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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 maximum distance that hard wire can be successfully pushed?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Pressure vessels and the piping industry
When the filler wire is in direct contract with the base metal
15 feet (4.5 meters)

2. What is another term for electrode holders for GMAW?
Shielding the molten weld metal from atmospheric contamination
Voltage is the force that overcomes resistance to allow amperage flow
Guns
(DCEP) Direct Current Electrode Positive or Reverse polarity

3. List the factors that determine the mode of metal transfer
Gives arc voltage values to the control system of the feeder
Constant voltage (CV)
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Gas metal arc welding

4. What are the 2 types of wire feeders available?
15 feet (4.5 meters)
Duty cycle
85%
Constant- speed wire feeders and Voltage- sennsing wire feeders

5. What is the preferred drive roll design for solid wires?
V groove or U groove
Welding process that joins metals by heating them with an electric arc
Wire feed speed - Voltage control
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

6. What type of power source is commonly used with a voltage sensing wire feeder?
Constant current (CC)
Generally not as accurate
National Electrical Manufactures Association
To limit the short circuiting current so that spatter is reduced

7. List 3 forms compressed gases may be supplied for welding
National Electrical Manufactures Association
Controls the rate of flow of a shielding gas to the gun nozzle
AWS and CSA
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

8. What 2 organizations designate specifications for GMAW wires?
Minimum distortion due to low heat input
AWS and CSA
SMAW - GTAW
85%

9. What is the key advantage of short circuiting transfer?
Pressure - The rate of flow of a shielding gas
Minimum distortion due to low heat input
Voltage is the force that overcomes resistance to allow amperage flow
To prevent drawing of liquid CO2 (Carbon Dioxide)

10. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Short- circuiting transfer - Globular transfer - Spray transfer
By there current carrying capacity
Welding process that joins metals by heating them with an electric arc
Higher 26 to 35 arc volts

11. What is an advantage of pulsed arc transfer with GMAW?
Motor driven generators - Transformer rectifiers - and Inverter designs
Dry ice can form within the flow control openings and cause blockage of shielding gas
DCEP (Direct Current Electrode Positive) Reverse Polarity
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

12. What is the required arc voltage used for short circuit transfer?
Reducing the gas source pressure to a constant working pressure
20 to 200 times per second
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12 to 22 arc volts

13. How many times per second does short circuiting take place?
20 to 200 times per second
Wire feed speed - Voltage control
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Constant- speed wire feeders and Voltage- sennsing wire feeders

14. Why is globular transfer generally avoided with GMAW?
Guns
Constant- speed wire feeders and Voltage- sennsing wire feeders
Flux cored wires
Spatter problems and poor weld appearance

15. With straight polarity where is 2/3 of the arc energy?
The negative side of a welding unit
To prevent leakage - Carbon Dioxide (CO2)
Guns
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

16. What would be an indication that the drive roll pressure is adjusted correctly?
Higher 26 to 35 arc volts
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
1/4 inch to 1/2 inch

17. List the three methods of metal transfer with GMAW
Constant voltage (CV)
(DCEP) Direct Current Electrode Positive or Reverse polarity
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Short- circuiting transfer - Globular transfer - Spray transfer

18. Regulators control_____________ flowmeters SHOW____________.
To prevent drawing of liquid CO2 (Carbon Dioxide)
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Pressure - The rate of flow of a shielding gas
Controls the rate of flow of a shielding gas to the gun nozzle

19. What processes are constant current (CC) power sources designed to be used with?
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Motor driven generators - Transformer rectifiers - and Inverter designs
Spatter problems and poor weld appearance
SMAW - GTAW

20. What is the main purpose of 'slope'?
To limit the short circuiting current so that spatter is reduced
Wire feed speed - Voltage control
SMAW - GTAW
To prevent leakage - Carbon Dioxide (CO2)

21. What current and polarity is generally used with GMAW?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Shielding the molten weld metal from atmospheric contamination
Gas metal arc welding
Insufficient current to melt the wire off cleanly

22. What is a solenoid valve and what actuates it?
The negative side of a welding unit
Constant voltage (CV)
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
(DCEP) Direct Current Electrode Positive or Reverse polarity

