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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.
Don't refresh. All questions and answers are randomly picked and ordered every time you load a test.

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. How are GMAW guns rated?
Guns
By there current carrying capacity
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Spatter problems and poor weld appearance

2. What is the effect of too much slope?
Insufficient current to melt the wire off cleanly
1/4 inch to 1/2 inch
(DCEP) Direct Current Electrode Positive or Reverse polarity
V groove or U groove

3. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Generally not as accurate
Minutes of elapsed time continually run (out of 10 minutes)
Duty cycle
The time rate of response for the current rise and fall

4. What is the maximum distance that hard wire can be successfully pushed?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Wire feed speed
15 feet (4.5 meters)
Gas metal arc welding

5. List 3 forms compressed gases may be supplied for welding
To prevent drawing of liquid CO2 (Carbon Dioxide)
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
By there current carrying capacity
Aluminum wire

6. With straight polarity where is 2/3 of the arc energy?
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
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
DCEP (Direct Current Electrode Positive) Reverse Polarity
The negative side of a welding unit

7. When is the metal transferred with short circuit transfer?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Welding process that joins metals by heating them with an electric arc
DCEP (Direct Current Electrode Positive) Reverse Polarity
When the filler wire is in direct contract with the base metal

8. What does the abbreviation NEMA stand for?
20 to 200 times per second
By there current carrying capacity
National Electrical Manufactures Association
Penetration and burn - off rate of the electrode

9. What does inductance control?
5.8 to 12.5 L/min
The time rate of response for the current rise and fall
...
The negative side of a welding unit

10. What controls the wire speed on a voltage sensing wire feeder?
AWS and CSA
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
The Arc voltage
Constant- speed wire feeders and Voltage- sennsing wire feeders

11. What 2 controls are found on a GMAW set- up?
Insufficient current to melt the wire off cleanly
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
Flux cored wires
Wire feed speed - Voltage control

12. 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
Minutes of elapsed time continually run (out of 10 minutes)
Duty cycle
...

13. What processes are constant current (CC) power sources designed to be used with?
SMAW - GTAW
Pressure vessels and the piping industry
The time rate of response for the current rise and fall
Gas metal arc welding

14. What is an advantage of pulsed arc transfer with GMAW?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Dry ice can form within the flow control openings and cause blockage of shielding gas
85%
Constant voltage (CV)

15. What 2 organizations designate specifications for GMAW wires?
National Electrical Manufactures Association
AWS and CSA
The time rate of response for the current rise and fall
15 feet (4.5 meters)

16. What is the recommended electrode stick- out for .035 solid wire?
1/4 inch to 1/2 inch
Minutes of elapsed time continually run (out of 10 minutes)
National Electrical Manufactures Association
Flux cored wires

17. How many times per second does short circuiting take place?
Voltage is the force that overcomes resistance to allow amperage flow
Pressure - The rate of flow of a shielding gas
20 to 200 times per second
Wire feeds smoothly (yet will slip should a problem occur in the gun)

18. What is the purpose of the shielding gas used in GMAW?
National Electrical Manufactures Association
Shielding the molten weld metal from atmospheric contamination
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Higher 26 to 35 arc volts

19. 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
The time rate of response for the current rise and fall
Pressure vessels and the piping industry
1/4 inch to 1/2 inch

20. What type of power source is used with a constant speed wire feeder?
1/4 inch to 1/2 inch
National Electrical Manufactures Association
These terms are quite restrictive and often technically incorrect
Constant voltage (CV)

21. What is the purpose of a regulator and what does it indicate on its gauges?
Aluminum wire
Reducing the gas source pressure to a constant working pressure
85%
Speed of the feed motor and - starting / stopping electrode feed

22. What wire are knurled drive rolls most commonly used on?
Gives arc voltage values to the control system of the feeder
85%
Welding process that joins metals by heating them with an electric arc
Flux cored wires

23. What is the main purpose of 'slope'?
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
To limit the short circuiting current so that spatter is reduced
Dry ice can form within the flow control openings and cause blockage of shielding gas
Wire feed speed - Voltage control

24. Draw a typical volt amp curve for a machine that is designed for GMAW
Wire feeds smoothly (yet will slip should a problem occur in the gun)
If you dont know this check your phone
SMAW - GTAW
Aluminum wire

