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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. What is the recommended electrode stick- out for .035 solid wire?
Flux cored wires
SMAW - GTAW
Wire feed speed - Voltage control
1/4 inch to 1/2 inch

2. 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
Minutes of elapsed time continually run (out of 10 minutes)
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

3. How many times per second does short circuiting take place?
To limit the short circuiting current so that spatter is reduced
Spatter problems and poor weld appearance
Pressure - The rate of flow of a shielding gas
20 to 200 times per second

4. 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
Constant- speed wire feeders and Voltage- sennsing wire feeders
Minimum distortion due to low heat input
Generally not as accurate

5. What does the wire feeder control?
Constant voltage (CV)
3
Speed of the feed motor and - starting / stopping electrode feed
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

6. What is the required arc voltage used for short circuit transfer?
12 to 22 arc volts
Short- circuiting transfer - Globular transfer - Spray transfer
To limit the short circuiting current so that spatter is reduced
If you dont know this check your phone

7. 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
Gas metal arc welding
12 to 22 arc volts
Voltage is the force that overcomes resistance to allow amperage flow

8. What are the 2 types of wire feeders available?
Penetration and burn - off rate of the electrode
Constant- speed wire feeders and Voltage- sennsing wire feeders
Dry ice can form within the flow control openings and cause blockage of shielding gas
3

9. What is another term for electrode holders for GMAW?
20 to 200 times per second
Guns
Aluminum wire
...

10. 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
These terms are quite restrictive and often technically incorrect
3

11. What is the effect of too much slope?
Pressure vessels and the piping industry
3
85%
Insufficient current to melt the wire off cleanly

12. What current and polarity is generally used with GMAW?
Shielding the molten weld metal from atmospheric contamination
To limit the short circuiting current so that spatter is reduced
DCEP (Direct Current Electrode Positive) Reverse Polarity
Penetration and burn - off rate of the electrode

13. What is the main purpose of 'slope'?
Minutes of elapsed time continually run (out of 10 minutes)
5.8 to 12.5 L/min
To limit the short circuiting current so that spatter is reduced
The resistace to electrical current flow increases with it. Causing the electrode to heat

14. List the three methods of metal transfer with GMAW
Short- circuiting transfer - Globular transfer - Spray transfer
Guns
If you dont know this check your phone
DCEP (Direct Current Electrode Positive) Reverse Polarity

15. What would be an indication that the drive roll pressure is adjusted correctly?
Aluminum wire
The resistace to electrical current flow increases with it. Causing the electrode to heat
5.8 to 12.5 L/min
Wire feeds smoothly (yet will slip should a problem occur in the gun)

16. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Duty cycle
Gas metal arc welding
The negative side of a welding unit
Minimum distortion due to low heat input

17. 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
Pressure vessels and the piping industry
1/4 inch to 1/2 inch
Gives arc voltage values to the control system of the feeder

18. Give a description of 'pinch effect'
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) Reverse Polarity
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
By there current carrying capacity

19. What does the term GMAW identify?
Penetration and burn - off rate of the electrode
Gas metal arc welding
Gives arc voltage values to the control system of the feeder
The negative side of a welding unit

20. What type of power source is commonly used with a voltage sensing wire feeder?
Constant current (CC)
To limit the short circuiting current so that spatter is reduced
Speed of the feed motor and - starting / stopping electrode feed
The time rate of response for the current rise and fall

21. What does the abbreviation NEMA stand for?
3
If you dont know this check your phone
Higher 26 to 35 arc volts
National Electrical Manufactures Association

22. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Minutes of elapsed time continually run (out of 10 minutes)
Constant voltage (CV)
Higher 26 to 35 arc volts
Welding process that joins metals by heating them with an electric arc

23. With straight polarity where is 2/3 of the arc energy?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
The negative side of a welding unit
5.8 to 12.5 L/min
15 feet (4.5 meters)

24. What does inductance control?
The time rate of response for the current rise and fall
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
When the filler wire is in direct contract with the base metal
Constant voltage (CV)

25. In the GMAW process what does voltage control?
Aluminum wire
Puddle fluidity
The time rate of response for the current rise and fall
AWS and CSA

26. What controls amperage when using GMAW?
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
Wire feed speed
Generally not as accurate

