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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 main purpose of 'slope'?
To limit the short circuiting current so that spatter is reduced
Minimum distortion due to low heat input
Cause flaking - which can clog the liner and contact tube
The resistace to electrical current flow increases with it. Causing the electrode to heat

2. What does voltage do in an electrical circuit?
Voltage is the force that overcomes resistance to allow amperage flow
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Wire feed speed - Voltage control
Aluminum wire

3. Why is the term GMAW preferred over MIG or MAG?
The negative side of a welding unit
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
These terms are quite restrictive and often technically incorrect
Gas metal arc welding

4. What does inductance control?
Pressure vessels and the piping industry
Aluminum wire
The time rate of response for the current rise and fall
Gas metal arc welding

5. 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
To limit the short circuiting current so that spatter is reduced
Constant voltage (CV)
AWS and CSA

6. What current and polarity is generally used with GMAW?
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Insufficient current to melt the wire off cleanly
3
DCEP (Direct Current Electrode Positive) Reverse Polarity

7. What does the term GMAW identify?
Generally not as accurate
Speed of the feed motor and - starting / stopping electrode feed
The negative side of a welding unit
Gas metal arc welding

8. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
85%
AWS and CSA
By there current carrying capacity
Penetration and burn - off rate of the electrode

9. Draw a typical volt amp curve for a machine that is designed for GMAW
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Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Constant voltage (CV)
V groove or U groove

10. What happens when the electrode extension is increased?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
The resistace to electrical current flow increases with it. Causing the electrode to heat
Higher 26 to 35 arc volts
Speed of the feed motor and - starting / stopping electrode feed

11. A pull type drive system is usually used on what type of material?
Wire feed speed - Voltage control
15 feet (4.5 meters)
Aluminum wire
By there current carrying capacity

12. What wire are knurled drive rolls most commonly used on?
Flux cored wires
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3
85%

13. What processes are constant current (CC) power sources designed to be used with?
SMAW - GTAW
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Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
When the filler wire is in direct contract with the base metal

14. What does a flowmeter do and what does it measure?
...
Controls the rate of flow of a shielding gas to the gun nozzle
Insufficient current to melt the wire off cleanly
Speed of the feed motor and - starting / stopping electrode feed

15. What does the abbreviation NEMA stand for?
The negative side of a welding unit
By there current carrying capacity
Controls the rate of flow of a shielding gas to the gun nozzle
National Electrical Manufactures Association

16. How are GMAW guns rated?
To limit the short circuiting current so that spatter is reduced
Aluminum wire
20 to 200 times per second
By there current carrying capacity

17. Why is globular transfer generally avoided with GMAW?
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Spatter problems and poor weld appearance
Gas metal arc welding
By there current carrying capacity

18. List the three methods of metal transfer with GMAW
Insufficient current to melt the wire off cleanly
Controls the rate of flow of a shielding gas to the gun nozzle
Short- circuiting transfer - Globular transfer - Spray transfer
...

19. List the basic equipment requirements for the GMAW process
The time rate of response for the current rise and fall
The Arc voltage
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
(DCEP) Direct Current Electrode Positive or Reverse polarity

20. What controls the wire speed on a voltage sensing wire feeder?
The Arc voltage
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

21. List several industries that would use GMAW
Constant- speed wire feeders and Voltage- sennsing wire feeders
5.8 to 12.5 L/min
Pressure vessels and the piping industry
Puddle fluidity

22. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Puddle fluidity
20 to 200 times per second
Gives arc voltage values to the control system of the feeder
Pressure - The rate of flow of a shielding gas

23. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
Flux cored wires
...
Pressure vessels and the piping industry
SMAW - GTAW

24. What output on the welding machine is used to rate the duty cycle?
Puddle fluidity
Minutes of elapsed time continually run (out of 10 minutes)
National Electrical Manufactures Association
Cause flaking - which can clog the liner and contact tube

25. What is the purpose of the shielding gas used in GMAW?
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
Shielding the molten weld metal from atmospheric contamination
Generally not as accurate

