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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.
Don't refresh. All questions and answers are randomly picked and ordered every time you load a test.

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. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Higher 26 to 35 arc volts
To limit the short circuiting current so that spatter is reduced
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Flux cored wires

2. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Minimum distortion due to low heat input
Guns
Gives arc voltage values to the control system of the feeder
The negative side of a welding unit

3. Why must CO2 cylinders be used in the vertical position?
Wire feed speed - Voltage control
To prevent leakage - Carbon Dioxide (CO2)
To prevent drawing of liquid CO2 (Carbon Dioxide)
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

4. Why is the term GMAW preferred over MIG or MAG?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
...
These terms are quite restrictive and often technically incorrect
Insufficient current to melt the wire off cleanly

5. List 3 forms compressed gases may be supplied for welding
Constant current (CC)
When the filler wire is in direct contract with the base metal
Cause flaking - which can clog the liner and contact tube
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

6. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
Shielding the molten weld metal from atmospheric contamination
The resistace to electrical current flow increases with it. Causing the electrode to heat
...
Motor driven generators - Transformer rectifiers - and Inverter designs

7. What does a flowmeter do and what does it measure?
Spatter problems and poor weld appearance
Controls the rate of flow of a shielding gas to the gun nozzle
12 to 22 arc volts
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8. What wire are knurled drive rolls most commonly used on?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Flux cored wires
Guns
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

9. List 3 wire drive systems and give a short description of each
Wire feed speed
Spatter problems and poor weld appearance
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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

10. What is the purpose of a regulator and what does it indicate on its gauges?
The Arc voltage
To prevent drawing of liquid CO2 (Carbon Dioxide)
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Reducing the gas source pressure to a constant working pressure

11. How are GMAW guns rated?
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Wire feeds smoothly (yet will slip should a problem occur in the gun)
By there current carrying capacity
...

12. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Duty cycle
Minimum distortion due to low heat input
SMAW - GTAW

13. List the three methods of metal transfer with GMAW
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
When the filler wire is in direct contract with the base metal
Welding process that joins metals by heating them with an electric arc
Short- circuiting transfer - Globular transfer - Spray transfer

14. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
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These terms are quite restrictive and often technically incorrect
Constant- speed wire feeders and Voltage- sennsing wire feeders
1/4 inch to 1/2 inch

15. What 2 organizations designate specifications for GMAW wires?
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AWS and CSA
National Electrical Manufactures Association
1/4 inch to 1/2 inch

16. Give a description of 'pinch effect'
Aluminum wire
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
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

17. What 2 controls are found on a GMAW set- up?
15 feet (4.5 meters)
Wire feed speed - Voltage control
Controls the rate of flow of a shielding gas to the gun nozzle
12 to 22 arc volts

18. What happens when the electrode extension is increased?
The time rate of response for the current rise and fall
Gives arc voltage values to the control system of the feeder
85%
The resistace to electrical current flow increases with it. Causing the electrode to heat

19. Why is globular transfer generally avoided with GMAW?
To limit the short circuiting current so that spatter is reduced
1/4 inch to 1/2 inch
Spatter problems and poor weld appearance
AWS and CSA

20. 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
Wire feed speed
National Electrical Manufactures Association
Constant voltage (CV)

21. What is the preferred drive roll design for solid wires?
V groove or U groove
The time rate of response for the current rise and fall
Speed of the feed motor and - starting / stopping electrode feed
Controls the rate of flow of a shielding gas to the gun nozzle

22. What power sources are used with the GMAW Process?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Speed of the feed motor and - starting / stopping electrode feed
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Motor driven generators - Transformer rectifiers - and Inverter designs

23. What is the main purpose of 'slope'?
...
Motor driven generators - Transformer rectifiers - and Inverter designs
20 to 200 times per second
To limit the short circuiting current so that spatter is reduced

24. What processes are constant current (CC) power sources designed to be used with?
SMAW - GTAW
Pressure vessels and the piping industry
Constant voltage (CV)
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

25. List the factors that determine the mode of metal transfer
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Welding process that joins metals by heating them with an electric arc
Minimum distortion due to low heat input
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

26. When is the metal transferred with short circuit transfer?
To limit the short circuiting current so that spatter is reduced
When the filler wire is in direct contract with the base metal
12 to 22 arc volts
The time rate of response for the current rise and fall

