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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 3 forms compressed gases may be supplied for welding
Minimum distortion due to low heat input
Minutes of elapsed time continually run (out of 10 minutes)
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
DCEP (Direct Current Electrode Positive) Reverse Polarity

2. What is the required arc voltage used for short circuit transfer?
3
12 to 22 arc volts
Cause flaking - which can clog the liner and contact tube
Reducing the gas source pressure to a constant working pressure

3. What 2 organizations designate specifications for GMAW wires?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
If you dont know this check your phone
12 to 22 arc volts
AWS and CSA

4. List several industries that would use GMAW
Higher 26 to 35 arc volts
Pressure vessels and the piping industry
Minimum distortion due to low heat input
Gas metal arc welding

5. What does the abbreviation NEMA stand for?
Penetration and burn - off rate of the electrode
Guns
Speed of the feed motor and - starting / stopping electrode feed
National Electrical Manufactures Association

6. What is the recommended electrode stick- out for .035 solid wire?
1/4 inch to 1/2 inch
Gas metal arc welding
Pressure vessels and the piping industry
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

7. What is the preferred drive roll design for solid wires?
Pressure - The rate of flow of a shielding gas
V groove or U groove
National Electrical Manufactures Association
Controls the rate of flow of a shielding gas to the gun nozzle

8. What current and polarity is generally used with GMAW?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Shielding the molten weld metal from atmospheric contamination
The resistace to electrical current flow increases with it. Causing the electrode to heat

9. Give a description of 'pinch effect'
Welding process that joins metals by heating them with an electric arc
Gives arc voltage values to the control system of the feeder
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
V groove or U groove

10. What controls amperage when using GMAW?
To prevent leakage - Carbon Dioxide (CO2)
The time rate of response for the current rise and fall
Wire feed speed
...

11. What power sources are used with the GMAW Process?
Higher 26 to 35 arc volts
Motor driven generators - Transformer rectifiers - and Inverter designs
Gives arc voltage values to the control system of the feeder
The negative side of a welding unit

12. List 3 wire drive systems and give a short description of each
Flux cored wires
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
1/4 inch to 1/2 inch
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

13. Why must CO2 cylinders be used in the vertical position?
Penetration and burn - off rate of the electrode
If you dont know this check your phone
Dry ice can form within the flow control openings and cause blockage of shielding gas
To prevent drawing of liquid CO2 (Carbon Dioxide)

14. What is the purpose of the shielding gas used in GMAW?
5.8 to 12.5 L/min
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Shielding the molten weld metal from atmospheric contamination
Short- circuiting transfer - Globular transfer - Spray transfer

15. What does the wire feeder control?
Voltage is the force that overcomes resistance to allow amperage flow
V groove or U groove
Constant- speed wire feeders and Voltage- sennsing wire feeders
Speed of the feed motor and - starting / stopping electrode feed

16. List the factors that determine the mode of metal transfer
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
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
These terms are quite restrictive and often technically incorrect
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

17. Why is a fiber washer required and what cylinder gas requires it?
To prevent leakage - Carbon Dioxide (CO2)
3
Dry ice can form within the flow control openings and cause blockage of shielding gas
If you dont know this check your phone

18. What is an advantage of pulsed arc transfer with GMAW?
National Electrical Manufactures Association
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
SMAW - GTAW

19. What is the key advantage of short circuiting transfer?
Cause flaking - which can clog the liner and contact tube
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
Minimum distortion due to low heat input
Dry ice can form within the flow control openings and cause blockage of shielding gas

20. In the GMAW process what does amperage control?
To prevent drawing of liquid CO2 (Carbon Dioxide)
Constant- speed wire feeders and Voltage- sennsing wire feeders
Voltage is the force that overcomes resistance to allow amperage flow
Penetration and burn - off rate of the electrode

21. What type of power source is used with a constant speed wire feeder?
Constant voltage (CV)
Higher 26 to 35 arc volts
Voltage is the force that overcomes resistance to allow amperage flow
To limit the short circuiting current so that spatter is reduced

22. Give a brief description of the GMAW process
Puddle fluidity
Welding process that joins metals by heating them with an electric arc
Dry ice can form within the flow control openings and cause blockage of shielding gas
12 to 22 arc volts

23. With straight polarity where is 2/3 of the arc energy?
When the filler wire is in direct contract with the base metal
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
The negative side of a welding unit
Gives arc voltage values to the control system of the feeder

24. What are the 2 types of wire feeders available?
AWS and CSA
Voltage is the force that overcomes resistance to allow amperage flow
Constant- speed wire feeders and Voltage- sennsing wire feeders
If you dont know this check your phone

25. What type of power source is commonly used with a voltage sensing wire feeder?
Controls the rate of flow of a shielding gas to the gun nozzle
Constant current (CC)
Aluminum wire
Minutes of elapsed time continually run (out of 10 minutes)

26. Draw a typical volt amp curve for a machine that is designed for GMAW
Higher 26 to 35 arc volts
Generally not as accurate
If you dont know this check your phone
Minimum distortion due to low heat input

27. Why is the term GMAW preferred over MIG or MAG?
Higher 26 to 35 arc volts
If you dont know this check your phone
These terms are quite restrictive and often technically incorrect
The resistace to electrical current flow increases with it. Causing the electrode to heat

28. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
...
Dry ice can form within the flow control openings and cause blockage of shielding gas
3
Constant current (CC)

29. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
Controls the rate of flow of a shielding gas to the gun nozzle
The negative side of a welding unit
To prevent leakage - Carbon Dioxide (CO2)
85%

30. What 2 controls are found on a GMAW set- up?
Reducing the gas source pressure to a constant working pressure
Wire feed speed - Voltage control
To prevent drawing of liquid CO2 (Carbon Dioxide)
To limit the short circuiting current so that spatter is reduced

31. How many times per second does short circuiting take place?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
20 to 200 times per second
3
To limit the short circuiting current so that spatter is reduced

32. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
3
Reducing the gas source pressure to a constant working pressure
To prevent drawing of liquid CO2 (Carbon Dioxide)
When the filler wire is in direct contract with the base metal

33. What is another term for electrode holders for GMAW?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Gas metal arc welding
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Guns

34. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Short- circuiting transfer - Globular transfer - Spray transfer
Generally not as accurate
Constant- speed wire feeders and Voltage- sennsing wire feeders
Duty cycle

35. What is the purpose of a regulator and what does it indicate on its gauges?
Reducing the gas source pressure to a constant working pressure
Aluminum wire
Penetration and burn - off rate of the electrode
The Arc voltage

36. What does the term GMAW identify?
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
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

37. What happens when the electrode extension is increased?
The resistace to electrical current flow increases with it. Causing the electrode to heat
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
Generally not as accurate

38. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Generally not as accurate
Minutes of elapsed time continually run (out of 10 minutes)
Aluminum wire
Spatter problems and poor weld appearance

39. What is the effect of too much slope?
To limit the short circuiting current so that spatter is reduced
Insufficient current to melt the wire off cleanly
Gives arc voltage values to the control system of the feeder
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

40. 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
If you dont know this check your phone
Higher 26 to 35 arc volts
V groove or U groove

41. List the three methods of metal transfer with GMAW
These terms are quite restrictive and often technically incorrect
V groove or U groove
Short- circuiting transfer - Globular transfer - Spray transfer
The Arc voltage

42. What would be an indication that the drive roll pressure is adjusted correctly?
To prevent drawing of liquid CO2 (Carbon Dioxide)
Wire feeds smoothly (yet will slip should a problem occur in the gun)
1/4 inch to 1/2 inch
3

43. What does a flowmeter do and what does it measure?
The resistace to electrical current flow increases with it. Causing the electrode to heat
Wire feed speed - Voltage control
Controls the rate of flow of a shielding gas to the gun nozzle
Dry ice can form within the flow control openings and cause blockage of shielding gas

44. What effect does increasing and decreasing the inductance have on the weld?
20 to 200 times per second
Welding process that joins metals by heating them with an electric arc
Aluminum wire
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

45. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
The Arc voltage
(DCEP) Direct Current Electrode Positive or Reverse polarity
Cause flaking - which can clog the liner and contact tube
If you dont know this check your phone

46. What does inductance control?
The time rate of response for the current rise and fall
Shielding the molten weld metal from atmospheric contamination
3
Constant- speed wire feeders and Voltage- sennsing wire feeders

47. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Constant- speed wire feeders and Voltage- sennsing wire feeders
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
Gives arc voltage values to the control system of the feeder

48. When is the metal transferred with short circuit transfer?
1/4 inch to 1/2 inch
When the filler wire is in direct contract with the base metal
Insufficient current to melt the wire off cleanly
Puddle fluidity

49. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Guns
Constant voltage (CV)
Higher 26 to 35 arc volts
If you dont know this check your phone

50. What does voltage do in an electrical circuit?
Voltage is the force that overcomes resistance to allow amperage flow
...
15 feet (4.5 meters)
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld