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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 type of power source is commonly used with a voltage sensing wire feeder?
Constant current (CC)
The negative side of a welding unit
V groove or U groove
To limit the short circuiting current so that spatter is reduced

2. What output on the welding machine is used to rate the duty cycle?
Minutes of elapsed time continually run (out of 10 minutes)
Pressure - The rate of flow of a shielding gas
Voltage is the force that overcomes resistance to allow amperage flow
85%

3. What does the abbreviation NEMA stand for?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
If you dont know this check your phone
To prevent leakage - Carbon Dioxide (CO2)
National Electrical Manufactures Association

4. What wire are knurled drive rolls most commonly used on?
Spatter problems and poor weld appearance
Flux cored wires
(DCEP) Direct Current Electrode Positive or Reverse polarity
To prevent leakage - Carbon Dioxide (CO2)

5. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
15 feet (4.5 meters)
85%
Higher 26 to 35 arc volts
Dry ice can form within the flow control openings and cause blockage of shielding gas

6. What effect does increasing and decreasing the inductance have on the weld?
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
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Generally not as accurate

7. What type of power source is used with a constant speed wire feeder?
Wire feed speed
12 to 22 arc volts
Constant voltage (CV)
By there current carrying capacity

8. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Aluminum wire
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
DCEP (Direct Current Electrode Positive) Reverse Polarity
Gives arc voltage values to the control system of the feeder

9. Give a description of 'pinch effect'
Wire feed speed
SMAW - GTAW
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
The resistace to electrical current flow increases with it. Causing the electrode to heat

10. Why is a fiber washer required and what cylinder gas requires it?
Dry ice can form within the flow control openings and cause blockage of shielding gas
Duty cycle
To prevent leakage - Carbon Dioxide (CO2)
Controls the rate of flow of a shielding gas to the gun nozzle

11. A pull type drive system is usually used on what type of material?
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
Aluminum wire
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Puddle fluidity

12. What controls amperage when using GMAW?
Generally not as accurate
These terms are quite restrictive and often technically incorrect
1/4 inch to 1/2 inch
Wire feed speed

13. What is the required arc voltage used for short circuit transfer?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Constant voltage (CV)
Penetration and burn - off rate of the electrode
12 to 22 arc volts

14. What is the effect of too much slope?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Cause flaking - which can clog the liner and contact tube
Insufficient current to melt the wire off cleanly
If you dont know this check your phone

15. In the GMAW process what does amperage control?
Short- circuiting transfer - Globular transfer - Spray transfer
Penetration and burn - off rate of the electrode
Dry ice can form within the flow control openings and cause blockage of shielding gas
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

16. What current and polarity is generally used with GMAW?
3
The negative side of a welding unit
DCEP (Direct Current Electrode Positive) Reverse Polarity
Puddle fluidity

17. How many times per second does short circuiting take place?
85%
Wire feeds smoothly (yet will slip should a problem occur in the gun)
The time rate of response for the current rise and fall
20 to 200 times per second

18. What is the purpose of the shielding gas used in GMAW?
85%
Insufficient current to melt the wire off cleanly
Duty cycle
Shielding the molten weld metal from atmospheric contamination

19. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Controls the rate of flow of a shielding gas to the gun nozzle
The resistace to electrical current flow increases with it. Causing the electrode to heat
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Cause flaking - which can clog the liner and contact tube

20. What is another term for electrode holders for GMAW?
Reducing the gas source pressure to a constant working pressure
Guns
Speed of the feed motor and - starting / stopping electrode feed
If you dont know this check your phone

21. What does inductance control?
The time rate of response for the current rise and fall
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
Constant current (CC)

22. Draw a typical volt amp curve for a machine that is designed for GMAW
Voltage is the force that overcomes resistance to allow amperage flow
Pressure - The rate of flow of a shielding gas
National Electrical Manufactures Association
If you dont know this check your phone

23. List 3 wire drive systems and give a short description of each
Speed of the feed motor and - starting / stopping electrode feed
These terms are quite restrictive and often technically incorrect
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
Gives arc voltage values to the control system of the feeder

24. What 2 organizations designate specifications for GMAW wires?
Welding process that joins metals by heating them with an electric arc
12 to 22 arc volts
AWS and CSA
V groove or U groove

25. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Duty cycle
If you dont know this check your phone
Insufficient current to melt the wire off cleanly
SMAW - GTAW

26. What happens when the electrode extension is increased?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
The resistace to electrical current flow increases with it. Causing the electrode to heat
Pressure vessels and the piping industry
20 to 200 times per second

