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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 the basic equipment requirements for the GMAW process
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Gives arc voltage values to the control system of the feeder
20 to 200 times per second
Wire feed speed

2. What happens when the electrode extension is increased?
The resistace to electrical current flow increases with it. Causing the electrode to heat
Insufficient current to melt the wire off cleanly
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
1/4 inch to 1/2 inch

3. What 2 organizations designate specifications for GMAW wires?
...
Guns
DCEP (Direct Current Electrode Positive) Reverse Polarity
AWS and CSA

4. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Voltage is the force that overcomes resistance to allow amperage flow
Wire feed speed
(DCEP) Direct Current Electrode Positive or Reverse polarity
Duty cycle

5. Why is globular transfer generally avoided with GMAW?
Spatter problems and poor weld appearance
(DCEP) Direct Current Electrode Positive or Reverse polarity
DCEP (Direct Current Electrode Positive) Reverse Polarity
Pressure vessels and the piping industry

6. List 3 wire drive systems and give a short description of each
1/4 inch to 1/2 inch
DCEP (Direct Current Electrode Positive) Reverse Polarity
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

7. What does a flowmeter do and what does it measure?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Short- circuiting transfer - Globular transfer - Spray transfer
20 to 200 times per second
Controls the rate of flow of a shielding gas to the gun nozzle

8. What power sources are used with the GMAW Process?
Controls the rate of flow of a shielding gas to the gun nozzle
12 to 22 arc volts
SMAW - GTAW
Motor driven generators - Transformer rectifiers - and Inverter designs

9. Why must CO2 cylinders be used in the vertical position?
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
To prevent drawing of liquid CO2 (Carbon Dioxide)
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
20 to 200 times per second

10. List the factors that determine the mode of metal transfer
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Gives arc voltage values to the control system of the feeder
Minutes of elapsed time continually run (out of 10 minutes)

11. How many times per second does short circuiting take place?
20 to 200 times per second
When the filler wire is in direct contract with the base metal
Spatter problems and poor weld appearance
Minimum distortion due to low heat input

12. What is the recommended electrode stick- out for .035 solid wire?
1/4 inch to 1/2 inch
Pressure - The rate of flow of a shielding gas
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
To limit the short circuiting current so that spatter is reduced

13. What would be an indication that the drive roll pressure is adjusted correctly?
Dry ice can form within the flow control openings and cause blockage of shielding gas
Aluminum wire
AWS and CSA
Wire feeds smoothly (yet will slip should a problem occur in the gun)

14. Regulators control_____________ flowmeters SHOW____________.
Dry ice can form within the flow control openings and cause blockage of shielding gas
Shielding the molten weld metal from atmospheric contamination
Pressure - The rate of flow of a shielding gas
DCEP (Direct Current Electrode Positive) Reverse Polarity

15. 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
To limit the short circuiting current so that spatter is reduced
By there current carrying capacity
15 feet (4.5 meters)

16. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
...
15 feet (4.5 meters)
Insufficient current to melt the wire off cleanly
Aluminum wire

17. What type of power source is used with a constant speed wire feeder?
The Arc voltage
Insufficient current to melt the wire off cleanly
Constant voltage (CV)
To prevent leakage - Carbon Dioxide (CO2)

18. Why is the term GMAW preferred over MIG or MAG?
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
When the filler wire is in direct contract with the base metal
Higher 26 to 35 arc volts

19. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Gives arc voltage values to the control system of the feeder
Gas metal arc welding
Voltage is the force that overcomes resistance to allow amperage flow
Reducing the gas source pressure to a constant working pressure

20. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Pressure vessels and the piping industry
Shielding the molten weld metal from atmospheric contamination
Higher 26 to 35 arc volts
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

21. When is the metal transferred with short circuit transfer?
The resistace to electrical current flow increases with it. Causing the electrode to heat
When the filler wire is in direct contract with the base metal
Puddle fluidity
(DCEP) Direct Current Electrode Positive or Reverse polarity

22. What does the wire feeder control?
Voltage is the force that overcomes resistance to allow amperage flow
Speed of the feed motor and - starting / stopping electrode feed
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

23. What is the effect of too much slope?
Voltage is the force that overcomes resistance to allow amperage flow
Wire feed speed
Insufficient current to melt the wire off cleanly
20 to 200 times per second

24. What does inductance control?
5.8 to 12.5 L/min
The time rate of response for the current rise and fall
Guns
Gas metal arc welding

25. What is the disadvantage of the gauge preset type of regulator/flowmeter?
The time rate of response for the current rise and fall
15 feet (4.5 meters)
Dry ice can form within the flow control openings and cause blockage of shielding gas
Generally not as accurate

26. In the GMAW process what does amperage control?
Penetration and burn - off rate of the electrode
National Electrical Manufactures Association
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Pressure vessels and the piping industry

27. What are the 2 types of wire feeders available?
Insufficient current to melt the wire off cleanly
Gas metal arc welding
Voltage is the force that overcomes resistance to allow amperage flow
Constant- speed wire feeders and Voltage- sennsing wire feeders

28. List the three methods of metal transfer with GMAW
15 feet (4.5 meters)
Flux cored wires
Short- circuiting transfer - Globular transfer - Spray transfer
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

29. In the GMAW process what does voltage control?
Dry ice can form within the flow control openings and cause blockage of shielding gas
To prevent drawing of liquid CO2 (Carbon Dioxide)
Puddle fluidity
85%

30. What wire are knurled drive rolls most commonly used on?
Flux cored wires
If you dont know this check your phone
V groove or U groove
(DCEP) Direct Current Electrode Positive or Reverse polarity

31. What is the key advantage of short circuiting transfer?
Constant current (CC)
Gas metal arc welding
5.8 to 12.5 L/min
Minimum distortion due to low heat input

32. What is the main purpose of 'slope'?
If you dont know this check your phone
Wire feed speed - Voltage control
To limit the short circuiting current so that spatter is reduced
Wire feeds smoothly (yet will slip should a problem occur in the gun)

33. Why is a fiber washer required and what cylinder gas requires it?
Generally not as accurate
V groove or U groove
SMAW - GTAW
To prevent leakage - Carbon Dioxide (CO2)

34. What is the required arc voltage used for short circuit transfer?
Flux cored wires
12 to 22 arc volts
The Arc voltage
If you dont know this check your phone

35. A pull type drive system is usually used on what type of material?
Penetration and burn - off rate of the electrode
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Aluminum wire
Shielding the molten weld metal from atmospheric contamination

36. What is a solenoid valve and what actuates it?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Higher 26 to 35 arc volts
Aluminum wire
Short- circuiting transfer - Globular transfer - Spray transfer

37. List 3 forms compressed gases may be supplied for welding
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Gas metal arc welding
If you dont know this check your phone
20 to 200 times per second

38. What is the purpose of a regulator and what does it indicate on its gauges?
Gives arc voltage values to the control system of the feeder
Higher 26 to 35 arc volts
The negative side of a welding unit
Reducing the gas source pressure to a constant working pressure

39. What is a typical flow rate of CO2 for short circuit transfer?
5.8 to 12.5 L/min
Voltage is the force that overcomes resistance to allow amperage flow
85%
To limit the short circuiting current so that spatter is reduced

40. What 2 controls are found on a GMAW set- up?
Penetration and burn - off rate of the electrode
To prevent drawing of liquid CO2 (Carbon Dioxide)
National Electrical Manufactures Association
Wire feed speed - Voltage control

41. List several industries that would use GMAW
Constant current (CC)
Pressure vessels and the piping industry
Gas metal arc welding
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

42. What controls amperage when using GMAW?
Aluminum wire
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Wire feed speed
5.8 to 12.5 L/min

43. How are GMAW guns rated?
(DCEP) Direct Current Electrode Positive or Reverse polarity
By there current carrying capacity
Short- circuiting transfer - Globular transfer - Spray transfer
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

44. With straight polarity where is 2/3 of the arc energy?
Dry ice can form within the flow control openings and cause blockage of shielding gas
V groove or U groove
Penetration and burn - off rate of the electrode
The negative side of a welding unit

45. What is the purpose of the shielding gas used in GMAW?
Shielding the molten weld metal from atmospheric contamination
Minimum distortion due to low heat input
These terms are quite restrictive and often technically incorrect
20 to 200 times per second

46. What current and polarity is generally used with GMAW?
Puddle fluidity
Reducing the gas source pressure to a constant working pressure
DCEP (Direct Current Electrode Positive) Reverse Polarity
...

47. What output on the welding machine is used to rate the duty cycle?
(DCEP) Direct Current Electrode Positive or Reverse polarity
Minutes of elapsed time continually run (out of 10 minutes)
Pressure - The rate of flow of a shielding gas
5.8 to 12.5 L/min

48. What is the maximum distance that hard wire can be successfully pushed?
Puddle fluidity
Wire feed speed
These terms are quite restrictive and often technically incorrect
15 feet (4.5 meters)

49. What does the abbreviation NEMA stand for?
Aluminum wire
Constant voltage (CV)
National Electrical Manufactures Association
The negative side of a welding unit

50. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
Aluminum wire
(DCEP) Direct Current Electrode Positive or Reverse polarity
Reducing the gas source pressure to a constant working pressure
Minimum distortion due to low heat input