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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.
Don't refresh. All questions and answers are randomly picked and ordered every time you load a test.

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. Why must CO2 cylinders be used in the vertical position?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
SMAW - GTAW
To prevent drawing of liquid CO2 (Carbon Dioxide)
Reducing the gas source pressure to a constant working pressure

2. List 3 forms compressed gases may be supplied for welding
Wire feed speed - Voltage control
Wire feed speed
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
(DCEP) Direct Current Electrode Positive or Reverse polarity

3. List the three methods of metal transfer with GMAW
Short- circuiting transfer - Globular transfer - Spray transfer
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Wire feed speed
5.8 to 12.5 L/min

4. What type of power source is commonly used with a voltage sensing wire feeder?
Constant current (CC)
Gives arc voltage values to the control system of the feeder
Duty cycle
Aluminum wire

5. Why is the term GMAW preferred over MIG or MAG?
These terms are quite restrictive and often technically incorrect
Pressure - The rate of flow of a shielding gas
85%
The resistace to electrical current flow increases with it. Causing the electrode to heat

6. What controls amperage when using GMAW?
Penetration and burn - off rate of the electrode
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
Constant current (CC)

7. List 3 wire drive systems and give a short description of each
Minimum distortion due to low heat input
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
Generally not as accurate

8. List the factors that determine the mode of metal transfer
Shielding the molten weld metal from atmospheric contamination
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
To prevent drawing of liquid CO2 (Carbon Dioxide)

9. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Pressure - The rate of flow of a shielding gas
Cause flaking - which can clog the liner and contact tube
Constant current (CC)
Voltage is the force that overcomes resistance to allow amperage flow

10. List the basic equipment requirements for the GMAW process
3
Penetration and burn - off rate of the electrode
Motor driven generators - Transformer rectifiers - and Inverter designs
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

11. What is the main purpose of 'slope'?
Dry ice can form within the flow control openings and cause blockage of shielding gas
The negative side of a welding unit
Voltage is the force that overcomes resistance to allow amperage flow
To limit the short circuiting current so that spatter is reduced

12. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
Flux cored wires
The Arc voltage
If you dont know this check your phone
Puddle fluidity

13. What type of power source is used with a constant speed wire feeder?
Constant voltage (CV)
Aluminum wire
Generally not as accurate
Dry ice can form within the flow control openings and cause blockage of shielding gas

14. What happens when the electrode extension is increased?
The resistace to electrical current flow increases with it. Causing the electrode to heat
Wire feed speed
The Arc voltage
Voltage is the force that overcomes resistance to allow amperage flow

15. Why is globular transfer generally avoided with GMAW?
Minimum distortion due to low heat input
Spatter problems and poor weld appearance
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Gives arc voltage values to the control system of the feeder

16. A pull type drive system is usually used on what type of material?
Aluminum wire
AWS and CSA
Controls the rate of flow of a shielding gas to the gun nozzle
Minimum distortion due to low heat input

17. What is the preferred drive roll design for solid wires?
V groove or U groove
20 to 200 times per second
1/4 inch to 1/2 inch
Puddle fluidity

18. What is another term for electrode holders for GMAW?
Pressure vessels and the piping industry
Guns
Controls the rate of flow of a shielding gas to the gun nozzle
AWS and CSA

19. What does inductance control?
...
Higher 26 to 35 arc volts
Motor driven generators - Transformer rectifiers - and Inverter designs
The time rate of response for the current rise and fall

20. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
Constant- speed wire feeders and Voltage- sennsing wire feeders
By there current carrying capacity
85%
Dry ice can form within the flow control openings and cause blockage of shielding gas

21. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Duty cycle
Constant current (CC)
To prevent drawing of liquid CO2 (Carbon Dioxide)
Penetration and burn - off rate of the electrode

22. What is the maximum distance that hard wire can be successfully pushed?
15 feet (4.5 meters)
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
Flux cored wires
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

23. What is a solenoid valve and what actuates it?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
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
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

24. What current and polarity is generally used with GMAW?
If you dont know this check your phone
DCEP (Direct Current Electrode Positive) Reverse Polarity
Welding process that joins metals by heating them with an electric arc
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

25. What is the key advantage of short circuiting transfer?
Minimum distortion due to low heat input
To prevent drawing of liquid CO2 (Carbon Dioxide)
Higher 26 to 35 arc volts
Short- circuiting transfer - Globular transfer - Spray transfer

