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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. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Wire feed speed
Gas metal arc welding
Motor driven generators - Transformer rectifiers - and Inverter designs
Higher 26 to 35 arc volts

2. Why is globular transfer generally avoided with GMAW?
To limit the short circuiting current so that spatter is reduced
DCEP (Direct Current Electrode Positive) Reverse Polarity
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Spatter problems and poor weld appearance

3. What is the required arc voltage used for short circuit transfer?
12 to 22 arc volts
Constant voltage (CV)
Generally not as accurate
To limit the short circuiting current so that spatter is reduced

4. Why is the term GMAW preferred over MIG or MAG?
To limit the short circuiting current so that spatter is reduced
These terms are quite restrictive and often technically incorrect
Shielding the molten weld metal from atmospheric contamination
Short- circuiting transfer - Globular transfer - Spray transfer

5. 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
Minimum distortion due to low heat input
Constant current (CC)
DCEP (Direct Current Electrode Positive) Reverse Polarity

6. What is another term for electrode holders for GMAW?
Duty cycle
85%
Guns
AWS and CSA

7. What happens when the electrode extension is increased?
The negative side of a welding unit
Shielding the molten weld metal from atmospheric contamination
The resistace to electrical current flow increases with it. Causing the electrode to heat
AWS and CSA

8. What effect does increasing and decreasing the inductance have on the weld?
If you dont know this check your phone
DCEP (Direct Current Electrode Positive) Reverse Polarity
Constant current (CC)
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

9. 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
12 to 22 arc volts
DCEP (Direct Current Electrode Positive) Reverse Polarity

10. What 2 organizations designate specifications for GMAW wires?
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
Generally not as accurate
AWS and CSA

11. In the GMAW process what does voltage control?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Aluminum wire
Minutes of elapsed time continually run (out of 10 minutes)
Puddle fluidity

12. What is the effect of too much slope?
Pressure vessels and the piping industry
Voltage is the force that overcomes resistance to allow amperage flow
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Insufficient current to melt the wire off cleanly

13. What does voltage do in an electrical circuit?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Voltage is the force that overcomes resistance to allow amperage flow
...
The Arc voltage

14. Draw a typical volt amp curve for a machine that is designed for GMAW
3
If you dont know this check your phone
Minimum distortion due to low heat input
Cause flaking - which can clog the liner and contact tube

15. What is the key advantage of short circuiting transfer?
Reducing the gas source pressure to a constant working pressure
Minimum distortion due to low heat input
By there current carrying capacity
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

16. Why is a line heater required when using GMAW?
Constant voltage (CV)
Dry ice can form within the flow control openings and cause blockage of shielding gas
Wire feed speed
The Arc voltage

17. With straight polarity where is 2/3 of the arc energy?
Guns
Aluminum wire
3
The negative side of a welding unit

18. Why must CO2 cylinders be used in the vertical position?
Reducing the gas source pressure to a constant working pressure
To limit the short circuiting current so that spatter is reduced
To prevent drawing of liquid CO2 (Carbon Dioxide)
Shielding the molten weld metal from atmospheric contamination

19. A 10 minute cycle of welding time vs cooling time a given machine can handle.
SMAW - GTAW
Generally not as accurate
Duty cycle
Motor driven generators - Transformer rectifiers - and Inverter designs

20. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
National Electrical Manufactures Association
Flux cored wires
...
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

21. What current and polarity is generally used with GMAW?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
15 feet (4.5 meters)
DCEP (Direct Current Electrode Positive) Reverse Polarity
The negative side of a welding unit

22. In the GMAW process what does amperage control?
To prevent leakage - Carbon Dioxide (CO2)
AWS and CSA
Penetration and burn - off rate of the electrode
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

23. What is a solenoid valve and what actuates it?
Constant voltage (CV)
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
1/4 inch to 1/2 inch
Spatter problems and poor weld appearance

24. What would be an indication that the drive roll pressure is adjusted correctly?
Duty cycle
3
1/4 inch to 1/2 inch
Wire feeds smoothly (yet will slip should a problem occur in the gun)

25. List several industries that would use GMAW
Shielding the molten weld metal from atmospheric contamination
Pressure vessels and the piping industry
20 to 200 times per second
V groove or U groove

