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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 pull type drive system is usually used on what type of material?
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DCEP (Direct Current Electrode Positive) Reverse Polarity
85%
Aluminum wire

2. What type of power source is commonly used with a voltage sensing wire feeder?
Duty cycle
These terms are quite restrictive and often technically incorrect
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

3. What happens when the electrode extension is increased?
The resistace to electrical current flow increases with it. Causing the electrode to heat
Duty cycle
Minimum distortion due to low heat input
Pressure - The rate of flow of a shielding gas

4. In the GMAW process what does voltage control?
Welding process that joins metals by heating them with an electric arc
Puddle fluidity
V groove or U groove
Aluminum wire

5. List several industries that would use GMAW
Pressure vessels and the piping industry
(DCEP) Direct Current Electrode Positive or Reverse polarity
Wire feed speed - Voltage control
Motor driven generators - Transformer rectifiers - and Inverter designs

6. What wire are knurled drive rolls most commonly used on?
Flux cored wires
The resistace to electrical current flow increases with it. Causing the electrode to heat
Short- circuiting transfer - Globular transfer - Spray transfer
Gas metal arc welding

7. What does the wire feeder control?
Pressure vessels and the piping industry
Cause flaking - which can clog the liner and contact tube
Speed of the feed motor and - starting / stopping electrode feed
Shielding the molten weld metal from atmospheric contamination

8. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Gives arc voltage values to the control system of the feeder
Controls the rate of flow of a shielding gas to the gun nozzle
DCEP (Direct Current Electrode Positive) Reverse Polarity
Aluminum wire

9. What does the abbreviation NEMA stand for?
National Electrical Manufactures Association
12 to 22 arc volts
Welding process that joins metals by heating them with an electric arc
Shielding the molten weld metal from atmospheric contamination

10. What is a solenoid valve and what actuates it?
SMAW - GTAW
To prevent drawing of liquid CO2 (Carbon Dioxide)
Constant current (CC)
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

11. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
Minimum distortion due to low heat input
Flux cored wires
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
(DCEP) Direct Current Electrode Positive or Reverse polarity

12. List 3 wire drive systems and give a short description of each
Shielding the molten weld metal from atmospheric contamination
Wire feed speed - Voltage control
Wire feeds smoothly (yet will slip should a problem occur in the gun)
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

13. 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)
National Electrical Manufactures Association
Dry ice can form within the flow control openings and cause blockage of shielding gas
Insufficient current to melt the wire off cleanly

14. What type of power source is used with a constant speed wire feeder?
15 feet (4.5 meters)
Welding process that joins metals by heating them with an electric arc
Shielding the molten weld metal from atmospheric contamination
Constant voltage (CV)

15. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Duty cycle
Speed of the feed motor and - starting / stopping electrode feed
DCEP (Direct Current Electrode Positive) Reverse Polarity
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

16. What is the required arc voltage used for short circuit transfer?
Puddle fluidity
The Arc voltage
12 to 22 arc volts
Flux cored wires

17. Give a brief description of the GMAW process
Welding process that joins metals by heating them with an electric arc
Shielding the molten weld metal from atmospheric contamination
The time rate of response for the current rise and fall
Constant voltage (CV)

18. What current and polarity is generally used with GMAW?
Spatter problems and poor weld appearance
1/4 inch to 1/2 inch
DCEP (Direct Current Electrode Positive) Reverse Polarity
Controls the rate of flow of a shielding gas to the gun nozzle

19. How many times per second does short circuiting take place?
Welding process that joins metals by heating them with an electric arc
Minimum distortion due to low heat input
20 to 200 times per second
Minutes of elapsed time continually run (out of 10 minutes)

20. What processes are constant current (CC) power sources designed to be used with?
Aluminum wire
1/4 inch to 1/2 inch
Higher 26 to 35 arc volts
SMAW - GTAW

21. List the factors that determine the mode of metal transfer
Spatter problems and poor weld appearance
Controls the rate of flow of a shielding gas to the gun nozzle
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Constant voltage (CV)

22. What are the 2 types of wire feeders available?
By there current carrying capacity
Gives arc voltage values to the control system of the feeder
The time rate of response for the current rise and fall
Constant- speed wire feeders and Voltage- sennsing wire feeders

23. What is the recommended electrode stick- out for .035 solid wire?
Welding process that joins metals by heating them with an electric arc
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Gas metal arc welding
1/4 inch to 1/2 inch

24. Regulators control_____________ flowmeters SHOW____________.
When the filler wire is in direct contract with the base metal
Aluminum wire
Constant voltage (CV)
Pressure - The rate of flow of a shielding gas

