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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 2 organizations designate specifications for GMAW wires?
5.8 to 12.5 L/min
Insufficient current to melt the wire off cleanly
Duty cycle
AWS and CSA

2. A pull type drive system is usually used on what type of material?
Controls the rate of flow of a shielding gas to the gun nozzle
Aluminum wire
Generally not as accurate
Insufficient current to melt the wire off cleanly

3. What is a solenoid valve and what actuates it?
5.8 to 12.5 L/min
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
The Arc voltage
Pressure - The rate of flow of a shielding gas

4. What wire are knurled drive rolls most commonly used on?
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
12 to 22 arc volts
Flux cored wires

5. What is another term for electrode holders for GMAW?
Motor driven generators - Transformer rectifiers - and Inverter designs
Wire feeds smoothly (yet will slip should a problem occur in the gun)
V groove or U groove
Guns

6. What is the key advantage of short circuiting transfer?
Minimum distortion due to low heat input
Minutes of elapsed time continually run (out of 10 minutes)
Higher 26 to 35 arc volts
To prevent drawing of liquid CO2 (Carbon Dioxide)

7. What is an advantage of pulsed arc transfer with GMAW?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Aluminum wire
20 to 200 times per second
SMAW - GTAW

8. What type of power source is commonly used with a voltage sensing wire feeder?
Cause flaking - which can clog the liner and contact tube
Minimum distortion due to low heat input
The resistace to electrical current flow increases with it. Causing the electrode to heat
Constant current (CC)

9. What is the required arc voltage used for short circuit transfer?
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
Motor driven generators - Transformer rectifiers - and Inverter designs
12 to 22 arc volts

10. List the basic equipment requirements for the GMAW process
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
National Electrical Manufactures Association
Duty cycle
20 to 200 times per second

11. List 3 forms compressed gases may be supplied for welding
Aluminum wire
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
20 to 200 times per second

12. Why is a fiber washer required and what cylinder gas requires it?
Minimum distortion due to low heat input
By there current carrying capacity
Welding process that joins metals by heating them with an electric arc
To prevent leakage - Carbon Dioxide (CO2)

13. What are the 2 types of wire feeders available?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
These terms are quite restrictive and often technically incorrect
Constant- speed wire feeders and Voltage- sennsing wire feeders
The negative side of a welding unit

14. What does the abbreviation NEMA stand for?
National Electrical Manufactures Association
1/4 inch to 1/2 inch
Higher 26 to 35 arc volts
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

15. What current and polarity is generally used with GMAW?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Wire feed speed - Voltage control
SMAW - GTAW
These terms are quite restrictive and often technically incorrect

16. With straight polarity where is 2/3 of the arc energy?
The time rate of response for the current rise and fall
The negative side of a welding unit
3
To limit the short circuiting current so that spatter is reduced

17. What output on the welding machine is used to rate the duty cycle?
Minutes of elapsed time continually run (out of 10 minutes)
Motor driven generators - Transformer rectifiers - and Inverter designs
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

18. Why must CO2 cylinders be used in the vertical position?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
To prevent drawing of liquid CO2 (Carbon Dioxide)
1/4 inch to 1/2 inch
Shielding the molten weld metal from atmospheric contamination

19. What is the effect of too much slope?
To prevent leakage - Carbon Dioxide (CO2)
Generally not as accurate
1/4 inch to 1/2 inch
Insufficient current to melt the wire off cleanly

20. In the GMAW process what does amperage control?
Penetration and burn - off rate of the electrode
Aluminum wire
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
Minimum distortion due to low heat input

21. Why is globular transfer generally avoided with GMAW?
Spatter problems and poor weld appearance
Wire feed speed
AWS and CSA
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

22. Give a brief description of the GMAW process
Welding process that joins metals by heating them with an electric arc
Constant current (CC)
Voltage is the force that overcomes resistance to allow amperage flow
(DCEP) Direct Current Electrode Positive or Reverse polarity

23. What is the disadvantage of the gauge preset type of regulator/flowmeter?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Penetration and burn - off rate of the electrode
These terms are quite restrictive and often technically incorrect
Generally not as accurate

24. Why is the term GMAW preferred over MIG or MAG?
These terms are quite restrictive and often technically incorrect
Constant- speed wire feeders and Voltage- sennsing wire feeders
Flux cored wires
If you dont know this check your phone

25. What does a flowmeter do and what does it measure?
Controls the rate of flow of a shielding gas to the gun nozzle
To prevent drawing of liquid CO2 (Carbon Dioxide)
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Reducing the gas source pressure to a constant working pressure