27. What controls the wire speed on a voltage sensing wire feeder?
The Arc voltage
Motor driven generators - Transformer rectifiers - and Inverter designs
National Electrical Manufactures Association
85%

28. What output on the welding machine is used to rate the duty cycle?
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Minutes of elapsed time continually run (out of 10 minutes)
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Puddle fluidity

29. 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
The Arc voltage
The resistace to electrical current flow increases with it. Causing the electrode to heat
Short- circuiting transfer - Globular transfer - Spray transfer

30. What is the key advantage of short circuiting transfer?
12 to 22 arc volts
V groove or U groove
Minimum distortion due to low heat input
Constant- speed wire feeders and Voltage- sennsing wire feeders

31. Why must CO2 cylinders be used in the vertical position?
SMAW - GTAW
To prevent drawing of liquid CO2 (Carbon Dioxide)
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
The time rate of response for the current rise and fall

32. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
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
3
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
5.8 to 12.5 L/min

33. What wire are knurled drive rolls most commonly used on?
To limit the short circuiting current so that spatter is reduced
Flux cored wires
Controls the rate of flow of a shielding gas to the gun nozzle
AWS and CSA

34. What is an advantage of pulsed arc transfer with GMAW?
When the filler wire is in direct contract with the base metal
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Cause flaking - which can clog the liner and contact tube
Constant voltage (CV)

35. List several industries that would use GMAW
Gas metal arc welding
Controls the rate of flow of a shielding gas to the gun nozzle
Pressure vessels and the piping industry
Wire feeds smoothly (yet will slip should a problem occur in the gun)

36. Draw a typical volt amp curve for a machine that is designed for GMAW
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
If you dont know this check your phone
Duty cycle
Penetration and burn - off rate of the electrode

37. A pull type drive system is usually used on what type of material?
Aluminum wire
Generally not as accurate
To prevent drawing of liquid CO2 (Carbon Dioxide)
The resistace to electrical current flow increases with it. Causing the electrode to heat

38. List 3 wire drive systems and give a short description of each
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
National Electrical Manufactures Association
Constant current (CC)

39. What processes are constant current (CC) power sources designed to be used with?
Motor driven generators - Transformer rectifiers - and Inverter designs
SMAW - GTAW
Higher 26 to 35 arc volts
By there current carrying capacity

40. What 2 controls are found on a GMAW set- up?
Wire feed speed - Voltage control
SMAW - GTAW
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
To prevent leakage - Carbon Dioxide (CO2)

41. What 2 organizations designate specifications for GMAW wires?
The time rate of response for the current rise and fall
If you dont know this check your phone
AWS and CSA
Guns

42. What is the purpose of the shielding gas used in GMAW?
Shielding the molten weld metal from atmospheric contamination
These terms are quite restrictive and often technically incorrect
To prevent drawing of liquid CO2 (Carbon Dioxide)
Flux cored wires

43. What happens when the electrode extension is increased?
Gives arc voltage values to the control system of the feeder
The resistace to electrical current flow increases with it. Causing the electrode to heat
If you dont know this check your phone
3

44. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
V groove or U groove
5.8 to 12.5 L/min
3
If you dont know this check your phone

45. In the GMAW process what does amperage control?
Dry ice can form within the flow control openings and cause blockage of shielding gas
Insufficient current to melt the wire off cleanly
Penetration and burn - off rate of the electrode
5.8 to 12.5 L/min

46. List the basic equipment requirements for the GMAW process
Duty cycle
The Arc voltage
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
These terms are quite restrictive and often technically incorrect

47. Why is a line heater required when using GMAW?
Dry ice can form within the flow control openings and cause blockage of shielding gas
Gives arc voltage values to the control system of the feeder
DCEP (Direct Current Electrode Positive) Reverse Polarity
15 feet (4.5 meters)

48. When is the metal transferred with short circuit transfer?
Puddle fluidity
3
When the filler wire is in direct contract with the base metal
AWS and CSA

49. Regulators control_____________ flowmeters SHOW____________.
12 to 22 arc volts
Generally not as accurate
Pressure - The rate of flow of a shielding gas
The time rate of response for the current rise and fall

50. What does voltage do in an electrical circuit?
If you dont know this check your phone
Voltage is the force that overcomes resistance to allow amperage flow
1/4 inch to 1/2 inch
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground