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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 purpose of the pick- up lead on a voltage sensing wire feeder?
Duty cycle
Gives arc voltage values to the control system of the feeder
Constant current (CC)
...

2. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Duty cycle
Higher 26 to 35 arc volts
When the filler wire is in direct contract with the base metal

3. What would be an indication that the drive roll pressure is adjusted correctly?
Voltage is the force that overcomes resistance to allow amperage flow
3
Wire feeds smoothly (yet will slip should a problem occur in the gun)
12 to 22 arc volts

4. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
3
Spatter problems and poor weld appearance
Constant voltage (CV)
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

5. What are the 2 types of wire feeders available?
Constant- speed wire feeders and Voltage- sennsing wire feeders
Motor driven generators - Transformer rectifiers - and Inverter designs
To prevent drawing of liquid CO2 (Carbon Dioxide)
20 to 200 times per second

6. What is another term for electrode holders for GMAW?
Guns
15 feet (4.5 meters)
Duty cycle
Puddle fluidity

7. List the basic equipment requirements for the GMAW process
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
V groove or U groove
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

8. What current and polarity is generally used with GMAW?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Generally not as accurate
The Arc voltage
Gives arc voltage values to the control system of the feeder

9. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Cause flaking - which can clog the liner and contact tube
To prevent leakage - Carbon Dioxide (CO2)
If you dont know this check your phone
Higher 26 to 35 arc volts

10. With straight polarity where is 2/3 of the arc energy?
The negative side of a welding unit
DCEP (Direct Current Electrode Positive) 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
SMAW - GTAW

11. What is the preferred drive roll design for solid wires?
Generally not as accurate
V groove or U groove
The time rate of response for the current rise and fall
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. Why is a fiber washer required and what cylinder gas requires it?
To prevent leakage - Carbon Dioxide (CO2)
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

13. What output on the welding machine is used to rate the duty cycle?
Minutes of elapsed time continually run (out of 10 minutes)
Aluminum wire
Flux cored wires
Shielding the molten weld metal from atmospheric contamination

14. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
85%
Flux cored wires
Constant voltage (CV)
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

15. What 2 organizations designate specifications for GMAW wires?
AWS and CSA
SMAW - GTAW
Generally not as accurate
Duty cycle

16. What happens when the electrode extension is increased?
The resistace to electrical current flow increases with it. Causing the electrode to heat
Wire feed speed - Voltage control
12 to 22 arc volts
Aluminum wire

17. What type of power source is commonly used with a voltage sensing wire feeder?
Dry ice can form within the flow control openings and cause blockage of shielding gas
AWS and CSA
Constant current (CC)
The resistace to electrical current flow increases with it. Causing the electrode to heat

18. Why is globular transfer generally avoided with GMAW?
If you dont know this check your phone
The resistace to electrical current flow increases with it. Causing the electrode to heat
Constant voltage (CV)
Spatter problems and poor weld appearance

19. What type of power source is used with a constant speed wire feeder?
Constant voltage (CV)
DCEP (Direct Current Electrode Positive) Reverse Polarity
5.8 to 12.5 L/min
Gives arc voltage values to the control system of the feeder

20. What is the maximum distance that hard wire can be successfully pushed?
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
Controls the rate of flow of a shielding gas to the gun nozzle
15 feet (4.5 meters)
Gas metal arc welding

21. In the GMAW process what does voltage control?
Motor driven generators - Transformer rectifiers - and Inverter designs
Puddle fluidity
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
To limit the short circuiting current so that spatter is reduced

22. What does inductance control?
Wire feed speed
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)
The time rate of response for the current rise and fall

23. What controls the wire speed on a voltage sensing wire feeder?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Motor driven generators - Transformer rectifiers - and Inverter designs
The Arc voltage
Wire feed speed - Voltage control

24. What is the effect of too much slope?
Minutes of elapsed time continually run (out of 10 minutes)
Insufficient current to melt the wire off cleanly
Speed of the feed motor and - starting / stopping electrode feed
Wire feed speed - Voltage control

25. What is the key advantage of short circuiting transfer?
To limit the short circuiting current so that spatter is reduced
Speed of the feed motor and - starting / stopping electrode feed
Minimum distortion due to low heat input
...