27. How many times per second does short circuiting take place?
20 to 200 times per second
(DCEP) Direct Current Electrode Positive or Reverse polarity
5.8 to 12.5 L/min
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. In the GMAW process what does voltage control?
Puddle fluidity
Speed of the feed motor and - starting / stopping electrode feed
Guns
The time rate of response for the current rise and fall

29. What is an advantage of pulsed arc transfer with GMAW?
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
When the filler wire is in direct contract with the base metal
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

30. With straight polarity where is 2/3 of the arc energy?
The negative side of a welding unit
Cause flaking - which can clog the liner and contact tube
Gas metal arc welding
Guns

31. What is a solenoid valve and what actuates it?
Duty cycle
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Welding process that joins metals by heating them with an electric arc
Controls the rate of flow of a shielding gas to the gun nozzle

32. What output on the welding machine is used to rate the duty cycle?
DCEP (Direct Current Electrode Positive) Reverse Polarity
When the filler wire is in direct contract with the base metal
Minutes of elapsed time continually run (out of 10 minutes)
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

33. What does the wire feeder control?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
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
Speed of the feed motor and - starting / stopping electrode feed

34. A pull type drive system is usually used on what type of material?
Motor driven generators - Transformer rectifiers - and Inverter designs
Aluminum wire
Constant current (CC)
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

35. Why is a line heater required when using GMAW?
Dry ice can form within the flow control openings and cause blockage of shielding gas
15 feet (4.5 meters)
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Short- circuiting transfer - Globular transfer - Spray transfer

36. What is another term for electrode holders for GMAW?
Guns
Pressure vessels and the piping industry
Wire feeds smoothly (yet will slip should a problem occur in the gun)
5.8 to 12.5 L/min

37. In the GMAW process what does amperage control?
Penetration and burn - off rate of the electrode
Flux cored wires
Minutes of elapsed time continually run (out of 10 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

38. What are the 2 types of wire feeders available?
To prevent drawing of liquid CO2 (Carbon Dioxide)
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Constant- speed wire feeders and Voltage- sennsing wire feeders
To limit the short circuiting current so that spatter is reduced

39. What is the recommended electrode stick- out for .035 solid wire?
1/4 inch to 1/2 inch
Gas metal arc welding
Generally not as accurate
When the filler wire is in direct contract with the base metal

40. List several industries that would use GMAW
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Pressure vessels and the piping industry
Reducing the gas source pressure to a constant working pressure
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

41. Give a brief description of the GMAW process
Welding process that joins metals by heating them with an electric arc
DCEP (Direct Current Electrode Positive) Reverse Polarity
Gives arc voltage values to the control system of the feeder
Aluminum wire

42. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Insufficient current to melt the wire off cleanly
Cause flaking - which can clog the liner and contact tube
Dry ice can form within the flow control openings and cause blockage of shielding gas
To prevent leakage - Carbon Dioxide (CO2)

43. List the basic equipment requirements for the GMAW process
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
12 to 22 arc volts
Minutes of elapsed time continually run (out of 10 minutes)
To prevent leakage - Carbon Dioxide (CO2)

44. What controls amperage when using GMAW?
...
Cause flaking - which can clog the liner and contact tube
Wire feed speed
These terms are quite restrictive and often technically incorrect

45. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
Motor driven generators - Transformer rectifiers - and Inverter designs
Shielding the molten weld metal from atmospheric contamination
(DCEP) Direct Current Electrode Positive or Reverse polarity
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

46. What is the key advantage of short circuiting transfer?
85%
Minimum distortion due to low heat input
15 feet (4.5 meters)
The negative side of a welding unit

47. Why is a fiber washer required and what cylinder gas requires it?
AWS and CSA
To prevent leakage - Carbon Dioxide (CO2)
Minimum distortion due to low heat input
Motor driven generators - Transformer rectifiers - and Inverter designs

48. What does inductance control?
Insufficient current to melt the wire off cleanly
The time rate of response for the current rise and fall
20 to 200 times per second
Puddle fluidity

49. What is the purpose of the shielding gas used in GMAW?
Shielding the molten weld metal from atmospheric contamination
Puddle fluidity
Voltage is the force that overcomes resistance to allow amperage flow
AWS and CSA

50. What is the effect of too much slope?
Insufficient current to melt the wire off cleanly
Puddle fluidity
Aluminum wire
(DCEP) Direct Current Electrode Positive or Reverse polarity