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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. List several industries that would use GMAW
Pressure vessels and the piping industry
Higher 26 to 35 arc volts
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

2. How are GMAW guns rated?
National Electrical Manufactures Association
By there current carrying capacity
If you dont know this check your phone
Motor driven generators - Transformer rectifiers - and Inverter designs

3. What does voltage do in an electrical circuit?
Voltage is the force that overcomes resistance to allow amperage flow
By there current carrying capacity
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Puddle fluidity

4. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Duty cycle
15 feet (4.5 meters)
When the filler wire is in direct contract with the base metal
Wire feeds smoothly (yet will slip should a problem occur in the gun)

5. When is the metal transferred with short circuit transfer?
Gives arc voltage values to the control system of the feeder
Minimum distortion due to low heat input
When the filler wire is in direct contract with the base metal
...

6. How many times per second does short circuiting take place?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
15 feet (4.5 meters)
Cause flaking - which can clog the liner and contact tube
20 to 200 times per second

7. Why is a fiber washer required and what cylinder gas requires it?
The resistace to electrical current flow increases with it. Causing the electrode to heat
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 negative side of a welding unit
To prevent leakage - Carbon Dioxide (CO2)

8. What are the 2 types of wire feeders available?
Wire feed speed
Higher 26 to 35 arc volts
Constant- speed wire feeders and Voltage- sennsing wire feeders
Controls the rate of flow of a shielding gas to the gun nozzle

9. What is the key advantage of short circuiting transfer?
Spatter problems and poor weld appearance
Minimum distortion due to low heat input
National Electrical Manufactures Association
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

10. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Higher 26 to 35 arc volts
5.8 to 12.5 L/min
Guns
Gives arc voltage values to the control system of the feeder

11. What effect does increasing and decreasing the inductance have on the weld?
AWS and CSA
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Wire feed speed - Voltage control
(DCEP) Direct Current Electrode Positive or Reverse polarity

12. What does the abbreviation NEMA stand for?
...
15 feet (4.5 meters)
(DCEP) Direct Current Electrode Positive or Reverse polarity
National Electrical Manufactures Association

13. What does a flowmeter do and what does it measure?
The time rate of response for the current rise and fall
Pressure - The rate of flow of a shielding gas
Controls the rate of flow of a shielding gas to the gun nozzle
...

14. In the GMAW process what does amperage control?
If you dont know this check your phone
Penetration and burn - off rate of the electrode
1/4 inch to 1/2 inch
Minutes of elapsed time continually run (out of 10 minutes)

15. In the GMAW process what does voltage control?
Generally not as accurate
DCEP (Direct Current Electrode Positive) Reverse Polarity
Puddle fluidity
Wire feed speed

16. What is the main purpose of 'slope'?
Penetration and burn - off rate of the electrode
Wire feed speed - Voltage control
Constant- speed wire feeders and Voltage- sennsing wire feeders
To limit the short circuiting current so that spatter is reduced

17. What is a solenoid valve and what actuates it?
Welding process that joins metals by heating them with an electric arc
The negative side of a welding unit
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

18. 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
V groove or U groove
Dry ice can form within the flow control openings and cause blockage of shielding gas
Pressure vessels and the piping industry

19. What is an advantage of pulsed arc transfer with GMAW?
Higher 26 to 35 arc volts
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
DCEP (Direct Current Electrode Positive) Reverse Polarity

20. What does the wire feeder control?
Dry ice can form within the flow control openings and cause blockage of shielding gas
Guns
Pressure - The rate of flow of a shielding gas
Speed of the feed motor and - starting / stopping electrode feed

21. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
5.8 to 12.5 L/min
Cause flaking - which can clog the liner and contact tube
Duty cycle
The resistace to electrical current flow increases with it. Causing the electrode to heat

22. What processes are constant current (CC) power sources designed to be used with?
AWS and CSA
Shielding the molten weld metal from atmospheric contamination
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
SMAW - GTAW

23. Give a description of 'pinch effect'
Duty cycle
These terms are quite restrictive and often technically incorrect
Guns
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

24. What 2 controls are found on a GMAW set- up?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Wire feed speed - Voltage control
20 to 200 times per second
Constant current (CC)

25. What type of power source is commonly used with a voltage sensing wire feeder?
Constant current (CC)
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Aluminum wire
Penetration and burn - off rate of the electrode