26. What does the wire feeder control?
...
Speed of the feed motor and - starting / stopping electrode feed
Minimum distortion due to low heat input
The negative side of a welding unit

27. What does the abbreviation NEMA stand for?
National Electrical Manufactures Association
The Arc voltage
Reducing the gas source pressure to a constant working pressure
Wire feed speed

28. When is the metal transferred with short circuit transfer?
Shielding the molten weld metal from atmospheric contamination
Generally not as accurate
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
When the filler wire is in direct contract with the base metal

29. What is a solenoid valve and what actuates it?
Puddle fluidity
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
The time rate of response for the current rise and fall
Guns

30. Regulators control_____________ flowmeters SHOW____________.
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Controls the rate of flow of a shielding gas to the gun nozzle
Pressure - The rate of flow of a shielding gas
Wire feeds smoothly (yet will slip should a problem occur in the gun)

31. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Welding process that joins metals by heating them with an electric arc
Voltage is the force that overcomes resistance to allow amperage flow
Guns
Cause flaking - which can clog the liner and contact tube

32. List several industries that would use GMAW
Minutes of elapsed time continually run (out of 10 minutes)
Minimum distortion due to low heat input
Pressure vessels and the piping industry
Short- circuiting transfer - Globular transfer - Spray transfer

33. 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
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Shielding the molten weld metal from atmospheric contamination
Spatter problems and poor weld appearance

34. How many times per second does short circuiting take place?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Wire feed speed
20 to 200 times per second
Higher 26 to 35 arc volts

35. In the GMAW process what does amperage control?
Penetration and burn - off rate of the electrode
Insufficient current to melt the wire off cleanly
...
The Arc voltage

36. List the factors that determine the mode of metal transfer
If you dont know this check your phone
Gas metal arc welding
3
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

37. 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
DCEP (Direct Current Electrode Positive) Reverse Polarity
Minutes of elapsed time continually run (out of 10 minutes)
(DCEP) Direct Current Electrode Positive or Reverse polarity

38. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
Shielding the molten weld metal from atmospheric contamination
...
When the filler wire is in direct contract with the base metal
To prevent leakage - Carbon Dioxide (CO2)

39. What does the term GMAW identify?
Dry ice can form within the flow control openings and cause blockage of shielding gas
12 to 22 arc volts
To prevent drawing of liquid CO2 (Carbon Dioxide)
Gas metal arc welding

40. Give a brief description of the GMAW process
To prevent leakage - Carbon Dioxide (CO2)
Welding process that joins metals by heating them with an electric arc
Reducing the gas source pressure to a constant working pressure
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

41. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Higher 26 to 35 arc volts
Gives arc voltage values to the control system of the feeder
Generally not as accurate
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

42. Draw a typical volt amp curve for a machine that is designed for GMAW
Reducing the gas source pressure to a constant working pressure
If you dont know this check your phone
5.8 to 12.5 L/min
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

43. What processes are constant current (CC) power sources designed to be used with?
Dry ice can form within the flow control openings and cause blockage of shielding gas
1/4 inch to 1/2 inch
SMAW - GTAW
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

44. Why is the term GMAW preferred over MIG or MAG?
Puddle fluidity
Spatter problems and poor weld appearance
These terms are quite restrictive and often technically incorrect
Cause flaking - which can clog the liner and contact tube

45. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
Penetration and burn - off rate of the electrode
Reducing the gas source pressure to a constant working pressure
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
If you dont know this check your phone

46. What does a flowmeter do and what does it measure?
Controls the rate of flow of a shielding gas to the gun nozzle
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
Pressure vessels and the piping industry
Pressure - The rate of flow of a shielding gas

47. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
By there current carrying capacity
The negative side of a welding unit
Short- circuiting transfer - Globular transfer - Spray transfer
(DCEP) Direct Current Electrode Positive or Reverse polarity

48. A pull type drive system is usually used on what type of material?
Constant current (CC)
National Electrical Manufactures Association
Minutes of elapsed time continually run (out of 10 minutes)
Aluminum wire

49. Why is a line heater required when using GMAW?
Minimum distortion due to low heat input
Wire feed speed - Voltage control
Dry ice can form within the flow control openings and cause blockage of shielding gas
...

50. What is the required arc voltage used for short circuit transfer?
Guns
12 to 22 arc volts
To prevent drawing of liquid CO2 (Carbon Dioxide)
To limit the short circuiting current so that spatter is reduced