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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. List 3 wire drive systems and give a short description of each
By there current carrying capacity
These terms are quite restrictive and often technically incorrect
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
Insufficient current to melt the wire off cleanly

2. What type of power source is commonly used with a voltage sensing wire feeder?
Gas metal arc welding
Constant current (CC)
To limit the short circuiting current so that spatter is reduced
Welding process that joins metals by heating them with an electric arc

3. In the GMAW process what does amperage control?
Penetration and burn - off rate of the electrode
The Arc voltage
Generally not as accurate
Voltage is the force that overcomes resistance to allow amperage flow

4. What is the purpose of a regulator and what does it indicate on its gauges?
Wire feed speed - Voltage 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
Pressure - The rate of flow of a shielding gas
Reducing the gas source pressure to a constant working pressure

5. What does a flowmeter do and what does it measure?
15 feet (4.5 meters)
Welding process that joins metals by heating them with an electric arc
The resistace to electrical current flow increases with it. Causing the electrode to heat
Controls the rate of flow of a shielding gas to the gun nozzle

6. What wire are knurled drive rolls most commonly used on?
Constant- speed wire feeders and Voltage- sennsing wire feeders
Flux cored wires
Wire feed speed
Constant voltage (CV)

7. When is the metal transferred with short circuit transfer?
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
When the filler wire is in direct contract with the base metal
Generally not as accurate
To limit the short circuiting current so that spatter is reduced

8. What does the term GMAW identify?
The resistace to electrical current flow increases with it. Causing the electrode to heat
15 feet (4.5 meters)
Gas metal arc welding
12 to 22 arc volts

9. What is an advantage of pulsed arc transfer with GMAW?
These terms are quite restrictive and often technically incorrect
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Constant- speed wire feeders and Voltage- sennsing wire feeders
National Electrical Manufactures Association

10. Why must CO2 cylinders be used in the vertical position?
Shielding the molten weld metal from atmospheric contamination
To prevent drawing of liquid CO2 (Carbon Dioxide)
Reducing the gas source pressure to a constant working pressure
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11. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Duty cycle
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Constant- speed wire feeders and Voltage- sennsing wire feeders
Cause flaking - which can clog the liner and contact tube

12. What is the effect of too much slope?
Insufficient current to melt the wire off cleanly
20 to 200 times per second
Welding process that joins metals by heating them with an electric arc
Generally not as accurate

13. What is the main purpose of 'slope'?
To limit the short circuiting current so that spatter is reduced
Voltage is the force that overcomes resistance to allow amperage flow
Speed of the feed motor and - starting / stopping electrode feed
Dry ice can form within the flow control openings and cause blockage of shielding gas

14. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
If you dont know this check your phone
AWS and CSA
...
The Arc voltage

15. Why is a fiber washer required and what cylinder gas requires it?
These terms are quite restrictive and often technically incorrect
Constant voltage (CV)
Shielding the molten weld metal from atmospheric contamination
To prevent leakage - Carbon Dioxide (CO2)

16. List the three methods of metal transfer with GMAW
Puddle fluidity
Short- circuiting transfer - Globular transfer - Spray transfer
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
National Electrical Manufactures Association

17. What power sources are used with the GMAW Process?
Motor driven generators - Transformer rectifiers - and Inverter designs
DCEP (Direct Current Electrode Positive) Reverse Polarity
Shielding the molten weld metal from atmospheric contamination
Duty cycle

18. What is the required arc voltage used for short circuit transfer?
20 to 200 times per second
12 to 22 arc volts
Voltage is the force that overcomes resistance to allow amperage flow
Constant current (CC)

19. With straight polarity where is 2/3 of the arc energy?
Speed of the feed motor and - starting / stopping electrode feed
The negative side of a welding unit
To limit the short circuiting current so that spatter is reduced
If you dont know this check your phone

20. What is the recommended electrode stick- out for .035 solid wire?
Reducing the gas source pressure to a constant working pressure
15 feet (4.5 meters)
1/4 inch to 1/2 inch
5.8 to 12.5 L/min

21. 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
Generally not as accurate
85%

22. What does inductance control?
The time rate of response for the current rise and fall
The Arc voltage
Constant voltage (CV)
AWS and CSA

23. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Pressure - The rate of flow of a shielding gas
Puddle fluidity
Generally not as accurate

24. What is the key advantage of short circuiting transfer?
3
Spatter problems and poor weld appearance
Minimum distortion due to low heat input
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

25. A pull type drive system is usually used on what type of material?
SMAW - GTAW
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Insufficient current to melt the wire off cleanly
Aluminum wire