26. What is the preferred drive roll design for solid wires?
V groove or U groove
Constant voltage (CV)
Duty cycle
(DCEP) Direct Current Electrode Positive or Reverse polarity

27. What is the purpose of the shielding gas used in GMAW?
Higher 26 to 35 arc volts
Insufficient current to melt the wire off cleanly
Shielding the molten weld metal from atmospheric contamination
(DCEP) Direct Current Electrode Positive or Reverse polarity

28. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
85%
Constant current (CC)
Voltage is the force that overcomes resistance to allow amperage flow
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

29. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
20 to 200 times per second
Gives arc voltage values to the control system of the feeder
3
Penetration and burn - off rate of the electrode

30. List the factors that determine the mode of metal transfer
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Motor driven generators - Transformer rectifiers - and Inverter designs
...
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

31. What processes are constant current (CC) power sources designed to be used with?
SMAW - GTAW
Constant voltage (CV)
The Arc voltage
Insufficient current to melt the wire off cleanly

32. How are GMAW guns rated?
Reducing the gas source pressure to a constant working pressure
SMAW - GTAW
Wire feed speed
By there current carrying capacity

33. Give a description of 'pinch effect'
Cause flaking - which can clog the liner and contact tube
V groove or U groove
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
The Arc voltage

34. What is the maximum distance that hard wire can be successfully pushed?
The negative side of a welding unit
20 to 200 times per second
Penetration and burn - off rate of the electrode
15 feet (4.5 meters)

35. What output on the welding machine is used to rate the duty cycle?
Gas metal arc welding
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Minutes of elapsed time continually run (out of 10 minutes)
Cause flaking - which can clog the liner and contact tube

36. List 3 forms compressed gases may be supplied for welding
These terms are quite restrictive and often technically incorrect
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
AWS and CSA
By there current carrying capacity

37. A pull type drive system is usually used on what type of material?
20 to 200 times per second
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Motor driven generators - Transformer rectifiers - and Inverter designs
Aluminum wire

38. What controls the wire speed on a voltage sensing wire feeder?
12 to 22 arc volts
The Arc voltage
Constant current (CC)
Insufficient current to melt the wire off cleanly

39. 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
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
The negative side of a welding unit
Gives arc voltage values to the control system of the feeder

40. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
Dry ice can form within the flow control openings and cause blockage of shielding gas
Motor driven generators - Transformer rectifiers - and Inverter designs
3
Constant current (CC)

41. What does the wire feeder control?
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
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Speed of the feed motor and - starting / stopping electrode feed

42. How many times per second does short circuiting take place?
To limit the short circuiting current so that spatter is reduced
DCEP (Direct Current Electrode Positive) Reverse Polarity
1/4 inch to 1/2 inch
20 to 200 times per second

43. What is the purpose of a regulator and what does it indicate on its gauges?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Reducing the gas source pressure to a constant working pressure
DCEP (Direct Current Electrode Positive) Reverse Polarity
5.8 to 12.5 L/min

44. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
Pressure vessels and the piping industry
Guns
If you dont know this check your phone
The time rate of response for the current rise and fall

45. Why is a fiber washer required and what cylinder gas requires it?
Motor driven generators - Transformer rectifiers - and Inverter designs
The negative side of a welding unit
To prevent leakage - Carbon Dioxide (CO2)
1/4 inch to 1/2 inch

46. What is the main purpose of 'slope'?
To limit the short circuiting current so that spatter is reduced
By there current carrying capacity
When the filler wire is in direct contract with the base metal
Flux cored wires

47. What does inductance control?
V groove or U groove
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
SMAW - GTAW
The time rate of response for the current rise and fall

48. What does the term GMAW identify?
Gas metal arc welding
Minutes of elapsed time continually run (out of 10 minutes)
12 to 22 arc volts
Pressure vessels and the piping industry

49. When is the metal transferred with short circuit transfer?
Shielding the molten weld metal from atmospheric contamination
When the filler wire is in direct contract with the base metal
Speed of the feed motor and - starting / stopping electrode feed
To limit the short circuiting current so that spatter is reduced

50. List the basic equipment requirements for the GMAW process
85%
By there current carrying capacity
Constant current (CC)
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

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