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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. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
Guns
3
Gives arc voltage values to the control system of the feeder
Minimum distortion due to low heat input

2. List 3 forms compressed gases may be supplied for welding
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
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Puddle fluidity

3. 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
Motor driven generators - Transformer rectifiers - and Inverter designs
The resistace to electrical current flow increases with it. Causing the electrode to heat

4. Regulators control_____________ flowmeters SHOW____________.
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Pressure - The rate of flow of a shielding gas
Constant voltage (CV)
Puddle fluidity

5. Why must CO2 cylinders be used in the vertical position?
Minimum distortion due to low heat input
...
To prevent drawing of liquid CO2 (Carbon Dioxide)
These terms are quite restrictive and often technically incorrect

6. What type of power source is used with a constant speed wire feeder?
Constant voltage (CV)
Reducing the gas source pressure to a constant working pressure
Aluminum wire
Guns

7. What is the effect of too much slope?
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
To limit the short circuiting current so that spatter is reduced
Insufficient current to melt the wire off cleanly
Minimum distortion due to low heat input

8. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
Insufficient current to melt the wire off cleanly
20 to 200 times per second
...
Higher 26 to 35 arc volts

9. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Aluminum wire
Wire feed speed - Voltage control
Higher 26 to 35 arc volts
85%

10. What does a flowmeter do and what does it measure?
Controls the rate of flow of a shielding gas to the gun nozzle
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Constant- speed wire feeders and Voltage- sennsing wire feeders
20 to 200 times per second

11. What is another term for electrode holders for GMAW?
Guns
Flux cored wires
These terms are quite restrictive and often technically incorrect
Pressure vessels and the piping industry

12. What does the term GMAW identify?
Gas metal arc welding
The negative side of a welding unit
The Arc voltage
Guns

13. What does the abbreviation NEMA stand for?
V groove or U groove
National Electrical Manufactures Association
The negative side of a welding unit
To prevent drawing of liquid CO2 (Carbon Dioxide)

14. What wire are knurled drive rolls most commonly used on?
Spatter problems and poor weld appearance
Flux cored wires
5.8 to 12.5 L/min
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15. What controls the wire speed on a voltage sensing wire feeder?
If you dont know this check your phone
Wire feeds smoothly (yet will slip should a problem occur in the gun)
The Arc voltage
DCEP (Direct Current Electrode Positive) Reverse Polarity

16. A pull type drive system is usually used on what type of material?
Aluminum wire
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
Voltage is the force that overcomes resistance to allow amperage flow

17. What 2 controls are found on a GMAW set- up?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Wire feed speed - Voltage control
Motor driven generators - Transformer rectifiers - and Inverter designs
V groove or U groove

18. What is the disadvantage of the gauge preset type of regulator/flowmeter?
15 feet (4.5 meters)
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Duty cycle
Generally not as accurate

19. What is the purpose of a regulator and what does it indicate on its gauges?
Minutes of elapsed time continually run (out of 10 minutes)
Pressure vessels and the piping industry
20 to 200 times per second
Reducing the gas source pressure to a constant working pressure

20. What controls amperage when using GMAW?
Wire feed speed
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Minutes of elapsed time continually run (out of 10 minutes)
Shielding the molten weld metal from atmospheric contamination

21. 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)
Speed of the feed motor and - starting / stopping electrode feed
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Reducing the gas source pressure to a constant working pressure

22. What is an advantage of pulsed arc transfer with GMAW?
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
Duty cycle
The negative side of a welding unit

23. What is the recommended electrode stick- out for .035 solid wire?
To prevent drawing of liquid CO2 (Carbon Dioxide)
...
1/4 inch to 1/2 inch
When the filler wire is in direct contract with the base metal

24. What happens when the electrode extension is increased?
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
The resistace to electrical current flow increases with it. Causing the electrode to heat
Pressure vessels and the piping industry

25. In the GMAW process what does voltage control?
To prevent drawing of liquid CO2 (Carbon Dioxide)
The Arc voltage
Puddle fluidity
Minimum distortion due to low heat input

26. How are GMAW guns rated?
By there current carrying capacity
Wire feeds smoothly (yet will slip should a problem occur in the gun)
...
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