27. What does voltage do in an electrical circuit?
1/4 inch to 1/2 inch
Speed of the feed motor and - starting / stopping electrode feed
Voltage is the force that overcomes resistance to allow amperage flow
Penetration and burn - off rate of the electrode

28. Give a brief description of the GMAW process
Duty cycle
20 to 200 times per second
Welding process that joins metals by heating them with an electric arc
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

29. What 2 controls are found on a GMAW set- up?
Pressure - The rate of flow of a shielding gas
When the filler wire is in direct contract with the base metal
These terms are quite restrictive and often technically incorrect
Wire feed speed - Voltage control

30. What does the wire feeder control?
Constant voltage (CV)
Speed of the feed motor and - starting / stopping electrode feed
20 to 200 times per second
To prevent drawing of liquid CO2 (Carbon Dioxide)

31. What does a flowmeter do and what does it measure?
1/4 inch to 1/2 inch
Spatter problems and poor weld appearance
Constant voltage (CV)
Controls the rate of flow of a shielding gas to the gun nozzle

32. List several industries that would use GMAW
Pressure vessels and the piping industry
These terms are quite restrictive and often technically incorrect
(DCEP) Direct Current Electrode Positive or Reverse polarity
Motor driven generators - Transformer rectifiers - and Inverter designs

33. Why is globular transfer generally avoided with GMAW?
Spatter problems and poor weld appearance
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Constant- speed wire feeders and Voltage- sennsing wire feeders
Pressure vessels and the piping industry

34. What are the 2 types of wire feeders available?
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
Constant- speed wire feeders and Voltage- sennsing wire feeders
Wire feed speed
Dry ice can form within the flow control openings and cause blockage of shielding gas

35. What is the preferred drive roll design for solid wires?
(DCEP) Direct Current Electrode Positive or Reverse polarity
DCEP (Direct Current Electrode Positive) Reverse Polarity
V groove or U groove
SMAW - GTAW

36. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
20 to 200 times per second
...
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

37. When is the metal transferred with short circuit transfer?
Reducing the gas source pressure to a constant working pressure
When the filler wire is in direct contract with the base metal
If you dont know this check your phone
...

38. What processes are constant current (CC) power sources designed to be used with?
SMAW - GTAW
Generally not as accurate
These terms are quite restrictive and often technically incorrect
Penetration and burn - off rate of the electrode

39. What controls the wire speed on a voltage sensing wire feeder?
The time rate of response for the current rise and fall
Generally not as accurate
Spatter problems and poor weld appearance
The Arc voltage

40. What is the main purpose of 'slope'?
To limit the short circuiting current so that spatter is reduced
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Short- circuiting transfer - Globular transfer - Spray transfer
If you dont know this check your phone

41. List the basic equipment requirements for the GMAW process
3
Generally not as accurate
To prevent leakage - Carbon Dioxide (CO2)
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

42. Why is the term GMAW preferred over MIG or MAG?
Minimum distortion due to low heat input
Wire feed speed
These terms are quite restrictive and often technically incorrect
15 feet (4.5 meters)

43. List the three methods of metal transfer with GMAW
Pressure vessels and the piping industry
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Short- circuiting transfer - Globular transfer - Spray transfer
Flux cored wires

44. Why must CO2 cylinders be used in the vertical position?
Puddle fluidity
These terms are quite restrictive and often technically incorrect
To prevent drawing of liquid CO2 (Carbon Dioxide)
...

45. What is the maximum distance that hard wire can be successfully pushed?
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
Dry ice can form within the flow control openings and cause blockage of shielding gas
15 feet (4.5 meters)

46. 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
National Electrical Manufactures Association
DCEP (Direct Current Electrode Positive) Reverse Polarity
Spatter problems and poor weld appearance

47. What power sources are used with the GMAW Process?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Motor driven generators - Transformer rectifiers - and Inverter designs
V groove or U groove
By there current carrying capacity

48. What is a solenoid valve and what actuates it?
Minimum distortion due to low heat input
Welding process that joins metals by heating them with an electric arc
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

49. With straight polarity where is 2/3 of the arc energy?
1/4 inch to 1/2 inch
Insufficient current to melt the wire off cleanly
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
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?
12 to 22 arc volts
DCEP (Direct Current Electrode Positive) Reverse Polarity
Dry ice can form within the flow control openings and cause blockage of shielding gas
(DCEP) Direct Current Electrode Positive or Reverse polarity