26. 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
Shielding the molten weld metal from atmospheric contamination
Speed of the feed motor and - starting / stopping electrode feed
Minutes of elapsed time continually run (out of 10 minutes)

27. With straight polarity where is 2/3 of the arc energy?
The negative side of a welding unit
Gas metal arc welding
Voltage is the force that overcomes resistance to allow amperage flow
Shielding the molten weld metal from atmospheric contamination

28. In the GMAW process what does amperage control?
Flux cored wires
Penetration and burn - off rate of the electrode
Speed of the feed motor and - starting / stopping electrode feed
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

29. What type of power source is used with a constant speed wire feeder?
Constant voltage (CV)
By there current carrying capacity
Constant current (CC)
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30. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Duty cycle
The time rate of response for the current rise and fall
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Pressure vessels and the piping industry

31. Why is a fiber washer required and what cylinder gas requires it?
Welding process that joins metals by heating them with an electric arc
National Electrical Manufactures Association
To prevent leakage - Carbon Dioxide (CO2)
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

32. Why must CO2 cylinders be used in the vertical position?
5.8 to 12.5 L/min
Wire feed speed
To prevent drawing of liquid CO2 (Carbon Dioxide)
Constant- speed wire feeders and Voltage- sennsing wire feeders

33. What 2 controls are found on a GMAW set- up?
V groove or U groove
Flux cored wires
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

34. How many times per second does short circuiting take place?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
20 to 200 times per second
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
85%

35. What is the maximum distance that hard wire can be successfully pushed?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
12 to 22 arc volts
Aluminum wire
15 feet (4.5 meters)

36. What is the recommended electrode stick- out for .035 solid wire?
...
To limit the short circuiting current so that spatter is reduced
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

37. What power sources are used with the GMAW Process?
V groove or U groove
By there current carrying capacity
Motor driven generators - Transformer rectifiers - and Inverter designs
The time rate of response for the current rise and fall

38. What is another term for electrode holders for GMAW?
Guns
Wire feed speed
85%
Voltage is the force that overcomes resistance to allow amperage flow

39. What is an advantage of pulsed arc transfer with GMAW?
Welding Current - Filler wire diameter - arc length - type of shielding - position of 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
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Wire feeds smoothly (yet will slip should a problem occur in the gun)

40. Regulators control_____________ flowmeters SHOW____________.
Pressure - The rate of flow of a shielding gas
Wire feeds smoothly (yet will slip should a problem occur in the gun)
When the filler wire is in direct contract with the base metal
The negative side of a welding unit

41. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
1/4 inch to 1/2 inch
Flux cored wires
3
These terms are quite restrictive and often technically incorrect

42. What is the preferred drive roll design for solid wires?
Gives arc voltage values to the control system of the feeder
(DCEP) Direct Current Electrode Positive or Reverse polarity
When the filler wire is in direct contract with the base metal
V groove or U groove

43. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
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
Generally not as accurate
Cause flaking - which can clog the liner and contact tube
Voltage is the force that overcomes resistance to allow amperage flow

44. What is the required arc voltage used for short circuit transfer?
Puddle fluidity
Higher 26 to 35 arc volts
Penetration and burn - off rate of the electrode
12 to 22 arc volts

45. What does the wire feeder control?
Minutes of elapsed time continually run (out of 10 minutes)
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Speed of the feed motor and - starting / stopping electrode feed

46. What is the effect of too much slope?
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
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Insufficient current to melt the wire off cleanly

47. What is a typical flow rate of CO2 for short circuit transfer?
Gives arc voltage values to the control system of the feeder
Wire feed speed
5.8 to 12.5 L/min
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

48. Give a description of 'pinch effect'
These terms are quite restrictive and often technically incorrect
Penetration and burn - off rate of the electrode
Wire feed speed - Voltage control
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

49. What 2 organizations designate specifications for GMAW wires?
Duty cycle
AWS and CSA
3
12 to 22 arc volts

50. In the GMAW process what does voltage control?
Voltage is the force that overcomes resistance to allow amperage flow
Aluminum wire
Puddle fluidity
AWS and CSA