27. What output on the welding machine is used to rate the duty cycle?
Minutes of elapsed time continually run (out of 10 minutes)
These terms are quite restrictive and often technically incorrect
The Arc voltage
1/4 inch to 1/2 inch

28. Draw a typical volt amp curve for a machine that is designed for GMAW
Controls the rate of flow of a shielding gas to the gun nozzle
12 to 22 arc volts
Cause flaking - which can clog the liner and contact tube
If you dont know this check your phone

29. What is the purpose of the shielding gas used in GMAW?
12 to 22 arc volts
Shielding the molten weld metal from atmospheric contamination
Pressure - The rate of flow of a shielding gas
When the filler wire is in direct contract with the base metal

30. What is a typical flow rate of CO2 for short circuit transfer?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
15 feet (4.5 meters)
5.8 to 12.5 L/min

31. What is the key advantage of short circuiting transfer?
Puddle fluidity
Minimum distortion due to low heat input
AWS and CSA
12 to 22 arc volts

32. What does voltage do in an electrical circuit?
Voltage is the force that overcomes resistance to allow amperage flow
5.8 to 12.5 L/min
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Welding process that joins metals by heating them with an electric arc

33. With straight polarity where is 2/3 of the arc energy?
Motor driven generators - Transformer rectifiers - and Inverter designs
The negative side of a welding unit
Generally not as accurate
Wire feeds smoothly (yet will slip should a problem occur in the gun)

34. Why is the term GMAW preferred over MIG or MAG?
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
V groove or U groove
Voltage is the force that overcomes resistance to allow amperage flow

35. What is the preferred drive roll design for solid wires?
V groove or U groove
20 to 200 times per second
Insufficient current to melt the wire off cleanly
Wire feed speed

36. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
If you dont know this check your phone
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Dry ice can form within the flow control openings and cause blockage of shielding gas
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

37. In the GMAW process what does amperage control?
Dry ice can form within the flow control openings and cause blockage of shielding gas
Penetration and burn - off rate of the electrode
Shielding the molten weld metal from atmospheric contamination
Puddle fluidity

38. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Cause flaking - which can clog the liner and contact tube
3
The time rate of response for the current rise and fall
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

39. What current and polarity is generally used with GMAW?
Pressure - The rate of flow of a shielding gas
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
These terms are quite restrictive and often technically incorrect

40. Why is a line heater required when using GMAW?
Dry ice can form within the flow control openings and cause blockage of shielding gas
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
12 to 22 arc volts
Spatter problems and poor weld appearance

41. Why is globular transfer generally avoided with GMAW?
If you dont know this check your phone
Constant current (CC)
Constant- speed wire feeders and Voltage- sennsing wire feeders
Spatter problems and poor weld appearance

42. 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
If you dont know this check your phone
SMAW - GTAW

43. What are the 2 types of wire feeders available?
Voltage is the force that overcomes resistance to allow amperage flow
To prevent leakage - Carbon Dioxide (CO2)
Minimum distortion due to low heat input
Constant- speed wire feeders and Voltage- sennsing wire feeders

44. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
Speed of the feed motor and - starting / stopping electrode feed
(DCEP) Direct Current Electrode Positive or Reverse polarity
Pressure - The rate of flow of a shielding gas
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

45. What is the main purpose of 'slope'?
Constant current (CC)
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
To limit the short circuiting current so that spatter is reduced
Flux cored wires

46. What does inductance control?
The time rate of response for the current rise and fall
20 to 200 times per second
Generally not as accurate
Controls the rate of flow of a shielding gas to the gun nozzle

47. Give a description of 'pinch effect'
Minutes of elapsed time continually run (out of 10 minutes)
Shielding the molten weld metal from atmospheric contamination
Puddle fluidity
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

48. What does the wire feeder control?
Speed of the feed motor and - starting / stopping electrode feed
DCEP (Direct Current Electrode Positive) Reverse Polarity
15 feet (4.5 meters)
If you dont know this check your phone

49. What type of power source is commonly used with a voltage sensing wire feeder?
Wire feed speed
Wire feed speed - Voltage control
Speed of the feed motor and - starting / stopping electrode feed
Constant current (CC)

50. What processes are constant current (CC) power sources designed to be used with?
Welding process that joins metals by heating them with an electric arc
SMAW - GTAW
Short- circuiting transfer - Globular transfer - Spray transfer
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground