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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 controls the wire speed on a voltage sensing wire feeder?
The Arc voltage
Gas metal arc welding
If you dont know this check your phone
Flux cored wires

2. What does the term GMAW identify?
These terms are quite restrictive and often technically incorrect
To limit the short circuiting current so that spatter is reduced
Minutes of elapsed time continually run (out of 10 minutes)
Gas metal arc welding

3. What is an advantage of pulsed arc transfer with GMAW?
If you dont know this check your phone
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
85%

4. What is the disadvantage of the gauge preset type of regulator/flowmeter?
SMAW - GTAW
Pressure vessels and the piping industry
Generally not as accurate
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

5. What is the effect of too much slope?
Constant voltage (CV)
Insufficient current to melt the wire off cleanly
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Constant- speed wire feeders and Voltage- sennsing wire feeders

6. What is a typical flow rate of CO2 for short circuit transfer?
Puddle fluidity
These terms are quite restrictive and often technically incorrect
5.8 to 12.5 L/min
When the filler wire is in direct contract with the base metal

7. List the three methods of metal transfer with GMAW
1/4 inch to 1/2 inch
Reducing the gas source pressure to a constant working pressure
Short- circuiting transfer - Globular transfer - Spray transfer
Duty cycle

8. What is the purpose of the shielding gas used in GMAW?
Reducing the gas source pressure to a constant working pressure
Shielding the molten weld metal from atmospheric contamination
Penetration and burn - off rate of the electrode
5.8 to 12.5 L/min

9. What current and polarity is generally used with GMAW?
By there current carrying capacity
DCEP (Direct Current Electrode Positive) Reverse Polarity
Wire feeds smoothly (yet will slip should a problem occur in the gun)
These terms are quite restrictive and often technically incorrect

10. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
Minutes of elapsed time continually run (out of 10 minutes)
Penetration and burn - off rate of the electrode
...
Short- circuiting transfer - Globular transfer - Spray transfer

11. What is the main purpose of 'slope'?
To limit the short circuiting current so that spatter is reduced
Aluminum wire
These terms are quite restrictive and often technically incorrect
Guns

12. What happens when the electrode extension is increased?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
The resistace to electrical current flow increases with it. Causing the electrode to heat
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
Welding process that joins metals by heating them with an electric arc

13. How are GMAW guns rated?
By there current carrying capacity
AWS and CSA
Dry ice can form within the flow control openings and cause blockage of shielding gas
The Arc voltage

14. What 2 controls are found on a GMAW set- up?
Reducing the gas source pressure to a constant working pressure
Wire feed speed - Voltage control
V groove or U groove
AWS and CSA

15. 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
Voltage is the force that overcomes resistance to allow amperage flow
AWS and CSA
Cause flaking - which can clog the liner and contact tube

16. With straight polarity where is 2/3 of the arc energy?
Puddle fluidity
Voltage is the force that overcomes resistance to allow amperage flow
15 feet (4.5 meters)
The negative side of a welding unit

17. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
V groove or U groove
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
National Electrical Manufactures Association
If you dont know this check your phone

18. What power sources are used with the GMAW Process?
(DCEP) Direct Current Electrode Positive or Reverse polarity
Motor driven generators - Transformer rectifiers - and Inverter designs
By there current carrying capacity
Flux cored wires

19. List the factors that determine the mode of metal transfer
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
The time rate of response for the current rise and fall
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

20. When is the metal transferred with short circuit transfer?
Controls the rate of flow of a shielding gas to the gun nozzle
Reducing the gas source pressure to a constant working pressure
When the filler wire is in direct contract with the base metal
Short- circuiting transfer - Globular transfer - Spray transfer

21. What does the wire feeder control?
Aluminum wire
Speed of the feed motor and - starting / stopping electrode feed
Duty cycle
Reducing the gas source pressure to a constant working pressure

22. What is the recommended electrode stick- out for .035 solid wire?
Aluminum wire
(DCEP) Direct Current Electrode Positive or Reverse polarity
Cause flaking - which can clog the liner and contact tube
1/4 inch to 1/2 inch

23. What is a solenoid valve and what actuates it?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Constant current (CC)
5.8 to 12.5 L/min

24. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
85%
...
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Minimum distortion due to low heat input

25. What output on the welding machine is used to rate the duty cycle?
Gas metal arc welding
Pressure - The rate of flow of a shielding gas
20 to 200 times per second
Minutes of elapsed time continually run (out of 10 minutes)

26. List the basic equipment requirements for the GMAW process
Constant current (CC)
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
3
Controls the rate of flow of a shielding gas to the gun nozzle

27. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Welding process that joins metals by heating them with an electric arc
Duty cycle
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
If you dont know this check your phone

28. What type of power source is used with a constant speed wire feeder?
Constant voltage (CV)
Gives arc voltage values to the control system of the feeder
These terms are quite restrictive and often technically incorrect
20 to 200 times per second

29. What is the required arc voltage used for short circuit transfer?
Minutes of elapsed time continually run (out of 10 minutes)
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
12 to 22 arc volts
85%

30. What is the key advantage of short circuiting transfer?
Duty cycle
Higher 26 to 35 arc volts
Minimum distortion due to low heat input
AWS and CSA

31. What 2 organizations designate specifications for GMAW wires?
Constant current (CC)
AWS and CSA
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

32. What does the abbreviation NEMA stand for?
National Electrical Manufactures Association
85%
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

33. In the GMAW process what does amperage control?
Gives arc voltage values to the control system of the feeder
Penetration and burn - off rate of the electrode
5.8 to 12.5 L/min
Gas metal arc welding

34. Why is a fiber washer required and what cylinder gas requires it?
V groove or U groove
To prevent leakage - Carbon Dioxide (CO2)
Higher 26 to 35 arc volts
Gives arc voltage values to the control system of the feeder

35. How many times per second does short circuiting take place?
Aluminum wire
12 to 22 arc volts
Gas metal arc welding
20 to 200 times per second

36. List 3 forms compressed gases may be supplied for welding
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
...
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

37. In the GMAW process what does voltage control?
Puddle fluidity
Penetration and burn - off rate of the electrode
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

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
Constant- speed wire feeders and Voltage- sennsing wire feeders
V groove or U groove
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

39. List several industries that would use GMAW
Voltage is the force that overcomes resistance to allow amperage flow
...
Pressure vessels and the piping industry
Wire feed speed

40. What does inductance control?
Duty cycle
The time rate of response for the current rise and fall
The resistace to electrical current flow increases with it. Causing the electrode to heat
SMAW - GTAW

41. A pull type drive system is usually used on what type of material?
Minimum distortion due to low heat input
12 to 22 arc volts
DCEP (Direct Current Electrode Positive) Reverse Polarity
Aluminum wire

42. What is the purpose of a regulator and what does it indicate on its gauges?
Constant current (CC)
Reducing the gas source pressure to a constant working pressure
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

43. What type of power source is commonly used with a voltage sensing wire feeder?
Reducing the gas source pressure to a constant working pressure
Constant current (CC)
(DCEP) Direct Current Electrode Positive or Reverse polarity
Pressure vessels and the piping industry

44. What is the preferred drive roll design for solid wires?
V groove or U groove
1/4 inch to 1/2 inch
Spatter problems and poor weld appearance
Flux cored wires

45. Why must CO2 cylinders be used in the vertical position?
85%
To prevent drawing of liquid CO2 (Carbon Dioxide)
Insufficient current to melt the wire off cleanly
Motor driven generators - Transformer rectifiers - and Inverter designs

46. List 3 wire drive systems and give a short description of each
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
Pressure - The rate of flow of a shielding gas
Puddle fluidity

47. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
Shielding the molten weld metal from atmospheric contamination
National Electrical Manufactures Association
Voltage is the force that overcomes resistance to allow amperage flow
3

48. Regulators control_____________ flowmeters SHOW____________.
20 to 200 times per second
Pressure - The rate of flow of a shielding gas
Constant- speed wire feeders and Voltage- sennsing wire feeders
Gas metal arc welding

49. Why is globular transfer generally avoided with GMAW?
Spatter problems and poor weld appearance
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
Aluminum wire

50. 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
Minutes of elapsed time continually run (out of 10 minutes)
3
To prevent drawing of liquid CO2 (Carbon Dioxide)