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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 the basic equipment requirements for the GMAW process
Minutes of elapsed time continually run (out of 10 minutes)
Pressure - The rate of flow of a shielding gas
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Gas metal arc welding

2. What is the recommended electrode stick- out for .035 solid wire?
When the filler wire is in direct contract with the base metal
1/4 inch to 1/2 inch
Penetration and burn - off rate of the electrode
15 feet (4.5 meters)

3. Draw a typical volt amp curve for a machine that is designed for GMAW
National Electrical Manufactures Association
...
Insufficient current to melt the wire off cleanly
If you dont know this check your phone

4. What is the required arc voltage used for short circuit transfer?
85%
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
12 to 22 arc volts
Reducing the gas source pressure to a constant working pressure

5. What does the abbreviation NEMA stand for?
To prevent leakage - Carbon Dioxide (CO2)
Cause flaking - which can clog the liner and contact tube
National Electrical Manufactures Association
Motor driven generators - Transformer rectifiers - and Inverter designs

6. What type of power source is commonly used with a voltage sensing wire feeder?
Voltage is the force that overcomes resistance to allow amperage flow
Gives arc voltage values to the control system of the feeder
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Constant current (CC)

7. What is the maximum distance that hard wire can be successfully pushed?
20 to 200 times per second
Voltage is the force that overcomes resistance to allow amperage flow
15 feet (4.5 meters)
AWS and CSA

8. What is the effect of too much slope?
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Insufficient current to melt the wire off cleanly
If you dont know this check your phone
Penetration and burn - off rate of the electrode

9. Why is the term GMAW preferred over MIG or MAG?
Wire feed speed - Voltage control
These terms are quite restrictive and often technically incorrect
National Electrical Manufactures Association
Pressure vessels and the piping industry

10. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
3
(DCEP) Direct Current Electrode Positive or Reverse polarity
V groove or U groove
Spatter problems and poor weld appearance

11. Give a brief description of the GMAW process
Welding process that joins metals by heating them with an electric arc
The negative side of a welding unit
Pressure vessels and the piping industry
Dry ice can form within the flow control openings and cause blockage of shielding gas

12. Why is globular transfer generally avoided with GMAW?
Spatter problems and poor weld appearance
5.8 to 12.5 L/min
Dry ice can form within the flow control openings and cause blockage of shielding gas
Controls the rate of flow of a shielding gas to the gun nozzle

13. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
...
Higher 26 to 35 arc volts
Spatter problems and poor weld appearance
5.8 to 12.5 L/min

14. What is the purpose of a regulator and what does it indicate on its gauges?
V groove or U groove
Penetration and burn - off rate of the electrode
Reducing the gas source pressure to a constant working pressure
Motor driven generators - Transformer rectifiers - and Inverter designs

15. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
Wire feed speed - Voltage control
Wire feeds smoothly (yet will slip should a problem occur in the gun)
(DCEP) Direct Current Electrode Positive or Reverse polarity
Pressure - The rate of flow of a shielding gas

16. When is the metal transferred with short circuit transfer?
Gas metal arc welding
Pressure - The rate of flow of a shielding gas
When the filler wire is in direct contract with the base metal
By there current carrying capacity

17. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
To limit the short circuiting current so that spatter is reduced
National Electrical Manufactures Association
Gives arc voltage values to the control system of the feeder

18. What power sources are used with 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
Guns
Motor driven generators - Transformer rectifiers - and Inverter designs
Constant voltage (CV)

19. What 2 controls are found on a GMAW set- up?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Wire feed speed - Voltage control
The resistace to electrical current flow increases with it. Causing the electrode to heat
SMAW - GTAW

20. What processes are constant current (CC) power sources designed to be used with?
15 feet (4.5 meters)
Motor driven generators - Transformer rectifiers - and Inverter designs
SMAW - GTAW
Constant voltage (CV)

21. What current and polarity is generally used with GMAW?
These terms are quite restrictive and often technically incorrect
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
DCEP (Direct Current Electrode Positive) Reverse Polarity
Wire feeds smoothly (yet will slip should a problem occur in the gun)

22. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
85%
To prevent drawing of liquid CO2 (Carbon Dioxide)
Gives arc voltage values to the control system of the feeder
Short- circuiting transfer - Globular transfer - Spray transfer

23. How many times per second does short circuiting take place?
20 to 200 times per second
Voltage is the force that overcomes resistance to allow amperage flow
Wire feed speed
Generally not as accurate

24. What output on the welding machine is used to rate the duty cycle?
SMAW - GTAW
Wire feed speed
1/4 inch to 1/2 inch
Minutes of elapsed time continually run (out of 10 minutes)