26. What does voltage do in an electrical circuit?
Wire feed speed
Constant current (CC)
Insufficient current to melt the wire off cleanly
Voltage is the force that overcomes resistance to allow amperage flow

27. What controls the wire speed on a voltage sensing wire feeder?
3
Shielding the molten weld metal from atmospheric contamination
To prevent drawing of liquid CO2 (Carbon Dioxide)
The Arc voltage

28. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
Short- circuiting transfer - Globular transfer - Spray transfer
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
If you dont know this check your phone
DCEP (Direct Current Electrode Positive) Reverse Polarity

29. What power sources are used with the GMAW Process?
Duty cycle
Motor driven generators - Transformer rectifiers - and Inverter designs
These terms are quite restrictive and often technically incorrect
DCEP (Direct Current Electrode Positive) Reverse Polarity

30. Draw a typical volt amp curve for a machine that is designed for GMAW
DCEP (Direct Current Electrode Positive) Reverse Polarity
SMAW - GTAW
If you dont know this check your phone
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

31. What does the term GMAW identify?
Cause flaking - which can clog the liner and contact tube
20 to 200 times per second
Short- circuiting transfer - Globular transfer - Spray transfer
Gas metal arc welding

32. What is the purpose of the shielding gas used in GMAW?
1/4 inch to 1/2 inch
Guns
Shielding the molten weld metal from atmospheric contamination
5.8 to 12.5 L/min

33. How many times per second does short circuiting take place?
Pressure - The rate of flow of a shielding gas
To prevent leakage - Carbon Dioxide (CO2)
20 to 200 times per second
(DCEP) Direct Current Electrode Positive or Reverse polarity

34. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
If you dont know this check your phone
85%
3
Wire feed speed - Voltage control

35. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
The resistace to electrical current flow increases with it. Causing the electrode to heat
Gives arc voltage values to the control system of the feeder
Gas metal arc welding
Spatter problems and poor weld appearance

36. What does the wire feeder control?
(DCEP) Direct Current Electrode Positive or Reverse polarity
Motor driven generators - Transformer rectifiers - and Inverter designs
To prevent leakage - Carbon Dioxide (CO2)
Speed of the feed motor and - starting / stopping electrode feed

37. What does inductance control?
The time rate of response for the current rise and fall
Cause flaking - which can clog the liner and contact tube
Reducing the gas source pressure to a constant working pressure
The resistace to electrical current flow increases with it. Causing the electrode to heat

38. In the GMAW process what does voltage control?
5.8 to 12.5 L/min
Puddle fluidity
15 feet (4.5 meters)
1/4 inch to 1/2 inch

39. How are GMAW guns rated?
Shielding the molten weld metal from atmospheric contamination
Dry ice can form within the flow control openings and cause blockage of shielding gas
SMAW - GTAW
By there current carrying capacity

40. What is the recommended electrode stick- out for .035 solid wire?
20 to 200 times per second
1/4 inch to 1/2 inch
Cause flaking - which can clog the liner and contact tube
Generally not as accurate

41. What is the main purpose of 'slope'?
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
If you dont know this check your phone
Higher 26 to 35 arc volts

42. List 3 wire drive systems and give a short description of each
Gives arc voltage values to the control system of the feeder
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
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
1/4 inch to 1/2 inch

43. What effect does increasing and decreasing the inductance have on the weld?
The time rate of response for the current rise and fall
Aluminum wire
Wire feeds smoothly (yet will slip should a problem occur in the gun)
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. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Pressure vessels and the piping industry
The time rate of response for the current rise and fall
Duty cycle
Speed of the feed motor and - starting / stopping electrode feed

45. What happens when the electrode extension is increased?
Minimum distortion due to low heat input
The resistace to electrical current flow increases with it. Causing the electrode to heat
If you dont know this check your phone
These terms are quite restrictive and often technically incorrect

46. Why is a line heater required when using GMAW?
Dry ice can form within the flow control openings and cause blockage of shielding gas
Insufficient current to melt the wire off cleanly
The resistace to electrical current flow increases with it. Causing the electrode to heat
DCEP (Direct Current Electrode Positive) Reverse Polarity

47. What is a typical flow rate of CO2 for short circuit transfer?
5.8 to 12.5 L/min
National Electrical Manufactures Association
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Penetration and burn - off rate of the electrode

48. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Gas metal arc welding
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
If you dont know this check your phone

49. What controls amperage when using GMAW?
Reducing the gas source pressure to a constant working pressure
Insufficient current to melt the wire off cleanly
Pressure - The rate of flow of a shielding gas
Wire feed speed

50. What type of power source is used with a constant speed wire feeder?
When the filler wire is in direct contract with the base metal
Spatter problems and poor weld appearance
Constant voltage (CV)
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground