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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. Why is a fiber washer required and what cylinder gas requires it?
To prevent leakage - Carbon Dioxide (CO2)
V groove or U groove
These terms are quite restrictive and often technically incorrect
Duty cycle

2. What is the purpose of the shielding gas used in GMAW?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Penetration and burn - off rate of the electrode
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Shielding the molten weld metal from atmospheric contamination

3. What wire are knurled drive rolls most commonly used on?
Short- circuiting transfer - Globular transfer - Spray transfer
Speed of the feed motor and - starting / stopping electrode feed
If you dont know this check your phone
Flux cored wires

4. List 3 forms compressed gases may be supplied for welding
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
3
SMAW - GTAW
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

5. What current and polarity is generally used with GMAW?
Controls the rate of flow of a shielding gas to the gun nozzle
Puddle fluidity
DCEP (Direct Current Electrode Positive) Reverse Polarity
National Electrical Manufactures Association

6. What is another term for electrode holders for GMAW?
Insufficient current to melt the wire off cleanly
V groove or U groove
Guns
The resistace to electrical current flow increases with it. Causing the electrode to heat

7. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
Wire feed speed - Voltage control
Short- circuiting transfer - Globular transfer - Spray transfer
The negative side of a welding unit
85%

8. What is the effect of too much slope?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Insufficient current to melt the wire off cleanly
V groove or U groove
Pressure vessels and the piping industry

9. A 10 minute cycle of welding time vs cooling time a given machine can handle.
The negative side of a welding unit
Duty cycle
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%

10. Give a description of 'pinch effect'
85%
Duty cycle
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

11. What controls the wire speed on a voltage sensing wire feeder?
The Arc voltage
Aluminum wire
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Dry ice can form within the flow control openings and cause blockage of shielding gas

12. What does the abbreviation NEMA stand for?
Duty cycle
Flux cored wires
National Electrical Manufactures Association
Pressure vessels and the piping industry

13. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Short- circuiting transfer - Globular transfer - Spray transfer
Gives arc voltage values to the control system of the feeder
Wire feed speed - Voltage control
Puddle fluidity

14. In the GMAW process what does amperage control?
Penetration and burn - off rate of the electrode
Constant- speed wire feeders and Voltage- sennsing wire feeders
Flux cored wires
Minutes of elapsed time continually run (out of 10 minutes)

15. Why is the term GMAW preferred over MIG or MAG?
These terms are quite restrictive and often technically incorrect
Generally not as accurate
V groove or U groove
Duty cycle

16. What does inductance control?
The time rate of response for the current rise and fall
To prevent leakage - Carbon Dioxide (CO2)
(DCEP) Direct Current Electrode Positive or Reverse polarity
Shielding the molten weld metal from atmospheric contamination

17. 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
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
Cause flaking - which can clog the liner and contact tube
...

18. What does the term GMAW identify?
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
Gas metal arc welding
1/4 inch to 1/2 inch

19. List 3 wire drive systems and give a short description of each
Cause flaking - which can clog the liner and contact tube
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
Wire feed speed
The negative side of a welding unit

20. What is an advantage of pulsed arc transfer with GMAW?
The Arc voltage
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Speed of the feed motor and - starting / stopping electrode feed
Wire feed speed - Voltage control

21. What controls amperage when using GMAW?
12 to 22 arc volts
Wire feed speed
Guns
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

22. What is a typical flow rate of CO2 for short circuit transfer?
By there current carrying capacity
5.8 to 12.5 L/min
12 to 22 arc volts
Voltage is the force that overcomes resistance to allow amperage flow

23. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
3
Shielding the molten weld metal from atmospheric contamination
To limit the short circuiting current so that spatter is reduced
Flux cored wires

24. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
If you dont know this check your phone
(DCEP) Direct Current Electrode Positive or Reverse polarity
Minutes of elapsed time continually run (out of 10 minutes)
Reducing the gas source pressure to a constant working pressure

25. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Generally not as accurate
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
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

26. What are the 2 types of wire feeders available?
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
DCEP (Direct Current Electrode Positive) Reverse Polarity
Voltage is the force that overcomes resistance to allow amperage flow

27. What does a flowmeter do and what does it measure?
Controls the rate of flow of a shielding gas to the gun nozzle
15 feet (4.5 meters)
Pressure - The rate of flow of a shielding gas
Shielding the molten weld metal from atmospheric contamination

