the force that overcomes resistance to allow amperage flow
The resistace to electrical current flow increases with it. Causing the electrode to heat
5.8 to 12.5 L/min
If you dont know this check your phone

14. What power sources are used with the GMAW Process?
Higher 26 to 35 arc volts
The negative side of a welding unit
Short- circuiting transfer - Globular transfer - Spray transfer
Motor driven generators - Transformer rectifiers - and Inverter designs

15. What is a solenoid valve and what actuates it?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Wire feeds smoothly (yet will slip should a problem occur in the gun)
(DCEP) Direct Current Electrode Positive or Reverse polarity
Constant current (CC)

16. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
The resistace to electrical current flow increases with it. Causing the electrode to heat
If you dont know this check your phone
If you dont know this check your phone
Higher 26 to 35 arc volts

17. What controls amperage when using GMAW?
Wire feed speed
To prevent leakage - Carbon Dioxide (CO2)
The resistace to electrical current flow increases with it. Causing the electrode to heat
Penetration and burn - off rate of the electrode

18. What is the preferred drive roll design for solid wires?
V groove or U groove
Cause flaking - which can clog the liner and contact tube
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
The resistace to electrical current flow increases with it. Causing the electrode to heat

19. What does the term GMAW identify?
Gas metal arc welding
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
The resistace to electrical current flow increases with it. Causing the electrode to heat
Voltage is the force that overcomes resistance to allow amperage flow

20. Give a description of 'pinch effect'
Short- circuiting transfer - Globular transfer - Spray transfer
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
The time rate of response for the current rise and fall

21. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
12 to 22 arc volts
Reducing the gas source pressure to a constant working pressure
SMAW - GTAW
Gives arc voltage values to the control system of the feeder

22. 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
National Electrical Manufactures Association
The negative side of a welding unit
5.8 to 12.5 L/min

23. What 2 controls are found on a GMAW set- up?
Spatter problems and poor weld appearance
Guns
Wire feed speed - Voltage control
To prevent leakage - Carbon Dioxide (CO2)

24. What output on the welding machine is used to rate the duty cycle?
Minutes of elapsed time continually run (out of 10 minutes)
When the filler wire is in direct contract with the base metal
Controls the rate of flow of a shielding gas to the gun nozzle
Dry ice can form within the flow control openings and cause blockage of shielding gas

25. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Generally not as accurate
The Arc voltage
Controls the rate of flow of a shielding gas to the gun nozzle
(DCEP) Direct Current Electrode Positive or Reverse polarity

26. What type of power source is commonly used with a voltage sensing wire feeder?
When the filler wire is in direct contract with the base metal
Insufficient current to melt the wire off cleanly
Constant current (CC)
Aluminum wire

27. Why is globular transfer generally avoided with GMAW?
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
Spatter problems and poor weld appearance
Pressure vessels and the piping industry
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

28. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Insufficient current to melt the wire off cleanly
The time rate of response for the current rise and fall
Flux cored wires
Duty cycle

29. What current and polarity is generally used with GMAW?
To limit the short circuiting current so that spatter is reduced
Dry ice can form within the flow control openings and cause blockage of shielding gas
Constant- speed wire feeders and Voltage- sennsing wire feeders
DCEP (Direct Current Electrode Positive) Reverse Polarity

30. How are GMAW guns rated?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
By there current carrying capacity
The Arc voltage

31. In the GMAW process what does amperage control?
Penetration and burn - off rate of the electrode
1/4 inch to 1/2 inch
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
National Electrical Manufactures Association

32. Why is a line heater required when using GMAW?
Dry ice can form within the flow control openings and cause blockage of shielding gas
Aluminum wire
Controls the rate of flow of a shielding gas to the gun nozzle
Pressure vessels and the piping industry

33. What is the effect of too much slope?
To prevent leakage - Carbon Dioxide (CO2)
15 feet (4.5 meters)
Insufficient current to melt the wire off cleanly
Dry ice can form within the flow control openings and cause blockage of shielding gas

34. List the factors that determine the mode of metal transfer
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
When the filler wire is in direct contract with the base metal
If you dont know this check your phone
3

35. Why must CO2 cylinders be used in the vertical position?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
The Arc voltage
To prevent drawing of liquid CO2 (Carbon Dioxide)
Gives arc voltage values to the control system of the feeder

36. What does the abbreviation NEMA stand for?
20 to 200 times per second
...
National Electrical Manufactures Association
Minutes of elapsed time continually run (out of 10 minutes)

37. What happens when the electrode extension is increased?
15 feet (4.5 meters)
The negative side of a welding unit
The resistace to electrical current flow increases with it. Causing the electrode to heat
Higher 26 to 35 arc volts

38. Why is a fiber washer required and what cylinder gas requires it?
To prevent leakage - Carbon Dioxide (CO2)
85%
Flux cored wires
Controls the rate of flow of a shielding gas to the gun nozzle

39. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Gas metal arc welding
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
3

40. What wire are knurled drive rolls most commonly used on?
Dry ice can form within the flow control openings and cause blockage of shielding gas
Gives arc voltage values to the control system of the feeder
Flux cored wires
85%

41. What is a typical flow rate of CO2 for short circuit transfer?
5.8 to 12.5 L/min
Higher 26 to 35 arc volts
Pressure vessels and the piping industry
The negative side of a welding unit

42. What is the maximum distance that hard wire can be successfully pushed?
Minutes of elapsed time continually run (out of 10 minutes)
Wire feed speed - Voltage control
Pressure vessels and the piping industry
15 feet (4.5 meters)

43. What does inductance control?
85%
Higher 26 to 35 arc volts
The resistace to electrical current flow increases with it. Causing the electrode to heat
The time rate of response for the current rise and fall

44. What effect does increasing and decreasing the inductance have on the weld?
These terms are quite restrictive and often technically incorrect
Puddle fluidity
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 - The rate of flow of a shielding gas

45. Give a brief description of the GMAW process
3
Insufficient current to melt the wire off cleanly
Welding process that joins metals by heating them with an electric arc
Minimum distortion due to low heat input

46. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
Generally not as accurate
85%
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- speed wire feeders and Voltage- sennsing wire feeders

47. What is the key advantage of short circuiting transfer?
Minimum distortion due to low heat input
Controls the rate of flow of a shielding gas to the gun nozzle
Motor driven generators - Transformer rectifiers - and Inverter designs
Aluminum wire

48. What is the recommended electrode stick- out for .035 solid wire?
12 to 22 arc volts
Higher 26 to 35 arc volts
1/4 inch to 1/2 inch
(DCEP) Direct Current Electrode Positive or Reverse polarity

49. How many times per second does short circuiting take place?
12 to 22 arc volts
20 to 200 times per second
15 feet (4.5 meters)
Dry ice can form within the flow control openings and cause blockage of shielding gas

50. Why is the term GMAW preferred over MIG or MAG?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
12 to 22 arc volts
These terms are quite restrictive and often technically incorrect
3

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