25. What is the purpose of the shielding gas used in GMAW?
Higher 26 to 35 arc volts
Shielding the molten weld metal from atmospheric contamination
Flux cored wires
Pressure vessels and the piping industry

26. List the three methods of metal transfer with GMAW
Short- circuiting transfer - Globular transfer - Spray transfer
Cause flaking - which can clog the liner and contact tube
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Motor driven generators - Transformer rectifiers - and Inverter designs

27. List 3 forms compressed gases may be supplied for welding
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
Constant- speed wire feeders and Voltage- sennsing wire feeders
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

28. What controls the wire speed on a voltage sensing wire feeder?
Gives arc voltage values to the control system of the feeder
Pressure - The rate of flow of a shielding gas
The Arc voltage
SMAW - GTAW

29. 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
The time rate of response for the current rise and fall
Cause flaking - which can clog the liner and contact tube

30. What is an advantage of pulsed arc transfer with GMAW?
AWS and CSA
The time rate of response for the current rise and fall
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
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31. Give a description of 'pinch effect'
Reducing the gas source pressure to a constant working pressure
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Voltage is the force that overcomes resistance to allow amperage flow
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

32. How are GMAW guns rated?
Dry ice can form within the flow control openings and cause blockage of shielding gas
AWS and CSA
By there current carrying capacity
Pressure vessels and the piping industry

33. What controls amperage when using GMAW?
5.8 to 12.5 L/min
The resistace to electrical current flow increases with it. Causing the electrode to heat
Constant voltage (CV)
Wire feed speed

34. What is the maximum distance that hard wire can be successfully pushed?
15 feet (4.5 meters)
The resistace to electrical current flow increases with it. Causing the electrode to heat
(DCEP) Direct Current Electrode Positive or Reverse polarity
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

35. List the basic equipment requirements for the GMAW process
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Minutes of elapsed time continually run (out of 10 minutes)
Motor driven generators - Transformer rectifiers - and Inverter designs
Higher 26 to 35 arc volts

36. What power sources are used with the GMAW Process?
20 to 200 times per second
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
12 to 22 arc volts
Motor driven generators - Transformer rectifiers - and Inverter designs

37. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
...
Higher 26 to 35 arc volts
SMAW - GTAW

38. Why must CO2 cylinders be used in the vertical position?
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 feed speed - Voltage control
The negative side of a welding unit
To prevent drawing of liquid CO2 (Carbon Dioxide)

39. What is the effect of too much slope?
Shielding the molten weld metal from atmospheric contamination
Insufficient current to melt the wire off cleanly
Puddle fluidity
Welding process that joins metals by heating them with an electric arc

40. In the GMAW process what does amperage control?
Cause flaking - which can clog the liner and contact tube
Penetration and burn - off rate of the electrode
Flux cored wires
Voltage is the force that overcomes resistance to allow amperage flow

41. What is the purpose of a regulator and what does it indicate on its gauges?
Reducing the gas source pressure to a constant working pressure
Controls the rate of flow of a shielding gas to the gun nozzle
12 to 22 arc volts
Higher 26 to 35 arc volts

42. 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
To prevent drawing of liquid CO2 (Carbon Dioxide)
Constant current (CC)
85%

43. What is the preferred drive roll design for solid wires?
Wire feed speed
Flux cored wires
Constant- speed wire feeders and Voltage- sennsing wire feeders
V groove or U groove

44. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Higher 26 to 35 arc volts
Speed of the feed motor and - starting / stopping electrode feed
Penetration and burn - off rate of the electrode
The resistace to electrical current flow increases with it. Causing the electrode to heat

45. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
Reducing the gas source pressure to a constant working pressure
3
15 feet (4.5 meters)
Minutes of elapsed time continually run (out of 10 minutes)

46. What 2 controls are found on a GMAW set- up?
Spatter problems and poor weld appearance
The negative side of a welding unit
Wire feed speed - Voltage control
Flux cored wires

47. What is the main purpose of 'slope'?
To limit the short circuiting current so that spatter is reduced
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
3
The time rate of response for the current rise and fall

48. What is a typical flow rate of CO2 for short circuit transfer?
Controls the rate of flow of a shielding gas to the gun nozzle
Wire feed speed - Voltage control
By there current carrying capacity
5.8 to 12.5 L/min

49. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
To prevent drawing of liquid CO2 (Carbon Dioxide)
Generally not as accurate
The negative side of a welding unit
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50. What is the disadvantage of the gauge preset type of regulator/flowmeter?
85%
Generally not as accurate
Spatter problems and poor weld appearance
Speed of the feed motor and - starting / stopping electrode feed