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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.
Don't refresh. All questions and answers are randomly picked and ordered every time you load a test.

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. Why is globular transfer generally avoided with GMAW?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Constant current (CC)
Short- circuiting transfer - Globular transfer - Spray transfer
Spatter problems and poor weld appearance

2. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
...
The resistace to electrical current flow increases with it. Causing the electrode to heat
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

3. Why is a fiber washer required and what cylinder gas requires it?
Pressure - The rate of flow of a shielding gas
20 to 200 times per second
To prevent leakage - Carbon Dioxide (CO2)
Minutes of elapsed time continually run (out of 10 minutes)

4. In the GMAW process what does amperage control?
Voltage is the force that overcomes resistance to allow amperage flow
Generally not as accurate
Minimum distortion due to low heat input
Penetration and burn - off rate of the electrode

5. List the basic equipment requirements for the GMAW process
(DCEP) Direct Current Electrode Positive or Reverse polarity
AWS and CSA
5.8 to 12.5 L/min
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

6. What is the maximum distance that hard wire can be successfully pushed?
15 feet (4.5 meters)
Cause flaking - which can clog the liner and contact tube
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
3

7. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Duty cycle
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Constant- speed wire feeders and Voltage- sennsing wire feeders
Gives arc voltage values to the control system of the feeder

8. What processes are constant current (CC) power sources designed to be used with?
SMAW - GTAW
Welding process that joins metals by heating them with an electric arc
3
Pressure - The rate of flow of a shielding gas

9. What is an advantage of pulsed arc transfer with GMAW?
5.8 to 12.5 L/min
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
The time rate of response for the current rise and fall
Controls the rate of flow of a shielding gas to the gun nozzle

10. What type of power source is used with a constant speed wire feeder?
Constant voltage (CV)
National Electrical Manufactures Association
Minimum distortion due to low heat input
1/4 inch to 1/2 inch

11. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
3
Generally not as accurate
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

12. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
By there current carrying capacity
V groove or U groove
Gives arc voltage values to the control system of the feeder

13. Draw a typical volt amp curve for a machine that is designed for GMAW
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
12 to 22 arc volts
Speed of the feed motor and - starting / stopping electrode feed

14. What does the wire feeder control?
The negative side of a welding unit
Aluminum wire
The time rate of response for the current rise and fall
Speed of the feed motor and - starting / stopping electrode feed

15. With straight polarity where is 2/3 of the arc energy?
Shielding the molten weld metal from atmospheric contamination
Constant- speed wire feeders and Voltage- sennsing wire feeders
The negative side of a welding unit
Duty cycle

16. List several industries that would use GMAW
Pressure vessels and the piping industry
Minutes of elapsed time continually run (out of 10 minutes)
15 feet (4.5 meters)
Insufficient current to melt the wire off cleanly

17. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Wire feed speed
Gas metal arc welding
If you dont know this check your phone
Higher 26 to 35 arc volts

18. List the factors that determine the mode of metal transfer
85%
Minutes of elapsed time continually run (out of 10 minutes)
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

19. List the three methods of metal transfer with GMAW
Voltage is the force that overcomes resistance to allow amperage flow
By there current carrying capacity
Short- circuiting transfer - Globular transfer - Spray transfer
Constant- speed wire feeders and Voltage- sennsing wire feeders

20. What type of power source is commonly used with a voltage sensing wire feeder?
Constant current (CC)
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
By there current carrying capacity

21. What is the main purpose of 'slope'?
By there current carrying capacity
To limit the short circuiting current so that spatter is reduced
The negative side of a welding unit
Speed of the feed motor and - starting / stopping electrode feed

22. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
3
Constant current (CC)
Flux cored wires
Pressure vessels and the piping industry

23. What current and polarity is generally used with GMAW?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Minutes of elapsed time continually run (out of 10 minutes)
SMAW - GTAW
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

24. How are GMAW guns rated?
Welding process that joins metals by heating them with an electric arc
By there current carrying capacity
Spatter problems and poor weld appearance
Constant voltage (CV)

25. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
The time rate of response for the current rise and fall
85%
Shielding the molten weld metal from atmospheric contamination
Penetration and burn - off rate of the electrode

26. Why is the term GMAW preferred over MIG or MAG?
Constant- speed wire feeders and Voltage- sennsing wire feeders
1/4 inch to 1/2 inch
When the filler wire is in direct contract with the base metal
These terms are quite restrictive and often technically incorrect

27. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
The resistace to electrical current flow increases with it. Causing the electrode to heat
Flux cored wires
(DCEP) Direct Current Electrode Positive or Reverse polarity

28. What power sources are used with the GMAW Process?
To prevent drawing of liquid CO2 (Carbon Dioxide)
DCEP (Direct Current Electrode Positive) Reverse Polarity
The Arc voltage
Motor driven generators - Transformer rectifiers - and Inverter designs

29. What does inductance control?
Constant current (CC)
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
The time rate of response for the current rise and fall
Gives arc voltage values to the control system of the feeder

30. What is the key advantage of short circuiting transfer?
The Arc voltage
(DCEP) Direct Current Electrode Positive or Reverse polarity
Minimum distortion due to low heat input
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

31. What 2 controls are found on a GMAW set- up?
The time rate of response for the current rise and fall
Wire feed speed - Voltage control
Spatter problems and poor weld appearance
Constant current (CC)

32. A pull type drive system is usually used on what type of material?
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
To prevent leakage - Carbon Dioxide (CO2)
Aluminum wire

33. What is the purpose of a regulator and what does it indicate on its gauges?
The negative side of a welding unit
Short- circuiting transfer - Globular transfer - Spray transfer
Minimum distortion due to low heat input
Reducing the gas source pressure to a constant working pressure

34. Why is a line heater required when using GMAW?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Dry ice can form within the flow control openings and cause blockage of shielding gas
Higher 26 to 35 arc volts
SMAW - GTAW

35. What is the effect of too much slope?
Voltage is the force that overcomes resistance to allow amperage flow
Insufficient current to melt the wire off cleanly
Spatter problems and poor weld appearance
Constant- speed wire feeders and Voltage- sennsing wire feeders

36. 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
Penetration and burn - off rate of the electrode
V groove or U groove
Wire feeds smoothly (yet will slip should a problem occur in the gun)

37. In the GMAW process what does voltage control?
Pressure - The rate of flow of a shielding gas
Puddle fluidity
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
12 to 22 arc volts

38. Give a brief description of the GMAW process
Generally not as accurate
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
By there current carrying capacity
Welding process that joins metals by heating them with an electric arc

39. Regulators control_____________ flowmeters SHOW____________.
...
Pressure - The rate of flow of a shielding gas
Insufficient current to melt the wire off cleanly
20 to 200 times per second

40. What 2 organizations designate specifications for GMAW wires?
Spatter problems and poor weld appearance
AWS and CSA
Speed of the feed motor and - starting / stopping electrode feed
Gives arc voltage values to the control system of the feeder

41. What does voltage do in an electrical circuit?
Voltage is the force that overcomes resistance to allow amperage flow
Gives arc voltage values to the control system of the feeder
To prevent drawing of liquid CO2 (Carbon Dioxide)
Controls the rate of flow of a shielding gas to the gun nozzle

42. What is the purpose of the shielding gas used in GMAW?
Guns
Minimum distortion due to low heat input
Shielding the molten weld metal from atmospheric contamination
When the filler wire is in direct contract with the base metal

43. List 3 forms compressed gases may be supplied for welding
Constant voltage (CV)
By there current carrying capacity
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

44. What controls the wire speed on a voltage sensing wire feeder?
If you dont know this check your phone
The Arc voltage
Pressure vessels and the piping industry
Generally not as accurate

45. What does the abbreviation NEMA stand for?
National Electrical Manufactures Association
AWS and CSA
20 to 200 times per second
Penetration and burn - off rate of the electrode

46. What are the 2 types of wire feeders available?
Constant voltage (CV)
Constant- speed wire feeders and Voltage- sennsing wire feeders
To prevent drawing of liquid CO2 (Carbon Dioxide)
Aluminum wire

47. 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
Aluminum wire
AWS and CSA
National Electrical Manufactures Association

48. What does a flowmeter do and what does it measure?
Penetration and burn - off rate of the electrode
...
If you dont know this check your phone
Controls the rate of flow of a shielding gas to the gun nozzle

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

50. How many times per second does short circuiting take place?
SMAW - GTAW
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Dry ice can form within the flow control openings and cause blockage of shielding gas
20 to 200 times per second