28. Give a brief description of the GMAW process
Insufficient current to melt the wire off cleanly
5.8 to 12.5 L/min
Welding process that joins metals by heating them with an electric arc
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

29. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
V groove or U groove
Penetration and burn - off rate of the electrode
Higher 26 to 35 arc volts
Minimum distortion due to low heat input

30. What is the preferred drive roll design for solid wires?
Speed of the feed motor and - starting / stopping electrode feed
V groove or U groove
Pressure - The rate of flow of a shielding gas
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

31. Draw a typical volt amp curve for a machine that is designed for GMAW
Constant voltage (CV)
3
If you dont know this check your phone
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

32. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
Puddle fluidity
If you dont know this check your phone
Shielding the molten weld metal from atmospheric contamination
Wire feed speed

33. What would be an indication that the drive roll pressure is adjusted correctly?
Minimum distortion due to low heat input
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Voltage is the force that overcomes resistance to allow amperage flow
Motor driven generators - Transformer rectifiers - and Inverter designs

34. Regulators control_____________ flowmeters SHOW____________.
Voltage is the force that overcomes resistance to allow amperage flow
The resistace to electrical current flow increases with it. Causing the electrode to heat
Pressure - The rate of flow of a shielding gas
20 to 200 times per second

35. What is the required arc voltage used for 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
DCEP (Direct Current Electrode Positive) Reverse Polarity
12 to 22 arc volts
Motor driven generators - Transformer rectifiers - and Inverter designs

36. What does voltage do in an electrical circuit?
Voltage is the force that overcomes resistance to allow amperage flow
AWS and CSA
Welding process that joins metals by heating them with an electric arc
Wire feed speed - Voltage control

37. How many times per second does short circuiting take place?
5.8 to 12.5 L/min
Spatter problems and poor weld appearance
20 to 200 times per second
Constant voltage (CV)

38. What is the maximum distance that hard wire can be successfully pushed?
Minutes of elapsed time continually run (out of 10 minutes)
Gas metal arc welding
15 feet (4.5 meters)
Penetration and burn - off rate of the electrode

39. What is the recommended electrode stick- out for .035 solid wire?
When the filler wire is in direct contract with the base metal
Penetration and burn - off rate of the electrode
1/4 inch to 1/2 inch
If you dont know this check your phone

40. What is the main purpose of 'slope'?
To limit the short circuiting current so that spatter is reduced
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
85%
Speed of the feed motor and - starting / stopping electrode feed

41. When is the metal transferred with short circuit transfer?
Constant current (CC)
The time rate of response for the current rise and fall
When the filler wire is in direct contract with the base metal
Cause flaking - which can clog the liner and contact tube

42. Why is a line heater required when using GMAW?
Dry ice can form within the flow control openings and cause blockage of shielding gas
Controls the rate of flow of a shielding gas to the gun nozzle
Wire feed speed - Voltage control
85%

43. What effect does increasing and decreasing the inductance have on the weld?
To limit the short circuiting current so that spatter is reduced
Pressure vessels and the piping industry
Shielding the molten weld metal from atmospheric contamination
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

44. How are GMAW guns rated?
The Arc voltage
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
By there current carrying capacity
Insufficient current to melt the wire off cleanly

45. A pull type drive system is usually used on what type of material?
The negative side of a welding unit
By there current carrying capacity
Aluminum wire
To prevent leakage - Carbon Dioxide (CO2)

46. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Gives arc voltage values to the control system of the feeder
Cause flaking - which can clog the liner and contact tube
If you dont know this check your phone
Generally not as accurate

47. What is the key advantage of short circuiting transfer?
Minimum distortion due to low heat input
1/4 inch to 1/2 inch
Wire feed speed
AWS and CSA

48. List several industries that would use GMAW
Pressure vessels and the piping industry
To prevent drawing of liquid CO2 (Carbon Dioxide)
National Electrical Manufactures Association
Puddle fluidity

49. What happens when the electrode extension is increased?
To prevent leakage - Carbon Dioxide (CO2)
The resistace to electrical current flow increases with it. Causing the electrode to heat
Motor driven generators - Transformer rectifiers - and Inverter designs
The time rate of response for the current rise and fall

50. What 2 controls are found on a GMAW set- up?
Wire feed speed - Voltage control
Speed of the feed motor and - starting / stopping electrode feed
The negative side of a welding unit
1/4 inch to 1/2 inch