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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.
3
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Higher 26 to 35 arc volts
To prevent leakage - Carbon Dioxide (CO2)

2. What is the recommended electrode stick- out for .035 solid wire?
Insufficient current to melt the wire off cleanly
1/4 inch to 1/2 inch
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
Duty cycle

3. What is the main purpose of 'slope'?
To prevent drawing of liquid CO2 (Carbon Dioxide)
Duty cycle
To limit the short circuiting current so that spatter is reduced
Wire feeds smoothly (yet will slip should a problem occur in the gun)

4. List the basic equipment requirements for the GMAW process
To limit the short circuiting current so that spatter is reduced
20 to 200 times per second
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

5. What controls amperage when using GMAW?
Wire feed speed
Gives arc voltage values to the control system of the feeder
15 feet (4.5 meters)
Motor driven generators - Transformer rectifiers - and Inverter designs

6. What does the term GMAW identify?
15 feet (4.5 meters)
Gas metal arc welding
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Higher 26 to 35 arc volts

7. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
(DCEP) Direct Current Electrode Positive or Reverse polarity
Insufficient current to melt the wire off cleanly
Higher 26 to 35 arc volts
Wire feeds smoothly (yet will slip should a problem occur in the gun)

8. What type of power source is used with a constant speed wire feeder?
Constant voltage (CV)
To prevent drawing of liquid CO2 (Carbon Dioxide)
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Reducing the gas source pressure to a constant working pressure

9. What is a typical flow rate of CO2 for short circuit transfer?
5.8 to 12.5 L/min
These terms are quite restrictive and often technically incorrect
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Speed of the feed motor and - starting / stopping electrode feed

10. What is another term for electrode holders for GMAW?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Guns
Minutes of elapsed time continually run (out of 10 minutes)
If you dont know this check your phone

11. What is the required arc voltage used for short circuit transfer?
By there current carrying capacity
12 to 22 arc volts
5.8 to 12.5 L/min
Cause flaking - which can clog the liner and contact tube

12. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Generally not as accurate
Wire feeds smoothly (yet will slip should a problem occur in the gun)
These terms are quite restrictive and often technically incorrect
Spatter problems and poor weld appearance

13. What is the purpose of the shielding gas used in GMAW?
Shielding the molten weld metal from atmospheric contamination
To limit the short circuiting current so that spatter is reduced
To prevent leakage - Carbon Dioxide (CO2)
Gas metal arc welding

14. In the GMAW process what does amperage control?
Penetration and burn - off rate of the electrode
Duty cycle
Guns
Generally not as accurate

15. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
(DCEP) Direct Current Electrode Positive or Reverse polarity
AWS and CSA
85%
Voltage is the force that overcomes resistance to allow amperage flow

16. List several industries that would use GMAW
Pressure vessels and the piping industry
If you dont know this check your phone
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
12 to 22 arc volts

17. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Spatter problems and poor weld appearance
DCEP (Direct Current Electrode Positive) Reverse Polarity
Cause flaking - which can clog the liner and contact tube
Duty cycle

18. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
Constant- speed wire feeders and Voltage- sennsing wire feeders
DCEP (Direct Current Electrode Positive) Reverse Polarity
...
Wire feeds smoothly (yet will slip should a problem occur in the gun)

19. What are the 2 types of wire feeders available?
Constant current (CC)
Constant- speed wire feeders and Voltage- sennsing wire feeders
Pressure - The rate of flow of a shielding gas
Penetration and burn - off rate of the electrode

20. What is a solenoid valve and what actuates it?
To limit the short circuiting current so that spatter is reduced
When the filler wire is in direct contract with the base metal
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on 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

21. List 3 wire drive systems and give a short description of each
(DCEP) Direct Current Electrode Positive or Reverse polarity
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
Motor driven generators - Transformer rectifiers - and Inverter designs

22. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
V groove or U groove
Higher 26 to 35 arc volts
If you dont know this check your phone
Dry ice can form within the flow control openings and cause blockage of shielding gas

23. What wire are knurled drive rolls most commonly used on?
Gas metal arc welding
Constant voltage (CV)
Flux cored wires
1/4 inch to 1/2 inch

24. What is the key advantage of short circuiting transfer?
The resistace to electrical current flow increases with it. Causing the electrode to heat
Gives arc voltage values to the control system of the feeder
Minimum distortion due to low heat input
Aluminum wire

25. What is the preferred drive roll design for solid wires?
Controls the rate of flow of a shielding gas to the gun nozzle
V groove or U groove
SMAW - GTAW
The negative side of a welding unit

26. What is the purpose of a regulator and what does it indicate on its gauges?
If you dont know this check your phone
SMAW - GTAW
Reducing the gas source pressure to a constant working pressure
Pressure vessels and the piping industry

27. How many times per second does short circuiting take place?
20 to 200 times per second
Pressure vessels and the piping industry
Constant current (CC)
The time rate of response for the current rise and fall

28. What effect does increasing and decreasing the inductance have on the weld?
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
The Arc voltage
When the filler wire is in direct contract with the base metal
Controls the rate of flow of a shielding gas to the gun nozzle

29. What is the effect of too much slope?
1/4 inch to 1/2 inch
Gas metal arc welding
Minimum distortion due to low heat input
Insufficient current to melt the wire off cleanly

30. 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
Cause flaking - which can clog the liner and contact tube
Shielding the molten weld metal from atmospheric contamination
These terms are quite restrictive and often technically incorrect

31. In the GMAW process what does voltage control?
Penetration and burn - off rate of the electrode
These terms are quite restrictive and often technically incorrect
Puddle fluidity
Minutes of elapsed time continually run (out of 10 minutes)

32. What happens when the electrode extension is increased?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
The resistace to electrical current flow increases with it. Causing the electrode to heat
Penetration and burn - off rate of the electrode
Aluminum wire

33. What current and polarity is generally used with GMAW?
Flux cored wires
Puddle fluidity
DCEP (Direct Current Electrode Positive) Reverse Polarity
Guns

34. How are GMAW guns rated?
Speed of the feed motor and - starting / stopping electrode feed
By there current carrying capacity
These terms are quite restrictive and often technically incorrect
Wire feed speed

35. What does the abbreviation NEMA stand for?
By there current carrying capacity
National Electrical Manufactures Association
1/4 inch to 1/2 inch
5.8 to 12.5 L/min

36. What 2 controls are found on a GMAW set- up?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Wire feed speed - Voltage control
Reducing the gas source pressure to a constant working pressure
Generally not as accurate

37. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Duty cycle
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
The negative side of a welding unit

38. Why is a line heater required when using GMAW?
Generally not as accurate
Dry ice can form within the flow control openings and cause blockage of shielding gas
Guns
When the filler wire is in direct contract with the base metal

39. What does inductance control?
To prevent drawing of liquid CO2 (Carbon Dioxide)
Pressure vessels and the piping industry
Flux cored wires
The time rate of response for the current rise and fall

40. What would be an indication that the drive roll pressure is adjusted correctly?
Wire feed speed - Voltage control
Short- circuiting transfer - Globular transfer - Spray transfer
SMAW - GTAW
Wire feeds smoothly (yet will slip should a problem occur in the gun)

41. What does the wire feeder control?
Constant current (CC)
Speed of the feed motor and - starting / stopping electrode feed
Motor driven generators - Transformer rectifiers - and Inverter designs
Minutes of elapsed time continually run (out of 10 minutes)

42. What is the maximum distance that hard wire can be successfully pushed?
Penetration and burn - off rate of the electrode
AWS and CSA
Controls the rate of flow of a shielding gas to the gun nozzle
15 feet (4.5 meters)

43. List the factors that determine the mode of metal transfer
Constant voltage (CV)
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Shielding the molten weld metal from atmospheric contamination
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

44. What processes are constant current (CC) power sources designed to be used with?
By there current carrying capacity
20 to 200 times per second
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
SMAW - GTAW

45. What 2 organizations designate specifications for GMAW wires?
Gas metal arc welding
SMAW - GTAW
AWS and CSA
Puddle fluidity

46. List 3 forms compressed gases may be supplied for welding
Constant voltage (CV)
By there current carrying capacity
Flux cored wires
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

47. Why is the term GMAW preferred over MIG or MAG?
...
Constant current (CC)
The Arc voltage
These terms are quite restrictive and often technically incorrect

48. Give a brief description of the GMAW process
1/4 inch to 1/2 inch
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
Wire feeds smoothly (yet will slip should a problem occur in the gun)

49. Why is globular transfer generally avoided with GMAW?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Spatter problems and poor weld appearance
Dry ice can form within the flow control openings and cause blockage of shielding gas
The negative side of a welding unit

50. List the three methods of metal transfer with GMAW
Voltage is the force that overcomes resistance to allow amperage flow
Short- circuiting transfer - Globular transfer - Spray transfer
Wire feed speed
Wire feeds smoothly (yet will slip should a problem occur in the gun)