23. What is the recommended electrode stick- out for .035 solid wire?
1/4 inch to 1/2 inch
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
When the filler wire is in direct contract with the base metal
12 to 22 arc volts

24. A pull type drive system is usually used on what type of material?
Aluminum wire
Generally not as accurate
Penetration and burn - off rate of the electrode
The negative side of a welding unit

25. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
The negative side of a welding unit
1/4 inch to 1/2 inch
Constant voltage (CV)
Gives arc voltage values to the control system of the feeder

26. What does a flowmeter do and what does it measure?
By there current carrying capacity
Gives arc voltage values to the control system of the feeder
Controls the rate of flow of a shielding gas to the gun nozzle
National Electrical Manufactures Association

27. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
To prevent leakage - Carbon Dioxide (CO2)
Pressure vessels and the piping industry
(DCEP) Direct Current Electrode Positive or Reverse polarity
Welding process that joins metals by heating them with an electric arc

28. What is a typical flow rate of CO2 for short circuit transfer?
Constant voltage (CV)
15 feet (4.5 meters)
5.8 to 12.5 L/min
Higher 26 to 35 arc volts

29. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
National Electrical Manufactures Association
Higher 26 to 35 arc volts
3
The resistace to electrical current flow increases with it. Causing the electrode to heat

30. What does voltage do in an electrical circuit?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Voltage is the force that overcomes resistance to allow amperage flow
Short- circuiting transfer - Globular transfer - Spray transfer
By there current carrying capacity

31. What does the abbreviation NEMA stand for?
85%
V groove or U groove
National Electrical Manufactures Association
Wire feed speed - Voltage control

32. What is the effect of too much slope?
Insufficient current to melt the wire off cleanly
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
Voltage is the force that overcomes resistance to allow amperage flow

33. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
Constant current (CC)
...
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
1/4 inch to 1/2 inch

34. What power sources are used with the GMAW Process?
Motor driven generators - Transformer rectifiers - and Inverter designs
Reducing the gas source pressure to a constant working pressure
The negative side of a welding unit
Voltage is the force that overcomes resistance to allow amperage flow

35. Draw a typical volt amp curve for a machine that is designed for GMAW
Motor driven generators - Transformer rectifiers - and Inverter designs
Aluminum wire
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The negative side of a welding unit

36. What controls the wire speed on a voltage sensing wire feeder?
Welding process that joins metals by heating them with an electric arc
The Arc voltage
Constant- speed wire feeders and Voltage- sennsing wire feeders
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37. 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
Insufficient current to melt the wire off cleanly
Flux cored wires
The time rate of response for the current rise and fall

38. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
V groove or U groove
To limit the short circuiting current so that spatter is reduced
85%

39. 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
20 to 200 times per second
The Arc voltage
V groove or U groove

40. 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
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

41. What does the term GMAW identify?
20 to 200 times per second
The resistace to electrical current flow increases with it. Causing the electrode to heat
3
Gas metal arc welding

42. In the GMAW process what does voltage control?
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
Puddle fluidity
15 feet (4.5 meters)

43. What controls amperage when using GMAW?
Short- circuiting transfer - Globular transfer - Spray transfer
Gas metal arc welding
The time rate of response for the current rise and fall
Wire feed speed

44. List 3 wire drive systems and give a short description of each
Cause flaking - which can clog the liner and contact tube
When the filler wire is in direct contract with the base metal
85%
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

45. What 2 controls are found on a GMAW set- up?
Wire feed speed - Voltage control
Puddle fluidity
...
Flux cored wires

46. In the GMAW process what does amperage control?
Voltage is the force that overcomes resistance to allow amperage flow
Speed of the feed motor and - starting / stopping electrode feed
Aluminum wire
Penetration and burn - off rate of the electrode

47. How are GMAW guns rated?
To prevent leakage - Carbon Dioxide (CO2)
Cause flaking - which can clog the liner and contact tube
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

48. What does inductance control?
The time rate of response for the current rise and fall
V groove or U groove
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Motor driven generators - Transformer rectifiers - and Inverter designs

49. What type of power source is used with a constant speed wire feeder?
Shielding the molten weld metal from atmospheric contamination
Duty cycle
Constant voltage (CV)
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

50. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
Gives arc voltage values to the control system of the feeder
5.8 to 12.5 L/min
...
If you dont know this check your phone