25. What is the preferred drive roll design for solid wires?
Duty cycle
Wire feed speed
V groove or U groove
5.8 to 12.5 L/min

26. What does the term GMAW identify?
Constant current (CC)
Gas metal arc welding
Insufficient current to melt the wire off cleanly
DCEP (Direct Current Electrode Positive) Reverse Polarity

27. Why must CO2 cylinders be used in the vertical position?
...
Pressure - The rate of flow of a shielding gas
V groove or U groove
To prevent drawing of liquid CO2 (Carbon Dioxide)

28. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Welding process that joins metals by heating them with an electric arc
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Gives arc voltage values to the control system of the feeder
Guns

29. In the GMAW process what does amperage control?
Controls the rate of flow of a shielding gas to the gun nozzle
Penetration and burn - off rate of the electrode
Cause flaking - which can clog the liner and contact tube
National Electrical Manufactures Association

30. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
...
Speed of the feed motor and - starting / stopping electrode feed
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Generally not as accurate

31. What is the required arc voltage used for short circuit transfer?
Aluminum wire
12 to 22 arc volts
Wire feeds smoothly (yet will slip should a problem occur in the gun)
15 feet (4.5 meters)

32. Regulators control_____________ flowmeters SHOW____________.
Pressure - The rate of flow of a shielding gas
Minimum distortion due to low heat input
85%
Generally not as accurate

33. What would be an indication that the drive roll pressure is adjusted correctly?
Duty cycle
3
These terms are quite restrictive and often technically incorrect
Wire feeds smoothly (yet will slip should a problem occur in the gun)

34. What are the 2 types of wire feeders available?
V groove or U groove
Constant- speed wire feeders and Voltage- sennsing wire feeders
Pressure - The rate of flow of a shielding gas
The negative side of a welding unit

35. List 3 wire drive systems and give a short description of each
The negative side of a welding unit
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
85%

36. What is another term for electrode holders for GMAW?
85%
The Arc voltage
1/4 inch to 1/2 inch
Guns

37. Why is the term GMAW preferred over MIG or MAG?
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
These terms are quite restrictive and often technically incorrect
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Generally not as accurate

38. Why is a line heater required when using GMAW?
Dry ice can form within the flow control openings and cause blockage of shielding gas
Aluminum wire
Minutes of elapsed time continually run (out of 10 minutes)
Speed of the feed motor and - starting / stopping electrode feed

39. What effect does increasing and decreasing the inductance have on the weld?
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
20 to 200 times per second
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

40. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
If you dont know this check your phone
Voltage is the force that overcomes resistance to allow amperage flow
Higher 26 to 35 arc volts

41. What power sources are used with the GMAW Process?
To limit the short circuiting current so that spatter is reduced
Wire feed speed - Voltage control
Motor driven generators - Transformer rectifiers - and Inverter designs
Puddle fluidity

42. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Constant current (CC)
Generally not as accurate
Motor driven generators - Transformer rectifiers - and Inverter designs
By there current carrying capacity

43. A pull type drive system is usually used on what type of material?
Penetration and burn - off rate of the electrode
The Arc voltage
Aluminum wire
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

44. Why is a fiber washer required and what cylinder gas requires it?
20 to 200 times per second
To prevent leakage - Carbon Dioxide (CO2)
To limit the short circuiting current so that spatter is reduced
AWS and CSA

45. List several industries that would use GMAW
Pressure vessels and the piping industry
Voltage is the force that overcomes resistance to allow amperage flow
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
1/4 inch to 1/2 inch

46. Give a description of 'pinch effect'
20 to 200 times per second
Puddle fluidity
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

47. In the GMAW process what does voltage control?
Puddle fluidity
Generally not as accurate
Minimum distortion due to low heat input
The Arc voltage

48. Why is globular transfer generally avoided with GMAW?
The time rate of response for the current rise and fall
Spatter problems and poor weld appearance
Speed of the feed motor and - starting / stopping electrode feed
When the filler wire is in direct contract with the base metal

49. List the basic equipment requirements for the GMAW process
5.8 to 12.5 L/min
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

50. What does voltage do in an electrical circuit?
85%
20 to 200 times per second
Voltage is the force that overcomes resistance to allow amperage flow
The negative side of a welding unit