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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 controls amperage when using GMAW?
Shielding the molten weld metal from atmospheric contamination
Wire feed speed
Penetration and burn - off rate of the electrode
The time rate of response for the current rise and fall

2. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Duty cycle
Gives arc voltage values to the control system of the feeder
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Flux cored wires

3. What 2 organizations designate specifications for GMAW wires?
...
SMAW - GTAW
AWS and CSA
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

4. Why is a fiber washer required and what cylinder gas requires it?
DCEP (Direct Current Electrode Positive) Reverse Polarity
The negative side of a welding unit
Constant voltage (CV)
To prevent leakage - Carbon Dioxide (CO2)

5. How many times per second does short circuiting take place?
Reducing the gas source pressure to a constant working pressure
20 to 200 times per second
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Speed of the feed motor and - starting / stopping electrode feed

6. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
Minimum distortion due to low heat input
Duty cycle
If you dont know this check your phone
Gas metal arc welding

7. What is the effect of too much slope?
Pressure - The rate of flow of a shielding gas
Insufficient current to melt the wire off cleanly
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
...

8. What is the preferred drive roll design for solid wires?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
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
V groove or U groove

9. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
The negative side of a welding unit
(DCEP) Direct Current Electrode Positive or Reverse polarity
Welding process that joins metals by heating them with an electric arc
Reducing the gas source pressure to a constant working pressure

10. What is the required arc voltage used for short circuit transfer?
Aluminum wire
12 to 22 arc volts
20 to 200 times per second
Wire feed speed

11. List 3 forms compressed gases may be supplied for welding
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Spatter problems and poor weld appearance
Minutes of elapsed time continually run (out of 10 minutes)
DCEP (Direct Current Electrode Positive) Reverse Polarity

12. What processes are constant current (CC) power sources designed to be used with?
Minimum distortion due to low heat input
SMAW - GTAW
Cause flaking - which can clog the liner and contact tube
Welding process that joins metals by heating them with an electric arc

13. In the GMAW process what does voltage control?
Insufficient current to melt the wire off cleanly
Voltage is the force that overcomes resistance to allow amperage flow
The resistace to electrical current flow increases with it. Causing the electrode to heat
Puddle fluidity

14. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
Generally not as accurate
3
Gas metal arc welding
Puddle fluidity

15. How are GMAW guns rated?
By there current carrying capacity
Pressure vessels and the piping industry
Constant current (CC)
15 feet (4.5 meters)

16. What is the key advantage of short circuiting transfer?
When the filler wire is in direct contract with the base metal
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
Minimum distortion due to low heat input

17. What is the main purpose of 'slope'?
1/4 inch to 1/2 inch
Generally not as accurate
To limit the short circuiting current so that spatter is reduced
5.8 to 12.5 L/min

18. Why must CO2 cylinders be used in the vertical position?
Controls the rate of flow of a shielding gas to the gun nozzle
V groove or U groove
To prevent drawing of liquid CO2 (Carbon Dioxide)
Cause flaking - which can clog the liner and contact tube

19. A pull type drive system is usually used on what type of material?
Aluminum wire
The Arc voltage
If you dont know this check your phone
5.8 to 12.5 L/min

20. Why is a line heater required when using GMAW?
Dry ice can form within the flow control openings and cause blockage of shielding gas
1/4 inch to 1/2 inch
The Arc voltage
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

21. Regulators control_____________ flowmeters SHOW____________.
Constant voltage (CV)
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
Pressure - The rate of flow of a shielding gas
3

22. Why is the term GMAW preferred over MIG or MAG?
Pressure vessels and the piping industry
To prevent drawing of liquid CO2 (Carbon Dioxide)
These terms are quite restrictive and often technically incorrect
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

23. What are the 2 types of wire feeders available?
The negative side of a welding unit
Constant- speed wire feeders and Voltage- sennsing wire feeders
Short- circuiting transfer - Globular transfer - Spray transfer
When the filler wire is in direct contract with the base metal

24. What is the purpose of a regulator and what does it indicate on its gauges?
Spatter problems and poor weld appearance
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Reducing the gas source pressure to a constant working pressure
The time rate of response for the current rise and fall

