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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 power sources are used with the GMAW Process?
Minutes of elapsed time continually run (out of 10 minutes)
Wire feed speed
Controls the rate of flow of a shielding gas to the gun nozzle
Motor driven generators - Transformer rectifiers - and Inverter designs

2. What is an advantage of pulsed arc transfer with GMAW?
3
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
These terms are quite restrictive and often technically incorrect
The negative side of a welding unit

3. What controls amperage when using GMAW?
Wire feed speed
Flux cored wires
Minutes of elapsed time continually run (out of 10 minutes)
Penetration and burn - off rate of the electrode

4. What type of power source is used with a constant speed wire feeder?
Dry ice can form within the flow control openings and cause blockage of shielding gas
85%
Constant voltage (CV)
Cause flaking - which can clog the liner and contact tube

5. What processes are constant current (CC) power sources designed to be used with?
The negative side of a welding unit
Minimum distortion due to low heat input
Generally not as accurate
SMAW - GTAW

6. What is the purpose of the shielding gas used in GMAW?
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Flux cored wires
Shielding the molten weld metal from atmospheric contamination
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

7. What effect does increasing and decreasing the inductance have on the weld?
V groove or U groove
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
The Arc voltage
Minimum distortion due to low heat input

8. What does a flowmeter do and what does it measure?
Cause flaking - which can clog the liner and contact tube
5.8 to 12.5 L/min
Welding process that joins metals by heating them with an electric arc
Controls the rate of flow of a shielding gas to the gun nozzle

9. What output on the welding machine is used to rate the duty cycle?
Puddle fluidity
Minutes of elapsed time continually run (out of 10 minutes)
If you dont know this check your phone
Pressure - The rate of flow of a shielding gas

10. Why is a line heater required when using GMAW?
Reducing the gas source pressure to a constant working pressure
Dry ice can form within the flow control openings and cause blockage of shielding gas
Duty cycle
Welding process that joins metals by heating them with an electric arc

11. A pull type drive system is usually used on what type of material?
Constant current (CC)
SMAW - GTAW
Wire feed speed - Voltage control
Aluminum wire

12. What is the key advantage of short circuiting transfer?
Insufficient current to melt the wire off cleanly
Minimum distortion due to low heat input
Generally not as accurate
Higher 26 to 35 arc volts

13. Give a brief description of the GMAW process
AWS and CSA
Constant current (CC)
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Welding process that joins metals by heating them with an electric arc

14. What does the term GMAW identify?
Flux cored wires
Gas metal arc welding
3
Spatter problems and poor weld appearance

15. What happens when the electrode extension is increased?
...
The resistace to electrical current flow increases with it. Causing the electrode to heat
Constant- speed wire feeders and Voltage- sennsing wire feeders
Insufficient current to melt the wire off cleanly

16. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
85%
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
SMAW - GTAW
Welding process that joins metals by heating them with an electric arc

17. What would be an indication that the drive roll pressure is adjusted correctly?
Penetration and burn - off rate of the electrode
The time rate of response for the current rise and fall
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Minimum distortion due to low heat input

18. How many times per second does short circuiting take place?
20 to 200 times per second
85%
These terms are quite restrictive and often technically incorrect
Speed of the feed motor and - starting / stopping electrode feed

19. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
The Arc voltage
85%
...
If you dont know this check your phone

20. 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)
Minutes of elapsed time continually run (out of 10 minutes)
SMAW - GTAW

21. What does the abbreviation NEMA stand for?
Minimum distortion due to low heat input
National Electrical Manufactures Association
When the filler wire is in direct contract with the base metal
Cause flaking - which can clog the liner and contact tube

22. Why is the term GMAW preferred over MIG or MAG?
Spatter problems and poor weld appearance
These terms are quite restrictive and often technically incorrect
Generally not as accurate
3

23. Regulators control_____________ flowmeters SHOW____________.
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
The time rate of response for the current rise and fall
Pressure - The rate of flow of a shielding gas
Constant- speed wire feeders and Voltage- sennsing wire feeders

24. Give a description of 'pinch effect'
By there current carrying capacity
(DCEP) Direct Current Electrode Positive or Reverse polarity
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Reducing the gas source pressure to a constant working pressure

25. What are the 2 types of wire feeders available?
Constant- speed wire feeders and Voltage- sennsing wire feeders
15 feet (4.5 meters)
Flux cored wires
These terms are quite restrictive and often technically incorrect

26. What wire are knurled drive rolls most commonly used on?
Flux cored wires
3
Guns
The Arc voltage

27. What is a typical flow rate of CO2 for short circuit transfer?
5.8 to 12.5 L/min
15 feet (4.5 meters)
These terms are quite restrictive and often technically incorrect
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

28. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
(DCEP) Direct Current Electrode Positive or Reverse polarity
The Arc voltage
Pressure vessels and the piping industry
AWS and CSA

29. When is the metal transferred with short circuit transfer?
Gas metal arc welding
These terms are quite restrictive and often technically incorrect
Higher 26 to 35 arc volts
When the filler wire is in direct contract with the base metal

30. List the basic equipment requirements for the GMAW process
Welding process that joins metals by heating them with an electric arc
AWS and CSA
15 feet (4.5 meters)
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

31. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Generally not as accurate
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

32. What does inductance control?
The time rate of response for the current rise and fall
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Penetration and burn - off rate of the electrode
Controls the rate of flow of a shielding gas to the gun nozzle

33. What is the effect of too much slope?
Cause flaking - which can clog the liner and contact tube
The negative side of a welding unit
Insufficient current to melt the wire off cleanly
Motor driven generators - Transformer rectifiers - and Inverter designs

34. What does the wire feeder control?
Penetration and burn - off rate of the electrode
Aluminum wire
Speed of the feed motor and - starting / stopping electrode feed
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

35. With straight polarity where is 2/3 of the arc energy?
The negative side of a welding unit
Pressure vessels and the piping industry
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
(DCEP) Direct Current Electrode Positive or Reverse polarity

36. What is the preferred drive roll design for solid wires?
National Electrical Manufactures Association
Wire feeds smoothly (yet will slip should a problem occur in the gun)
V groove or U groove
The time rate of response for the current rise and fall

37. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
If you dont know this check your phone
Guns
Higher 26 to 35 arc volts
Constant- speed wire feeders and Voltage- sennsing wire feeders

38. What is a solenoid valve and what actuates it?
The time rate of response for the current rise and fall
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Penetration and burn - off rate of the electrode
Duty cycle

39. Why is a fiber washer required and what cylinder gas requires it?
85%
National Electrical Manufactures Association
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
To prevent leakage - Carbon Dioxide (CO2)

40. In the GMAW process what does voltage control?
Wire feed speed
The resistace to electrical current flow increases with it. Causing the electrode to heat
Puddle fluidity
Minimum distortion due to low heat input

41. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
V groove or U groove
The time rate of response for the current rise and fall
12 to 22 arc volts
3

42. What current and polarity is generally used with GMAW?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Controls the rate of flow of a shielding gas to the gun nozzle
3
Aluminum wire

43. In the GMAW process what does amperage control?
15 feet (4.5 meters)
Insufficient current to melt the wire off cleanly
Constant current (CC)
Penetration and burn - off rate of the electrode

44. What is another term for electrode holders for GMAW?
Guns
Constant- speed wire feeders and Voltage- sennsing wire feeders
Voltage is the force that overcomes resistance to allow amperage flow
15 feet (4.5 meters)

45. What is the purpose of a regulator and what does it indicate on its gauges?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Reducing the gas source pressure to a constant working pressure
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Pressure - The rate of flow of a shielding gas

46. 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)
By there current carrying capacity
Gives arc voltage values to the control system of the feeder
12 to 22 arc volts

47. What is the recommended electrode stick- out for .035 solid wire?
1/4 inch to 1/2 inch
Minimum distortion due to low heat input
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
To prevent leakage - Carbon Dioxide (CO2)

48. What is the maximum distance that hard wire can be successfully pushed?
If you dont know this check your phone
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
The negative side of a welding unit
15 feet (4.5 meters)

49. What controls the wire speed on a voltage sensing wire feeder?
Constant- speed wire feeders and Voltage- sennsing wire feeders
SMAW - GTAW
1/4 inch to 1/2 inch
The Arc voltage

50. What is the main purpose of 'slope'?
Constant- speed wire feeders and Voltage- sennsing wire feeders
15 feet (4.5 meters)
AWS and CSA
To limit the short circuiting current so that spatter is reduced