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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'?
Dry ice can form within the flow control openings and cause blockage of shielding gas
To limit the short circuiting current so that spatter is reduced
SMAW - GTAW
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

2. What processes are constant current (CC) power sources designed to be used with?
85%
Cause flaking - which can clog the liner and contact tube
To limit the short circuiting current so that spatter is reduced
SMAW - GTAW

3. What does the wire feeder control?
Spatter problems and poor weld appearance
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Motor driven generators - Transformer rectifiers - and Inverter designs
Speed of the feed motor and - starting / stopping electrode feed

4. What is a typical flow rate of CO2 for short circuit transfer?
5.8 to 12.5 L/min
These terms are quite restrictive and often technically incorrect
Puddle fluidity
3

5. Regulators control_____________ flowmeters SHOW____________.
Pressure - The rate of flow of a shielding gas
By there current carrying capacity
Penetration and burn - off rate of the electrode
The negative side of a welding unit

6. Why is globular transfer generally avoided with GMAW?
National Electrical Manufactures Association
To prevent leakage - Carbon Dioxide (CO2)
Spatter problems and poor weld appearance
Gas metal arc welding

7. What 2 organizations designate specifications for GMAW wires?
Aluminum wire
Minutes of elapsed time continually run (out of 10 minutes)
AWS and CSA
Insufficient current to melt the wire off cleanly

8. What happens when the electrode extension is increased?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
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
The resistace to electrical current flow increases with it. Causing the electrode to heat

9. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
20 to 200 times per second
The time rate of response for the current rise and fall
Cause flaking - which can clog the liner and contact tube
3

10. List several industries that would use GMAW
Pressure vessels and the piping industry
When the filler wire is in direct contract with the base metal
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Spatter problems and poor weld appearance

11. What is the preferred drive roll design for solid wires?
Gas metal arc welding
Penetration and burn - off rate of the electrode
V groove or U groove
The time rate of response for the current rise and fall

12. Give a brief description of the GMAW process
The Arc voltage
Controls the rate of flow of a shielding gas to the gun nozzle
Constant current (CC)
Welding process that joins metals by heating them with an electric arc

13. List the factors that determine the mode of metal transfer
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Wire feed speed
Voltage is the force that overcomes resistance to allow amperage flow
Cause flaking - which can clog the liner and contact tube

14. What type of power source is commonly used with a voltage sensing wire feeder?
Pressure - The rate of flow of a shielding gas
Guns
The negative side of a welding unit
Constant current (CC)

15. What is the effect of too much slope?
To prevent leakage - Carbon Dioxide (CO2)
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Insufficient current to melt the wire off cleanly
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

16. What is another term for electrode holders for GMAW?
Wire feed speed - Voltage control
Controls the rate of flow of a shielding gas to the gun nozzle
Guns
The Arc voltage

17. What does voltage do in an electrical circuit?
To prevent leakage - Carbon Dioxide (CO2)
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Duty cycle
Voltage is the force that overcomes resistance to allow amperage flow

18. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
5.8 to 12.5 L/min
(DCEP) Direct Current Electrode Positive or Reverse polarity
To prevent drawing of liquid CO2 (Carbon Dioxide)
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

19. What effect does increasing and decreasing the inductance have on the weld?
SMAW - GTAW
Voltage is the force that overcomes resistance to allow amperage flow
Pressure vessels and the piping industry
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

20. Give a description of 'pinch effect'
5.8 to 12.5 L/min
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
AWS and CSA

21. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Pressure - The rate of flow of a shielding gas
3
Gives arc voltage values to the control system of the feeder
...

22. List 3 wire drive systems and give a short description of each
Penetration and burn - off rate of the electrode
Shielding the molten weld metal from atmospheric contamination
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
Minimum distortion due to low heat input

23. What controls amperage when using GMAW?
National Electrical Manufactures Association
Wire feed speed
15 feet (4.5 meters)
Insufficient current to melt the wire off cleanly

24. What 2 controls are found on a GMAW set- up?
Welding process that joins metals by heating them with an electric arc
Wire feed speed - Voltage control
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Controls the rate of flow of a shielding gas to the gun nozzle

25. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
If you dont know this check your phone
Voltage is the force that overcomes resistance to allow amperage flow
Cause flaking - which can clog the liner and contact tube
Reducing the gas source pressure to a constant working pressure