25. List the three methods of metal transfer with GMAW
Dry ice can form within the flow control openings and cause blockage of shielding gas
Short- circuiting transfer - Globular transfer - Spray transfer
Minimum distortion due to low heat input
Welding process that joins metals by heating them with an electric arc

26. What type of power source is commonly used with a voltage sensing wire feeder?
National Electrical Manufactures Association
Generally not as accurate
Constant current (CC)
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

27. What does the abbreviation NEMA stand for?
Higher 26 to 35 arc volts
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
Duty cycle

28. What wire are knurled drive rolls most commonly used on?
Insufficient current to melt the wire off cleanly
Higher 26 to 35 arc volts
Flux cored wires
Motor driven generators - Transformer rectifiers - and Inverter designs

29. What is the maximum distance that hard wire can be successfully pushed?
3
Welding process that joins metals by heating them with an electric arc
15 feet (4.5 meters)
Cause flaking - which can clog the liner and contact tube

30. List the basic equipment requirements for the GMAW process
National Electrical Manufactures Association
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Gives arc voltage values to the control system of the feeder

31. What is an advantage of pulsed arc transfer with GMAW?
3
By there current carrying capacity
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

32. What is the disadvantage of the gauge preset type of regulator/flowmeter?
To prevent leakage - Carbon Dioxide (CO2)
Minutes of elapsed time continually run (out of 10 minutes)
Generally not as accurate
12 to 22 arc volts

33. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
V groove or U groove
...
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
AWS and CSA

34. What effect does increasing and decreasing the inductance have on the weld?
Pressure vessels and the piping industry
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
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

35. What current and polarity is generally used with GMAW?
...
Dry ice can form within the flow control openings and cause blockage of shielding gas
DCEP (Direct Current Electrode Positive) Reverse Polarity
Guns

36. What does the term GMAW identify?
85%
Guns
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
Gas metal arc welding

37. 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
Dry ice can form within the flow control openings and cause blockage of shielding gas
Minutes of elapsed time continually run (out of 10 minutes)

38. List 3 wire drive systems and give a short description of each
To prevent leakage - Carbon Dioxide (CO2)
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
Penetration and burn - off rate of the electrode
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

39. What is another term for electrode holders for GMAW?
Voltage is the force that overcomes resistance to allow amperage flow
Guns
National Electrical Manufactures Association
Spatter problems and poor weld appearance

40. What would be an indication that the drive roll pressure is adjusted correctly?
15 feet (4.5 meters)
Welding process that joins metals by heating them with an electric arc
Generally not as accurate
Wire feeds smoothly (yet will slip should a problem occur in the gun)

41. What does the wire feeder control?
(DCEP) Direct Current Electrode Positive or Reverse polarity
Guns
Dry ice can form within the flow control openings and cause blockage of shielding gas
Speed of the feed motor and - starting / stopping electrode feed

42. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Penetration and burn - off rate of the electrode
Controls the rate of flow of a shielding gas to the gun nozzle
When the filler wire is in direct contract with the base metal
Duty cycle

43. What does voltage do in an electrical circuit?
Constant current (CC)
Voltage is the force that overcomes resistance to allow amperage flow
Gas metal arc welding
Minutes of elapsed time continually run (out of 10 minutes)

44. What is the purpose of the shielding gas used in GMAW?
12 to 22 arc volts
Dry ice can form within the flow control openings and cause blockage of shielding gas
Voltage is the force that overcomes resistance to allow amperage flow
Shielding the molten weld metal from atmospheric contamination

45. What type of power source is used with a constant speed wire feeder?
Minimum distortion due to low heat input
Constant voltage (CV)
SMAW - GTAW
5.8 to 12.5 L/min

46. Give a description of 'pinch effect'
20 to 200 times per second
Guns
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
...

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

48. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
Duty cycle
85%
Speed of the feed motor and - starting / stopping electrode feed
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

49. When is the metal transferred with short circuit transfer?
Cause flaking - which can clog the liner and contact tube
When the filler wire is in direct contract with the base metal
Constant- speed wire feeders and Voltage- sennsing wire feeders
Generally not as accurate

50. What is a solenoid valve and what actuates it?
AWS and CSA
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
National Electrical Manufactures Association
Penetration and burn - off rate of the electrode