26. In the GMAW process what does voltage control?
Puddle fluidity
Welding process that joins metals by heating them with an electric arc
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

27. 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
Insufficient current to melt the wire off cleanly
When the filler wire is in direct contract with the base metal
V groove or U groove

28. In the GMAW process what does amperage control?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
To prevent leakage - Carbon Dioxide (CO2)
Penetration and burn - off rate of the electrode
SMAW - GTAW

29. What does a flowmeter do and what does it measure?
Flux cored wires
Controls the rate of flow of a shielding gas to the gun nozzle
(DCEP) Direct Current Electrode Positive or Reverse polarity
Generally not as accurate

30. How are GMAW guns rated?
...
By there current carrying capacity
These terms are quite restrictive and often technically incorrect
Voltage is the force that overcomes resistance to allow amperage flow

31. What effect does increasing and decreasing the inductance have on the weld?
Short- circuiting transfer - Globular transfer - Spray 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
Shielding the molten weld metal from atmospheric contamination
To prevent leakage - Carbon Dioxide (CO2)

32. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
...
5.8 to 12.5 L/min
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Pressure - The rate of flow of a shielding gas

33. Give a description of 'pinch effect'
Welding process that joins metals by heating them with an electric arc
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Controls the rate of flow of a shielding gas to the gun nozzle

34. 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
Gives arc voltage values to the control system of the feeder
The negative side of a welding unit
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

35. With straight polarity where is 2/3 of the arc energy?
The negative side of a welding unit
V groove or U groove
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
(DCEP) Direct Current Electrode Positive or Reverse polarity

36. What processes are constant current (CC) power sources designed to be used with?
SMAW - GTAW
Cause flaking - which can clog the liner and contact tube
The time rate of response for the current rise and fall
20 to 200 times per second

37. Why is a fiber washer required and what cylinder gas requires it?
To prevent leakage - Carbon Dioxide (CO2)
SMAW - GTAW
Speed of the feed motor and - starting / stopping electrode feed
Higher 26 to 35 arc volts

38. Draw a typical volt amp curve for a machine that is designed for GMAW
Pressure - The rate of flow of a shielding gas
Wire feed speed - Voltage control
Higher 26 to 35 arc volts
If you dont know this check your phone

39. What controls the wire speed on a voltage sensing wire feeder?
Spatter problems and poor weld appearance
National Electrical Manufactures Association
The Arc voltage
1/4 inch to 1/2 inch

40. What is an advantage of pulsed arc transfer with GMAW?
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
Reducing the gas source pressure to a constant working pressure
Gives arc voltage values to the control system of the feeder

41. What does the wire feeder control?
Penetration and burn - off rate of the electrode
Flux cored wires
To prevent drawing of liquid CO2 (Carbon Dioxide)
Speed of the feed motor and - starting / stopping electrode feed

42. What does the abbreviation NEMA stand for?
When the filler wire is in direct contract with the base metal
SMAW - GTAW
To prevent leakage - Carbon Dioxide (CO2)
National Electrical Manufactures Association

43. List several industries that would use GMAW
Wire feed speed
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
Pressure vessels and the piping industry

44. What is the purpose of the shielding gas used in GMAW?
Penetration and burn - off rate of the electrode
Shielding the molten weld metal from atmospheric contamination
Spatter problems and poor weld appearance
SMAW - GTAW

45. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Penetration and burn - off rate of the electrode
Higher 26 to 35 arc volts
20 to 200 times per second
These terms are quite restrictive and often technically incorrect

46. 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
Constant- speed wire feeders and Voltage- sennsing wire feeders
Insufficient current to melt the wire off cleanly
(DCEP) Direct Current Electrode Positive or Reverse polarity

47. What are the 2 types of wire feeders available?
When the filler wire is in direct contract with the base metal
Puddle fluidity
Constant- speed wire feeders and Voltage- sennsing wire feeders
The resistace to electrical current flow increases with it. Causing the electrode to heat

48. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Motor driven generators - Transformer rectifiers - and Inverter designs
Duty cycle
Generally not as accurate
20 to 200 times per second

49. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
To prevent drawing of liquid CO2 (Carbon Dioxide)
3
To prevent leakage - Carbon Dioxide (CO2)
By there current carrying capacity

50. What output on the welding machine is used to rate the duty cycle?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Minutes of elapsed time continually run (out of 10 minutes)
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
When the filler wire is in direct contract with the base metal