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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. Give a brief description of the GMAW process
Welding process that joins metals by heating them with an electric arc
AWS and CSA
Guns
Reducing the gas source pressure to a constant working pressure

2. What is the required arc voltage used for short circuit transfer?
12 to 22 arc volts
Speed of the feed motor and - starting / stopping electrode feed
Motor driven generators - Transformer rectifiers - and Inverter designs
Minimum distortion due to low heat input

3. What type of power source is commonly used with a voltage sensing wire feeder?
If you dont know this check your phone
Pressure vessels and the piping industry
Constant current (CC)
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

4. What is the key advantage of short circuiting transfer?
Constant voltage (CV)
Minimum distortion due to low heat input
To prevent leakage - Carbon Dioxide (CO2)
The time rate of response for the current rise and fall

5. List the three methods of metal transfer with GMAW
Short- circuiting transfer - Globular transfer - Spray transfer
12 to 22 arc volts
To limit the short circuiting current so that spatter is reduced
Gives arc voltage values to the control system of the feeder

6. A pull type drive system is usually used on what type of material?
V groove or U groove
15 feet (4.5 meters)
Aluminum wire
The resistace to electrical current flow increases with it. Causing the electrode to heat

7. In the GMAW process what does voltage control?
Puddle fluidity
AWS and CSA
Motor driven generators - Transformer rectifiers - and Inverter designs
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

8. What is the recommended electrode stick- out for .035 solid wire?
Gas metal arc welding
1/4 inch to 1/2 inch
Gives arc voltage values to the control system of the feeder
Shielding the molten weld metal from atmospheric contamination

9. What does inductance control?
Short- circuiting transfer - Globular transfer - Spray transfer
The time rate of response for the current rise and fall
To prevent leakage - Carbon Dioxide (CO2)
National Electrical Manufactures Association

10. In the GMAW process what does amperage control?
Penetration and burn - off rate of the electrode
5.8 to 12.5 L/min
To limit the short circuiting current so that spatter is reduced
Speed of the feed motor and - starting / stopping electrode feed

11. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Pressure vessels and the piping industry
(DCEP) Direct Current Electrode Positive or Reverse polarity
Motor driven generators - Transformer rectifiers - and Inverter designs
Duty cycle

12. What type of power source is used with a constant speed wire feeder?
85%
15 feet (4.5 meters)
Constant voltage (CV)
V groove or U groove

13. With straight polarity where is 2/3 of the arc energy?
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Puddle fluidity
The negative side of a welding unit
20 to 200 times per second

14. How many times per second does short circuiting take place?
If you dont know this check your phone
Short- circuiting transfer - Globular transfer - Spray transfer
The Arc voltage
20 to 200 times per second

15. What is a solenoid valve and what actuates it?
20 to 200 times per second
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Speed of the feed motor and - starting / stopping electrode feed
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

16. What is a typical flow rate of CO2 for short circuit transfer?
Shielding the molten weld metal from atmospheric contamination
5.8 to 12.5 L/min
The negative side of a welding unit
Voltage is the force that overcomes resistance to allow amperage flow

17. What effect does increasing and decreasing the inductance have on the weld?
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
Voltage is the force that overcomes resistance to allow amperage flow
Pressure vessels and the piping industry

18. List 3 forms compressed gases may be supplied for welding
1/4 inch to 1/2 inch
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
(DCEP) Direct Current Electrode Positive or Reverse polarity

19. Why is a fiber washer required and what cylinder gas requires it?
Generally not as accurate
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
To prevent leakage - Carbon Dioxide (CO2)

20. What are the 2 types of wire feeders available?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Constant voltage (CV)
Constant- speed wire feeders and Voltage- sennsing wire feeders
Flux cored wires

21. List several industries that would use GMAW
Pressure vessels and the piping industry
Puddle fluidity
Pressure - The rate of flow of a shielding gas
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

22. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
Constant current (CC)
Minimum distortion due to low heat input
20 to 200 times per second
85%

23. Regulators control_____________ flowmeters SHOW____________.
Pressure - The rate of flow of a shielding gas
Wire feed speed - Voltage control
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Guns

24. What does the term GMAW identify?
When the filler wire is in direct contract with the base metal
Motor driven generators - Transformer rectifiers - and Inverter designs
(DCEP) Direct Current Electrode Positive or Reverse polarity
Gas metal arc welding

25. What happens when the electrode extension is increased?
Gives arc voltage values to the control system of the feeder
The resistace to electrical current flow increases with it. Causing the electrode to heat
Minutes of elapsed time continually run (out of 10 minutes)
Reducing the gas source pressure to a constant working pressure

26. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Constant current (CC)
Gives arc voltage values to the control system of the feeder
20 to 200 times per second
Dry ice can form within the flow control openings and cause blockage of shielding gas

27. Why is a line heater required when using GMAW?
Dry ice can form within the flow control openings and cause blockage of shielding gas
Penetration and burn - off rate of the electrode
(DCEP) Direct Current Electrode Positive or Reverse polarity
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

28. Why is the term GMAW preferred over MIG or MAG?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Pressure vessels and the piping industry
These terms are quite restrictive and often technically incorrect
Flux cored wires

29. What does the wire feeder control?
Gas metal arc welding
Speed of the feed motor and - starting / stopping electrode feed
Minimum distortion due to low heat input
Wire feed speed - Voltage control

30. What is an advantage of pulsed arc transfer with GMAW?
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
Spatter problems and poor weld appearance
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
V groove or U groove

31. List the factors that determine the mode of metal transfer
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Penetration and burn - off rate of the electrode
By there current carrying capacity
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

32. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Insufficient current to melt the wire off cleanly
Generally not as accurate
The negative side of a welding unit
20 to 200 times per second

33. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
To limit the short circuiting current so that spatter is reduced
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Pressure - The rate of flow of a shielding gas
Higher 26 to 35 arc volts

34. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Shielding the molten weld metal from atmospheric contamination
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
The negative side of a welding unit
Cause flaking - which can clog the liner and contact tube

35. What power sources are used with the GMAW Process?
Motor driven generators - Transformer rectifiers - and Inverter designs
These terms are quite restrictive and often technically incorrect
Pressure vessels and the piping industry
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

36. What does voltage do in an electrical circuit?
12 to 22 arc volts
The Arc voltage
If you dont know this check your phone
Voltage is the force that overcomes resistance to allow amperage flow

37. What is the preferred drive roll design for solid wires?
National Electrical Manufactures Association
V groove or U groove
Voltage is the force that overcomes resistance to allow amperage flow
The negative side of a welding unit

38. Draw a typical volt amp curve for a machine that is designed for GMAW
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
If you dont know this check your phone
Higher 26 to 35 arc volts
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

39. What is the maximum distance that hard wire can be successfully pushed?
Gas metal arc welding
15 feet (4.5 meters)
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Penetration and burn - off rate of the electrode

40. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
1/4 inch to 1/2 inch
(DCEP) Direct Current Electrode Positive or Reverse polarity
If you dont know this check your phone
Puddle fluidity

41. What is another term for electrode holders for GMAW?
Controls the rate of flow of a shielding gas to the gun nozzle
Reducing the gas source pressure to a constant working pressure
Insufficient current to melt the wire off cleanly
Guns

42. Why must CO2 cylinders be used in the vertical position?
To prevent drawing of liquid CO2 (Carbon Dioxide)
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Gas metal arc welding
Aluminum wire

43. What current and polarity is generally used with GMAW?
When the filler wire is in direct contract with the base metal
Reducing the gas source pressure to a constant working pressure
DCEP (Direct Current Electrode Positive) Reverse Polarity
SMAW - GTAW

44. What is the main purpose of 'slope'?
To limit the short circuiting current so that spatter is reduced
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Constant voltage (CV)
1/4 inch to 1/2 inch

45. What does a flowmeter do and what does it measure?
Controls the rate of flow of a shielding gas to the gun nozzle
85%
Voltage is the force that overcomes resistance to allow amperage flow
5.8 to 12.5 L/min

46. When is the metal transferred with short circuit transfer?
Welding process that joins metals by heating them with an electric arc
When the filler wire is in direct contract with the base metal
Voltage is the force that overcomes resistance to allow amperage flow
Short- circuiting transfer - Globular transfer - Spray transfer

47. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
Puddle fluidity
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
V groove or U groove
...

48. List the basic equipment requirements for the GMAW process
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Controls the rate of flow of a shielding gas to the gun nozzle
3
Motor driven generators - Transformer rectifiers - and Inverter designs

49. What does the abbreviation NEMA stand for?
National Electrical Manufactures Association
Cause flaking - which can clog the liner and contact tube
Constant voltage (CV)
20 to 200 times per second

50. What 2 organizations designate specifications for GMAW wires?
AWS and CSA
Wire feeds smoothly (yet will slip should a problem occur in the gun)
1/4 inch to 1/2 inch
(DCEP) Direct Current Electrode Positive or Reverse polarity