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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. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Duty cycle
When the filler wire is in direct contract with the base metal
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

2. What current and polarity is generally used with GMAW?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Dry ice can form within the flow control openings and cause blockage of shielding gas
The time rate of response for the current rise and fall
Voltage is the force that overcomes resistance to allow amperage flow

3. With straight polarity where is 2/3 of the arc energy?
Spatter problems and poor weld appearance
The negative side of a welding unit
20 to 200 times per second
1/4 inch to 1/2 inch

4. What is a typical flow rate of CO2 for short circuit transfer?
Minimum distortion due to low heat input
5.8 to 12.5 L/min
Gas metal arc welding
The Arc voltage

5. List the three methods of metal transfer with GMAW
Guns
Pressure - The rate of flow of a shielding gas
Short- circuiting transfer - Globular transfer - Spray transfer
15 feet (4.5 meters)

6. What type of power source is commonly used with a voltage sensing wire feeder?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Minutes of elapsed time continually run (out of 10 minutes)
Constant current (CC)
3

7. Why is a line heater required when using GMAW?
Cause flaking - which can clog the liner and contact tube
Dry ice can form within the flow control openings and cause blockage of shielding gas
Shielding the molten weld metal from atmospheric contamination
Penetration and burn - off rate of the electrode

8. What is the purpose of the shielding gas used in GMAW?
V groove or U groove
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Shielding the molten weld metal from atmospheric contamination
12 to 22 arc volts

9. Give a description of 'pinch effect'
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
15 feet (4.5 meters)
To prevent leakage - Carbon Dioxide (CO2)
By there current carrying capacity

10. 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
Speed of the feed motor and - starting / stopping electrode feed
Minimum distortion due to low heat input
Welding process that joins metals by heating them with an electric arc

11. What does inductance control?
The time rate of response for the current rise and fall
By there current carrying capacity
To prevent leakage - Carbon Dioxide (CO2)
Pressure - The rate of flow of a shielding gas

12. What power sources are used with the GMAW Process?
15 feet (4.5 meters)
Duty cycle
Aluminum wire
Motor driven generators - Transformer rectifiers - and Inverter designs

13. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
Wire feeds smoothly (yet will slip should a problem occur in the gun)
V groove or U groove
3
National Electrical Manufactures Association

14. How are GMAW guns rated?
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
By there current carrying capacity
3

15. What is a solenoid valve and what actuates it?
Puddle fluidity
1/4 inch to 1/2 inch
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

16. Why is a fiber washer required and what cylinder gas requires it?
20 to 200 times per second
To prevent leakage - Carbon Dioxide (CO2)
By there current carrying capacity
Constant current (CC)

17. What 2 controls are found on a GMAW set- up?
Wire feed speed - Voltage control
Minutes of elapsed time continually run (out of 10 minutes)
Constant- speed wire feeders and Voltage- sennsing wire feeders
The time rate of response for the current rise and fall

18. What is the required arc voltage used for short circuit transfer?
15 feet (4.5 meters)
1/4 inch to 1/2 inch
The Arc voltage
12 to 22 arc volts

19. What wire are knurled drive rolls most commonly used on?
Higher 26 to 35 arc volts
Cause flaking - which can clog the liner and contact tube
...
Flux cored wires

20. What type of power source is used with a constant speed wire feeder?
The Arc voltage
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
Constant voltage (CV)
By there current carrying capacity

21. What is the key advantage of short circuiting transfer?
Minimum distortion due to low heat input
...
Higher 26 to 35 arc volts
The resistace to electrical current flow increases with it. Causing the electrode to heat

22. What is the effect of too much slope?
The resistace to electrical current flow increases with it. Causing the electrode to heat
Insufficient current to melt the wire off cleanly
1/4 inch to 1/2 inch
Minimum distortion due to low heat input

23. What is the preferred drive roll design for solid wires?
Duty cycle
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
To limit the short circuiting current so that spatter is reduced
V groove or U groove

24. How many times per second does short circuiting take place?
The negative side of a welding unit
Constant current (CC)
Voltage is the force that overcomes resistance to allow amperage flow
20 to 200 times per second

25. List the basic equipment requirements for the GMAW process
Shielding the molten weld metal from atmospheric contamination
Minutes of elapsed time continually run (out of 10 minutes)
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Short- circuiting transfer - Globular transfer - Spray transfer