26. What is the preferred drive roll design for solid wires?
V groove or U groove
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
15 feet (4.5 meters)
AWS and CSA

27. What is another term for electrode holders for GMAW?
5.8 to 12.5 L/min
Motor driven generators - Transformer rectifiers - and Inverter designs
Guns
15 feet (4.5 meters)

28. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Minutes of elapsed time continually run (out of 10 minutes)
Cause flaking - which can clog the liner and contact tube
National Electrical Manufactures Association
Gives arc voltage values to the control system of the feeder

29. List the basic equipment requirements for the GMAW process
Motor driven generators - Transformer rectifiers - and Inverter designs
Pressure vessels and the piping industry
Cause flaking - which can clog the liner and contact tube
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

30. What 2 organizations designate specifications for GMAW wires?
The resistace to electrical current flow increases with it. Causing the electrode to heat
1/4 inch to 1/2 inch
Pressure - The rate of flow of a shielding gas
AWS and CSA

31. What output on the welding machine is used to rate the duty cycle?
The Arc voltage
3
Shielding the molten weld metal from atmospheric contamination
Minutes of elapsed time continually run (out of 10 minutes)

32. What processes are constant current (CC) power sources designed to be used with?
SMAW - GTAW
To prevent drawing of liquid CO2 (Carbon Dioxide)
Gas metal arc welding
Shielding the molten weld metal from atmospheric contamination

33. What is the purpose of the shielding gas used in GMAW?
Shielding the molten weld metal from atmospheric contamination
Pressure - The rate of flow of a shielding gas
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
The time rate of response for the current rise and fall

34. Draw a typical volt amp curve for a machine that is designed for GMAW
If you dont know this check your phone
Pressure - The rate of flow of a shielding gas
When the filler wire is in direct contract with the base metal
The resistace to electrical current flow increases with it. Causing the electrode to heat

35. What are the 2 types of wire feeders available?
The resistace to electrical current flow increases with it. Causing the electrode to heat
Flux cored wires
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

36. What type of power source is used with a constant speed wire feeder?
Wire feed speed
Flux cored wires
Constant voltage (CV)
The time rate of response for the current rise and fall

37. Regulators control_____________ flowmeters SHOW____________.
SMAW - GTAW
National Electrical Manufactures Association
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 - The rate of flow of a shielding gas

38. In the GMAW process what does voltage control?
Speed of the feed motor and - starting / stopping electrode feed
Aluminum wire
Puddle fluidity
Dry ice can form within the flow control openings and cause blockage of shielding gas

39. List several industries that would use GMAW
Pressure vessels and the piping industry
National Electrical Manufactures Association
Constant current (CC)
Voltage is the force that overcomes resistance to allow amperage flow

40. What does voltage do in an electrical circuit?
AWS and CSA
Gas metal arc welding
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
Voltage is the force that overcomes resistance to allow amperage flow

41. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
3
To prevent drawing of liquid CO2 (Carbon Dioxide)
When the filler wire is in direct contract with the base metal

42. Give a description of 'pinch effect'
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
15 feet (4.5 meters)
Welding process that joins metals by heating them with an electric arc
Cause flaking - which can clog the liner and contact tube

43. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Flux cored wires
Cause flaking - which can clog the liner and contact tube
Short- circuiting transfer - Globular transfer - Spray transfer
DCEP (Direct Current Electrode Positive) Reverse Polarity

44. 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
Minutes of elapsed time continually run (out of 10 minutes)
15 feet (4.5 meters)
Higher 26 to 35 arc volts

45. List the factors that determine the mode of metal transfer
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
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
Wire feed speed

46. Why is the term GMAW preferred over MIG or MAG?
Short- circuiting transfer - Globular transfer - Spray transfer
These terms are quite restrictive and often technically incorrect
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Spatter problems and poor weld appearance

47. What 2 controls are found on a GMAW set- up?
Wire feed speed - 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
Penetration and burn - off rate of the electrode
Constant current (CC)

48. What is a solenoid valve and what actuates it?
The Arc voltage
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Dry ice can form within the flow control openings and cause blockage of shielding gas
20 to 200 times per second

49. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
5.8 to 12.5 L/min
(DCEP) Direct Current Electrode Positive or Reverse polarity
The time rate of response for the current rise and fall
Constant voltage (CV)

50. What would be an indication that the drive roll pressure is adjusted correctly?
To prevent drawing of liquid CO2 (Carbon Dioxide)
Wire feeds smoothly (yet will slip should a problem occur in the gun)
15 feet (4.5 meters)
Minimum distortion due to low heat input