26. List the basic equipment requirements for the GMAW process
The Arc voltage
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Reducing the gas source pressure to a constant working pressure
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

27. What current and polarity is generally used with GMAW?
AWS and CSA
Cause flaking - which can clog the liner and contact tube
15 feet (4.5 meters)
DCEP (Direct Current Electrode Positive) Reverse Polarity

28. What type of power source is used with a constant speed wire feeder?
Constant voltage (CV)
1/4 inch to 1/2 inch
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Gives arc voltage values to the control system of the feeder

29. Why must CO2 cylinders be used in the vertical position?
When the filler wire is in direct contract with the base metal
Spatter problems and poor weld appearance
If you dont know this check your phone
To prevent drawing of liquid CO2 (Carbon Dioxide)

30. What wire are knurled drive rolls most commonly used on?
Flux cored wires
If you dont know this check your phone
Voltage is the force that overcomes resistance to allow amperage flow
Shielding the molten weld metal from atmospheric contamination

31. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Motor driven generators - Transformer rectifiers - and Inverter designs
Voltage is the force that overcomes resistance to allow amperage flow
These terms are quite restrictive and often technically incorrect
Duty cycle

32. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Higher 26 to 35 arc volts
5.8 to 12.5 L/min
To prevent drawing of liquid CO2 (Carbon Dioxide)
Dry ice can form within the flow control openings and cause blockage of shielding gas

33. What does the term GMAW identify?
Gas metal arc welding
15 feet (4.5 meters)
Speed of the feed motor and - starting / stopping electrode feed
85%

34. With straight polarity where is 2/3 of the arc energy?
Minutes of elapsed time continually run (out of 10 minutes)
Constant- speed wire feeders and Voltage- sennsing wire feeders
The negative side of a welding unit
Gives arc voltage values to the control system of the feeder

35. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
Generally not as accurate
V groove or U groove
...
DCEP (Direct Current Electrode Positive) Reverse Polarity

36. What is the purpose of a regulator and what does it indicate on its gauges?
Guns
Reducing the gas source pressure to a constant working pressure
Short- circuiting transfer - Globular transfer - Spray transfer
Aluminum wire

37. What controls the wire speed on a voltage sensing wire feeder?
Constant voltage (CV)
The Arc voltage
1/4 inch to 1/2 inch
Flux cored wires

38. 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
Voltage is the force that overcomes resistance to allow amperage flow
Cause flaking - which can clog the liner and contact tube
Higher 26 to 35 arc volts

39. What is the recommended electrode stick- out for .035 solid wire?
DCEP (Direct Current Electrode Positive) Reverse Polarity
1/4 inch to 1/2 inch
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
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

40. What power sources are used with the GMAW Process?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Motor driven generators - Transformer rectifiers - and Inverter designs
20 to 200 times per second
Wire feed speed

41. What is the disadvantage of the gauge preset type of regulator/flowmeter?
(DCEP) Direct Current Electrode Positive or Reverse polarity
Generally not as accurate
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Minimum distortion due to low heat input

42. What are the 2 types of wire feeders available?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Cause flaking - which can clog the liner and contact tube
Wire feed speed
Constant- speed wire feeders and Voltage- sennsing wire feeders

43. In the GMAW process what does voltage control?
20 to 200 times per second
Short- circuiting transfer - Globular transfer - Spray transfer
AWS and CSA
Puddle fluidity

44. What does a flowmeter do and what does it measure?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Aluminum wire
Controls the rate of flow of a shielding gas to the gun nozzle
DCEP (Direct Current Electrode Positive) Reverse Polarity

45. A pull type drive system is usually used on what type of material?
Aluminum wire
Wire feed speed
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Dry ice can form within the flow control openings and cause blockage of shielding gas

46. List 3 forms compressed gases may be supplied for welding
Flux cored wires
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
The time rate of response for the current rise and fall
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

47. What is the key advantage of short circuiting transfer?
Minimum distortion due to low heat input
Aluminum wire
1/4 inch to 1/2 inch
V groove or U groove

48. What is a solenoid valve and what actuates it?
Guns
V groove or U groove
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

49. How are GMAW guns rated?
Guns
By there current carrying capacity
Wire feed speed
Constant current (CC)

50. Why is a line heater required when using GMAW?
Dry ice can form within the flow control openings and cause blockage of shielding gas
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Shielding the molten weld metal from atmospheric contamination
Constant- speed wire feeders and Voltage- sennsing wire feeders