26. A pull type drive system is usually used on what type of material?
Puddle fluidity
Welding process that joins metals by heating them with an electric arc
85%
Aluminum wire

27. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Generally not as accurate
Minimum distortion due to low heat input
12 to 22 arc volts
When the filler wire is in direct contract with the base metal

28. What are the 2 types of wire feeders available?
When the filler wire is in direct contract with the base metal
Insufficient current to melt the wire off cleanly
Constant- speed wire feeders and Voltage- sennsing wire feeders
National Electrical Manufactures Association

29. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
15 feet (4.5 meters)
Cause flaking - which can clog the liner and contact tube
Gives arc voltage values to the control system of the feeder
Generally not as accurate

30. List the factors that determine the mode of metal transfer
20 to 200 times per second
These terms are quite restrictive and often technically incorrect
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Speed of the feed motor and - starting / stopping electrode feed

31. In the GMAW process what does amperage control?
When the filler wire is in direct contract with the base metal
Penetration and burn - off rate of the electrode
Duty cycle
The time rate of response for the current rise and fall

32. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Gives arc voltage values to the control system of the feeder
Constant- speed wire feeders and Voltage- sennsing wire feeders
Constant voltage (CV)
...

33. 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
V groove or U groove
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Pressure - The rate of flow of a shielding gas

34. Why is globular transfer generally avoided with GMAW?
3
Dry ice can form within the flow control openings and cause blockage of shielding gas
Spatter problems and poor weld appearance
Minutes of elapsed time continually run (out of 10 minutes)

35. What controls the wire speed on a voltage sensing wire feeder?
1/4 inch to 1/2 inch
The Arc voltage
Generally not as accurate
Minutes of elapsed time continually run (out of 10 minutes)

36. What is the maximum distance that hard wire can be successfully pushed?
Minutes of elapsed time continually run (out of 10 minutes)
15 feet (4.5 meters)
Constant- speed wire feeders and Voltage- sennsing wire feeders
The Arc voltage

37. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
...
These terms are quite restrictive and often technically incorrect
Reducing the gas source pressure to a constant working pressure
85%

38. In the GMAW process what does voltage control?
Gives arc voltage values to the control system of the feeder
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
Puddle fluidity

39. What is the recommended electrode stick- out for .035 solid wire?
1/4 inch to 1/2 inch
Pressure - The rate of flow of a shielding gas
Welding process that joins metals by heating them with an electric arc
Generally not as accurate

40. What controls amperage when using GMAW?
The Arc voltage
These terms are quite restrictive and often technically incorrect
Wire feed speed
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

41. What does the abbreviation NEMA stand for?
National Electrical Manufactures Association
The time rate of response for the current rise and fall
AWS and CSA
Constant current (CC)

42. What does the wire feeder control?
Speed of the feed motor and - starting / stopping electrode feed
To limit the short circuiting current so that spatter is reduced
Reducing the gas source pressure to a constant working pressure
Insufficient current to melt the wire off cleanly

43. What does the term GMAW identify?
Gas metal arc welding
National Electrical Manufactures Association
The time rate of response for the current rise and fall
Pressure - The rate of flow of a shielding gas

44. What processes are constant current (CC) power sources designed to be used with?
SMAW - GTAW
Voltage is the force that overcomes resistance to allow amperage flow
Dry ice can form within the flow control openings and cause blockage of shielding gas
Shielding the molten weld metal from atmospheric contamination

45. What is an advantage of pulsed arc transfer with GMAW?
Insufficient current to melt the wire off cleanly
Gives arc voltage values to the control system of the feeder
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
If you dont know this check your phone

46. 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
Controls the rate of flow of a shielding gas to the gun nozzle
These terms are quite restrictive and often technically incorrect

47. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
85%
Controls the rate of flow of a shielding gas to the gun nozzle
Puddle fluidity
Wire feeds smoothly (yet will slip should a problem occur in the gun)

48. Why must CO2 cylinders be used in the vertical position?
Cause flaking - which can clog the liner and contact tube
To prevent drawing of liquid CO2 (Carbon Dioxide)
V groove or U groove
Minimum distortion due to low heat input

49. What is another term for electrode holders for GMAW?
Shielding the molten weld metal from atmospheric contamination
The negative side of a welding unit
Guns
AWS and CSA

50. What happens when the electrode extension is increased?
The resistace to electrical current flow increases with it. Causing the electrode to heat
Duty cycle
The negative side of a welding unit
Reducing the gas source pressure to a constant working pressure