26. What is the purpose of a regulator and what does it indicate on its gauges?
The negative side of a welding unit
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
If you dont know this check your phone
Reducing the gas source pressure to a constant working pressure

27. What does inductance control?
By there current carrying capacity
The resistace to electrical current flow increases with it. Causing the electrode to heat
Higher 26 to 35 arc volts
The time rate of response for the current rise and fall

28. What is the required arc voltage used for short circuit transfer?
Wire feed speed - Voltage control
Higher 26 to 35 arc volts
12 to 22 arc volts
If you dont know this check your phone

29. 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)
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
V groove or U groove
The negative side of a welding unit

30. What happens when the electrode extension is increased?
85%
...
The resistace to electrical current flow increases with it. Causing the electrode to heat
Speed of the feed motor and - starting / stopping electrode feed

31. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
National Electrical Manufactures Association
Higher 26 to 35 arc volts
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
20 to 200 times per second

32. Draw a typical volt amp curve for a machine that is designed for GMAW
3
If you dont know this check your phone
Guns
The negative side of a welding unit

33. What controls the wire speed on a voltage sensing wire feeder?
Constant voltage (CV)
Minutes of elapsed time continually run (out of 10 minutes)
The Arc voltage
By there current carrying capacity

34. 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
When the filler wire is in direct contract with the base metal
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 current (CC)

35. What output on the welding machine is used to rate the duty cycle?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Gas metal arc welding
12 to 22 arc volts
Minutes of elapsed time continually run (out of 10 minutes)

36. List the basic equipment requirements for the GMAW process
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Short- circuiting transfer - Globular transfer - Spray transfer
The time rate of response for the current rise and fall
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

37. List 3 forms compressed gases may be supplied for welding
Voltage is the force that overcomes resistance to allow amperage flow
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
If you dont know this check your phone
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

38. What type of power source is used with a constant speed wire feeder?
Minimum distortion due to low heat input
...
Guns
Constant voltage (CV)

39. What is a typical flow rate of CO2 for short circuit transfer?
Motor driven generators - Transformer rectifiers - and Inverter designs
5.8 to 12.5 L/min
Cause flaking - which can clog the liner and contact tube
DCEP (Direct Current Electrode Positive) Reverse Polarity

40. What power sources are used with the GMAW Process?
Pressure - The rate of flow of a shielding gas
Minimum distortion due to low heat input
Welding process that joins metals by heating them with an electric arc
Motor driven generators - Transformer rectifiers - and Inverter designs

41. What wire are knurled drive rolls most commonly used on?
Flux cored wires
Motor driven generators - Transformer rectifiers - and Inverter designs
Pressure - The rate of flow of a shielding gas
Puddle fluidity

42. Why is globular transfer generally avoided with GMAW?
Spatter problems and poor weld appearance
Speed of the feed motor and - starting / stopping electrode feed
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Motor driven generators - Transformer rectifiers - and Inverter designs

43. Why must CO2 cylinders be used in the vertical position?
5.8 to 12.5 L/min
Minutes of elapsed time continually run (out of 10 minutes)
To prevent drawing of liquid CO2 (Carbon Dioxide)
By there current carrying capacity

44. What 2 organizations designate specifications for GMAW wires?
Pressure vessels and the piping industry
12 to 22 arc volts
SMAW - GTAW
AWS and CSA

45. Regulators control_____________ flowmeters SHOW____________.
Insufficient current to melt the wire off cleanly
To prevent leakage - Carbon Dioxide (CO2)
Speed of the feed motor and - starting / stopping electrode feed
Pressure - The rate of flow of a shielding gas

46. Give a brief description of the GMAW process
Controls the rate of flow of a shielding gas to the gun nozzle
National Electrical Manufactures Association
Welding process that joins metals by heating them with an electric arc
85%

47. What is the effect of too much slope?
Insufficient current to melt the wire off cleanly
12 to 22 arc volts
5.8 to 12.5 L/min
SMAW - GTAW

48. 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
Controls the rate of flow of a shielding gas to the gun nozzle
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

49. What controls amperage when using GMAW?
Wire feed speed
Penetration and burn - off rate of the electrode
To prevent leakage - Carbon Dioxide (CO2)
Wire feed speed - Voltage control

50. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
Gives arc voltage values to the control system of the feeder
1/4 inch to 1/2 inch
85%
Pressure - The rate of flow of a shielding gas