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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?
20 to 200 times per second
If you dont know this check your phone
Wire feed speed
Generally not as accurate

2. Give a description of 'pinch effect'
These terms are quite restrictive and often technically incorrect
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
85%
1/4 inch to 1/2 inch

3. What is the main purpose of 'slope'?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Short- circuiting transfer - Globular transfer - Spray transfer
DCEP (Direct Current Electrode Positive) Reverse Polarity
To limit the short circuiting current so that spatter is reduced

4. What power sources are used with the GMAW Process?
Motor driven generators - Transformer rectifiers - and Inverter designs
Cause flaking - which can clog the liner and contact tube
These terms are quite restrictive and often technically incorrect
To limit the short circuiting current so that spatter is reduced

5. What is another term for electrode holders for GMAW?
To prevent drawing of liquid CO2 (Carbon Dioxide)
Guns
Insufficient current to melt the wire off cleanly
DCEP (Direct Current Electrode Positive) Reverse Polarity

6. What is the key advantage of short circuiting transfer?
These terms are quite restrictive and often technically incorrect
When the filler wire is in direct contract with the base metal
Welding process that joins metals by heating them with an electric arc
Minimum distortion due to low heat input

7. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
SMAW - GTAW
Motor driven generators - Transformer rectifiers - and Inverter designs
Guns
...

8. What 2 controls are found on a GMAW set- up?
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
85%
If you dont know this check your phone

9. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
12 to 22 arc volts
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Higher 26 to 35 arc volts
Minimum distortion due to low heat input

10. What controls the wire speed on a voltage sensing wire feeder?
Pressure vessels and the piping industry
The Arc voltage
15 feet (4.5 meters)
The resistace to electrical current flow increases with it. Causing the electrode to heat

11. What type of power source is commonly used with a voltage sensing wire feeder?
V groove or U groove
Minimum distortion due to low heat input
AWS and CSA
Constant current (CC)

12. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
These terms are quite restrictive and often technically incorrect
Gives arc voltage values to the control system of the feeder
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Aluminum wire

13. Draw a typical volt amp curve for a machine that is designed for GMAW
National Electrical Manufactures Association
Constant voltage (CV)
If you dont know this check your phone
Minimum distortion due to low heat input

14. What type of power source is used with a constant speed wire feeder?
Aluminum wire
Constant voltage (CV)
To prevent drawing of liquid CO2 (Carbon Dioxide)
Pressure - The rate of flow of a shielding gas

15. Give a brief description of the GMAW process
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Reducing the gas source pressure to a constant working pressure
Constant voltage (CV)
Welding process that joins metals by heating them with an electric arc

16. What is an advantage of pulsed arc transfer with GMAW?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
To prevent drawing of liquid CO2 (Carbon Dioxide)
20 to 200 times per second

17. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Flux cored wires
Duty cycle
The resistace to electrical current flow increases with it. Causing the electrode to heat
Insufficient current to melt the wire off cleanly

18. Regulators control_____________ flowmeters SHOW____________.
Pressure - The rate of flow of a shielding gas
Constant- speed wire feeders and Voltage- sennsing wire feeders
Duty cycle
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

19. What wire are knurled drive rolls most commonly used on?
Gas metal arc welding
Speed of the feed motor and - starting / stopping electrode feed
Flux cored wires
Constant voltage (CV)

20. What is the preferred drive roll design for solid wires?
V groove or U groove
Aluminum wire
...
1/4 inch to 1/2 inch

21. A pull type drive system is usually used on what type of material?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Short- circuiting transfer - Globular transfer - Spray transfer
Pressure vessels and the piping industry
Aluminum wire

22. What happens when the electrode extension is increased?
The resistace to electrical current flow increases with it. Causing the electrode to heat
National Electrical Manufactures Association
To limit the short circuiting current so that spatter is reduced
Constant voltage (CV)

23. What is the required arc voltage used for short circuit transfer?
Duty cycle
12 to 22 arc volts
By there current carrying capacity
To prevent drawing of liquid CO2 (Carbon Dioxide)

24. What is the maximum distance that hard wire can be successfully pushed?
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
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
15 feet (4.5 meters)

25. List 3 forms compressed gases may be supplied for welding
5.8 to 12.5 L/min
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Cause flaking - which can clog the liner and contact tube
The resistace to electrical current flow increases with it. Causing the electrode to heat

26. List several industries that would use GMAW
Pressure vessels and the piping industry
Cause flaking - which can clog the liner and contact tube
V groove or U groove
85%

27. Why is the term GMAW preferred over MIG or MAG?
The negative side of a welding unit
Penetration and burn - off rate of the electrode
These terms are quite restrictive and often technically incorrect
To prevent leakage - Carbon Dioxide (CO2)

28. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
Insufficient current to melt the wire off cleanly
85%
Higher 26 to 35 arc volts
Cause flaking - which can clog the liner and contact tube

29. How are GMAW guns rated?
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Minimum distortion due to low heat input
By there current carrying capacity
Pressure - The rate of flow of a shielding gas

30. List the basic equipment requirements for the GMAW process
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
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Constant- speed wire feeders and Voltage- sennsing wire feeders
Shielding the molten weld metal from atmospheric contamination

31. In the GMAW process what does voltage control?
AWS and CSA
Puddle fluidity
If you dont know this check your phone
SMAW - GTAW

32. What output on the welding machine is used to rate the duty cycle?
Minutes of elapsed time continually run (out of 10 minutes)
Spatter problems and poor weld appearance
15 feet (4.5 meters)
3

33. List the three methods of metal transfer with GMAW
Gas metal arc welding
Voltage is the force that overcomes resistance to allow amperage flow
Controls the rate of flow of a shielding gas to the gun nozzle
Short- circuiting transfer - Globular transfer - Spray transfer

34. What would be an indication that the drive roll pressure is adjusted correctly?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Higher 26 to 35 arc volts
Pressure vessels and the piping industry
Spatter problems and poor weld appearance

35. Why must CO2 cylinders be used in the vertical position?
Gas metal arc welding
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
To prevent drawing of liquid CO2 (Carbon Dioxide)
Gives arc voltage values to the control system of the feeder

36. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
SMAW - GTAW
(DCEP) Direct Current Electrode Positive or Reverse polarity
The Arc voltage
The time rate of response for the current rise and fall

37. What is the purpose of a regulator and what does it indicate on its gauges?
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
Constant voltage (CV)
Reducing the gas source pressure to a constant working pressure

38. With straight polarity where is 2/3 of the arc energy?
The negative side of a welding unit
Dry ice can form within the flow control openings and cause blockage of shielding gas
Constant voltage (CV)
If you dont know this check your phone

39. What are the 2 types of wire feeders available?
20 to 200 times per second
Constant- speed wire feeders and Voltage- sennsing wire feeders
Wire feeds smoothly (yet will slip should a problem occur in the gun)
To limit the short circuiting current so that spatter is reduced

40. What effect does increasing and decreasing the inductance have on the weld?
The negative side of a welding unit
Constant- speed wire feeders and Voltage- sennsing wire feeders
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Higher 26 to 35 arc volts

41. 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
Gas metal arc welding
National Electrical Manufactures Association
Motor driven generators - Transformer rectifiers - and Inverter designs

42. What is a typical flow rate of CO2 for short circuit transfer?
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Short- circuiting transfer - Globular transfer - Spray transfer
5.8 to 12.5 L/min
If you dont know this check your phone

43. Why is a fiber washer required and what cylinder gas requires it?
...
To prevent leakage - Carbon Dioxide (CO2)
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Guns

44. What is the purpose of the shielding gas used in GMAW?
Shielding the molten weld metal from atmospheric contamination
Motor driven generators - Transformer rectifiers - and Inverter designs
Wire feed speed
Duty cycle

45. Why is globular transfer generally avoided with GMAW?
Spatter problems and poor weld appearance
Controls the rate of flow of a shielding gas to the gun nozzle
5.8 to 12.5 L/min
Generally not as accurate

46. Why is a line heater required when using GMAW?
When the filler wire is in direct contract with the base metal
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
Dry ice can form within the flow control openings and cause blockage of shielding gas
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

47. What 2 organizations designate specifications for GMAW wires?
AWS and CSA
Minutes of elapsed time continually run (out of 10 minutes)
15 feet (4.5 meters)
Wire feeds smoothly (yet will slip should a problem occur in the gun)

48. What is the effect of too much slope?
Puddle fluidity
...
Insufficient current to melt the wire off cleanly
Generally not as accurate

49. What does the abbreviation NEMA stand for?
Puddle fluidity
National Electrical Manufactures Association
If you dont know this check your phone
Constant- speed wire feeders and Voltage- sennsing wire feeders

50. When is the metal transferred with short circuit transfer?
The resistace to electrical current flow increases with it. Causing the electrode to heat
When the filler wire is in direct contract with the base metal
AWS and CSA
To limit the short circuiting current so that spatter is reduced