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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 does a flowmeter do and what does it measure?
Generally not as accurate
Controls the rate of flow of a shielding gas to the gun nozzle
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Gas metal arc welding

2. List several industries that would use GMAW
Aluminum wire
Pressure vessels and the piping industry
3
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

3. What is another term for electrode holders for GMAW?
Wire feed speed
3
Guns
The Arc voltage

4. List 3 wire drive systems and give a short description of each
Pressure vessels and the piping industry
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
Speed of the feed motor and - starting / stopping electrode feed
Minimum distortion due to low heat input

5. What does voltage do in an electrical circuit?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
National Electrical Manufactures Association
Voltage is the force that overcomes resistance to allow amperage flow

6. Why is a line heater required when using GMAW?
(DCEP) Direct Current Electrode Positive or Reverse polarity
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Dry ice can form within the flow control openings and cause blockage of shielding gas
To limit the short circuiting current so that spatter is reduced

7. List the factors that determine the mode of metal transfer
20 to 200 times per second
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
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

8. Why is globular transfer generally avoided with GMAW?
Dry ice can form within the flow control openings and cause blockage of shielding gas
Spatter problems and poor weld appearance
Controls the rate of flow of a shielding gas to the gun nozzle
Constant current (CC)

9. How many times per second does short circuiting take place?
20 to 200 times per second
15 feet (4.5 meters)
Voltage is the force that overcomes resistance to allow amperage flow
Constant- speed wire feeders and Voltage- sennsing wire feeders

10. What is the maximum distance that hard wire can be successfully pushed?
Constant voltage (CV)
3
15 feet (4.5 meters)
Minutes of elapsed time continually run (out of 10 minutes)

11. What is the main purpose of 'slope'?
To limit the short circuiting current so that spatter is reduced
To prevent leakage - Carbon Dioxide (CO2)
Minutes of elapsed time continually run (out of 10 minutes)
To prevent drawing of liquid CO2 (Carbon Dioxide)

12. List the basic equipment requirements for the GMAW process
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Motor driven generators - Transformer rectifiers - and Inverter designs
Insufficient current to melt the wire off cleanly
Cause flaking - which can clog the liner and contact tube

13. What is the preferred drive roll design for solid wires?
Speed of the feed motor and - starting / stopping electrode feed
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Wire feeds smoothly (yet will slip should a problem occur in the gun)
V groove or U groove

14. What is the recommended electrode stick- out for .035 solid wire?
15 feet (4.5 meters)
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Speed of the feed motor and - starting / stopping electrode feed
1/4 inch to 1/2 inch

15. What is the effect of too much slope?
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
Insufficient current to melt the wire off cleanly
The Arc voltage

16. Why is the term GMAW preferred over MIG or MAG?
Cause flaking - which can clog the liner and contact tube
By there current carrying capacity
These terms are quite restrictive and often technically incorrect
V groove or U groove

17. What does the abbreviation NEMA stand for?
If you dont know this check your phone
3
Penetration and burn - off rate of the electrode
National Electrical Manufactures Association

18. What is the key advantage of short circuiting transfer?
Motor driven generators - Transformer rectifiers - and Inverter designs
Minimum distortion due to low heat input
1/4 inch to 1/2 inch
Pressure - The rate of flow of a shielding gas

19. What type of power source is used with a constant speed wire feeder?
If you dont know this check your phone
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Controls the rate of flow of a shielding gas to the gun nozzle
Constant voltage (CV)

20. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
Duty cycle
5.8 to 12.5 L/min
Speed of the feed motor and - starting / stopping electrode feed
...

21. What is a typical flow rate of CO2 for short circuit transfer?
Penetration and burn - off rate of the electrode
Pressure - The rate of flow of a shielding gas
When the filler wire is in direct contract with the base metal
5.8 to 12.5 L/min

22. What effect does increasing and decreasing the inductance have on the weld?
The Arc voltage
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Minutes of elapsed time continually run (out of 10 minutes)
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

23. What 2 controls are found on a GMAW set- up?
To prevent leakage - Carbon Dioxide (CO2)
Constant current (CC)
Motor driven generators - Transformer rectifiers - and Inverter designs
Wire feed speed - Voltage control

24. What 2 organizations designate specifications for GMAW wires?
AWS and CSA
Shielding the molten weld metal from atmospheric contamination
Gas metal arc welding
To prevent drawing of liquid CO2 (Carbon Dioxide)

25. Draw a typical volt amp curve for a machine that is designed for GMAW
If you dont know this check your phone
AWS and CSA
V groove or U groove
Wire feeds smoothly (yet will slip should a problem occur in the gun)

26. What controls the wire speed on a voltage sensing wire feeder?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
To prevent leakage - Carbon Dioxide (CO2)
20 to 200 times per second
The Arc voltage

27. What is the purpose of the shielding gas used in GMAW?
Shielding the molten weld metal from atmospheric contamination
SMAW - GTAW
Cause flaking - which can clog the liner and contact tube
3

28. What processes are constant current (CC) power sources designed to be used with?
AWS and CSA
Wire feed speed
12 to 22 arc volts
SMAW - GTAW

29. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Penetration and burn - off rate of the electrode
Constant current (CC)
Higher 26 to 35 arc volts
Minutes of elapsed time continually run (out of 10 minutes)

30. Why is a fiber washer required and what cylinder gas requires it?
Minimum distortion due to low heat input
To prevent leakage - Carbon Dioxide (CO2)
If you dont know this check your phone
...

31. A 10 minute cycle of welding time vs cooling time a given machine can handle.
The negative side of a welding unit
Duty cycle
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Constant- speed wire feeders and Voltage- sennsing wire feeders

32. What type of power source is commonly used with a voltage sensing wire feeder?
The negative side of a welding unit
3
Constant current (CC)
Cause flaking - which can clog the liner and contact tube

33. List 3 forms compressed gases may be supplied for welding
Welding process that joins metals by heating them with an electric arc
If you dont know this check your phone
Generally not as accurate
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

34. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
Motor driven generators - Transformer rectifiers - and Inverter designs
The resistace to electrical current flow increases with it. Causing the electrode to heat
If you dont know this check your phone
Wire feed speed - Voltage control

35. What is a solenoid valve and what actuates it?
Gives arc voltage values to the control system of the feeder
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
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
Motor driven generators - Transformer rectifiers - and Inverter designs

36. With straight polarity where is 2/3 of the arc energy?
The negative side of a welding unit
The Arc voltage
(DCEP) Direct Current Electrode Positive or Reverse polarity
Minutes of elapsed time continually run (out of 10 minutes)

37. Why must CO2 cylinders be used in the vertical position?
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
85%
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
To prevent drawing of liquid CO2 (Carbon Dioxide)

38. In the GMAW process what does voltage control?
By there current carrying capacity
Dry ice can form within the flow control openings and cause blockage of shielding gas
Puddle fluidity
Wire feeds smoothly (yet will slip should a problem occur in the gun)

39. What wire are knurled drive rolls most commonly used on?
Puddle fluidity
To prevent drawing of liquid CO2 (Carbon Dioxide)
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Flux cored wires

40. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
85%
Gives arc voltage values to the control system of the feeder
DCEP (Direct Current Electrode Positive) Reverse Polarity
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

41. What does inductance control?
Motor driven generators - Transformer rectifiers - and Inverter designs
(DCEP) Direct Current Electrode Positive or Reverse polarity
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
The time rate of response for the current rise and fall

42. A pull type drive system is usually used on what type of material?
85%
Flux cored wires
When the filler wire is in direct contract with the base metal
Aluminum wire

43. List the three methods of metal transfer with GMAW
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
Short- circuiting transfer - Globular transfer - Spray transfer
Motor driven generators - Transformer rectifiers - and Inverter designs

44. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
V groove or U groove
Wire feed speed - Voltage control
Cause flaking - which can clog the liner and contact tube

45. Give a description of 'pinch effect'
5.8 to 12.5 L/min
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
Gas metal arc welding

46. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
To prevent drawing of liquid CO2 (Carbon Dioxide)
3
When the filler wire is in direct contract with the base metal
Gas metal arc welding

47. What current and polarity is generally used with GMAW?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Pressure - The rate of flow of a shielding gas
Aluminum wire
12 to 22 arc volts

48. How are GMAW guns rated?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Gives arc voltage values to the control system of the feeder
AWS and CSA
By there current carrying capacity

49. What are the 2 types of wire feeders available?
Flux cored wires
Constant- speed wire feeders and Voltage- sennsing wire feeders
Controls the rate of flow of a shielding gas to the gun nozzle
Insufficient current to melt the wire off cleanly

50. In the GMAW process what does amperage control?
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Controls the rate of flow of a shielding gas to the gun nozzle
Penetration and burn - off rate of the electrode
Wire feed speed