25. What is the purpose of the shielding gas used in GMAW?
Shielding the molten weld metal from atmospheric contamination
Insufficient current to melt the wire off cleanly
Wire feed speed
5.8 to 12.5 L/min

26. Why must CO2 cylinders be used in the vertical position?
The Arc voltage
Flux cored wires
To prevent drawing of liquid CO2 (Carbon Dioxide)
The time rate of response for the current rise and fall

27. What 2 organizations designate specifications for GMAW wires?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Wire feeds smoothly (yet will slip should a problem occur in the gun)
AWS and CSA
Constant voltage (CV)

28. What is the preferred drive roll design for solid wires?
V groove or U groove
These terms are quite restrictive and often technically incorrect
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

29. Why is a line heater required when using GMAW?
Dry ice can form within the flow control openings and cause blockage of shielding gas
Controls the rate of flow of a shielding gas to the gun nozzle
Gives arc voltage values to the control system of the feeder
Guns

30. A pull type drive system is usually used on what type of material?
Dry ice can form within the flow control openings and cause blockage of shielding gas
Aluminum wire
When the filler wire is in direct contract with the base metal
Duty cycle

31. List 3 forms compressed gases may be supplied for welding
Constant current (CC)
Puddle fluidity
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
If you dont know this check your phone

32. Regulators control_____________ flowmeters SHOW____________.
To prevent drawing of liquid CO2 (Carbon Dioxide)
15 feet (4.5 meters)
Pressure - The rate of flow of a shielding gas
Puddle fluidity

33. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Guns
When the filler wire is in direct contract with the base metal
Duty cycle
If you dont know this check your phone

34. What would be an indication that the drive roll pressure is adjusted correctly?
Wire feed speed
12 to 22 arc volts
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Generally not as accurate

35. What is a typical flow rate of CO2 for short circuit transfer?
Pressure vessels and the piping industry
5.8 to 12.5 L/min
Insufficient current to melt the wire off cleanly
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

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

37. In the GMAW process what does amperage control?
85%
Penetration and burn - off rate of the electrode
Voltage is the force that overcomes resistance to allow amperage flow
If you dont know this check your phone

38. What does the term GMAW identify?
Constant- speed wire feeders and Voltage- sennsing wire feeders
Wire feed speed
Gas metal arc welding
These terms are quite restrictive and often technically incorrect

39. What type of power source is used with a constant speed wire feeder?
Constant voltage (CV)
Welding process that joins metals by heating them with an electric arc
When the filler wire is in direct contract with the base metal
Short- circuiting transfer - Globular transfer - Spray transfer

40. Why is a fiber washer required and what cylinder gas requires it?
To prevent drawing of liquid CO2 (Carbon Dioxide)
The negative side of a welding unit
To prevent leakage - Carbon Dioxide (CO2)
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

41. What controls amperage when using GMAW?
Wire feed speed
Speed of the feed motor and - starting / stopping electrode feed
Constant- speed wire feeders and Voltage- sennsing wire feeders
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

42. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
To prevent leakage - Carbon Dioxide (CO2)
Cause flaking - which can clog the liner and contact tube
By there current carrying capacity

43. What is another term for electrode holders for GMAW?
Welding process that joins metals by heating them with an electric arc
Guns
When the filler wire is in direct contract with the base metal
5.8 to 12.5 L/min

44. What does inductance control?
The time rate of response for the current rise and fall
AWS and CSA
To prevent leakage - Carbon Dioxide (CO2)
These terms are quite restrictive and often technically incorrect

45. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
Minutes of elapsed time continually run (out of 10 minutes)
Shielding the molten weld metal from atmospheric contamination
Generally not as accurate
If you dont know this check your phone

46. List several industries that would use GMAW
Reducing the gas source pressure to a constant working pressure
Pressure vessels and the piping industry
Cause flaking - which can clog the liner and contact tube
1/4 inch to 1/2 inch

47. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
When the filler wire is in direct contract with the base metal
Constant current (CC)
Controls the rate of flow of a shielding gas to the gun nozzle
...

48. List 3 wire drive systems and give a short description of each
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Controls the rate of flow of a shielding gas to the gun nozzle
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
Spatter problems and poor weld appearance

49. What is the main purpose of 'slope'?
Voltage is the force that overcomes resistance to allow amperage flow
To limit the short circuiting current so that spatter is reduced
SMAW - GTAW
15 feet (4.5 meters)

50. Give a description of 'pinch effect'
SMAW - GTAW
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Constant current (CC)
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system