Deck 8: Plasma Arc Cutting Equipment, Setup, and Operation

Question 1

The earliest gas tungsten arc welding process used ____.

A) tungsten
B) argon
C) oxygen
D) helium

Answer 1

D

Question 2

The plasma created by an arc ____.

A) is the fluid portion of blood
B) contains an ionized gas
C) is an ionized gas that contains both electrons and positive ions
D) cannot conduct electricity

Answer 2

C

Question 3

The voltage required for plasma arc processes range from ____ open circuit.

A) 18 to 45 volts
B) 150 to 400 volts
C) 400 to 600 volts
D) 600 to 1000 volts

Answer 3

B

Question 4

Keeping the diameter of the nozzle orifice ____ will keep the kerf ____.

A) as small as possible, smoother
B) as small as possible, smaller
C) as large as possible, smoother
D) as large as possible, smaller

Question 5

The temperature of plasma in an unrestricted arc is about ____ degrees Fahrenheit.

A) 1,000
B) 11,000
C) 43,000
D) 110,000

Question 6

Plasma cutting machines can cut mild steel ranging from _____ to _____or more in thickness.

A) 1/4 in (6 mm) to 3 in (75 mm)
B) 1/8 in (3 mm) to 1 in (25 mm)
C) 1/64 in (.4 mm) to 6 in (150 mm)
D) 1/16 in (1.6 mm) to 1.5 in (37 mm)

Question 7

The ____ is made of a special plastic that is resistant to high temperatures, ultraviolet light, and impact.

A) torch body
B) torch head
C) power switch
D) nozzle

Question 8

Why should deionized water be used for cooling high-amperage plasma torches?

A) It is free of materials that can clog the small internal openings in the torch.
B) It is free from conductive ions that can damage torch parts over time.
C) It will not freeze in cold weather.
D) Both a and b are correct.

Question 9

Some small plasma cutting machines have ______ and can be used on 120V power.

A) self-contained air compressors
B) an argon cylinder for a shielding gas
C) an oxygen cylinder for cutting gasses
D) Both b and c are correct.

Question 10

The ____ surrounding the nozzle tip is used to control the potential hazards of light, fumes, noise, and other pollutants.

A) argon
B) water
C) oxygen
D) ions

Question 11

What happens to the plasma column when water is injected around the plasma stream?

A) It concentrates the plasma stream.
B) It causes a steam cloud to shield the arc.
C) It reduces the temperature of the plasma.
D) It shorts out the plasma arc.

Question 12

What is the term used to describe the plasma cutting process that uses two different gasses?

A) Twin gas cutting
B) Multiple gas plasma cutting
C) Dual gas plasma cutting
D) Twin gas plasma cutting process

Question 13

The power switch on most handheld torches has a(n) _________ as part of the switch.

A) bright color
B) smooth finish
C) easy pull
D) safety guard

Question 14

The nozzle or gas shield of a plasma torch is made of ____.

A) tungsten or hafnium
B) copper or brass
C) chrome plated stainless steel
D) ceramic or other high-temperature resistant material

Question 15

What may need to be done as the nozzle and electrode wear?

A) Tighten the nozzle and loosen the electrode to reduce the gap.
B) Increase the cutting gas flow.
C) Increase the machine voltage.
D) Reduce the cutting speed.

Question 16

The electrode tip of a plasma torch is often made of copper with a ________ imbedded in the tip

A) tungsten
B) hafnium-coated tungsten
C) hafnium cylinder
D) All of the above

Question 17

____ are good metals to gouge because there is almost no cleanup.

A) Copper and magnesium
B) Zinc and iron
C) Stainless steel and aluminum
D) Carbon steel and copper

Question 18

Manual plasma arc cutting is ____.

A) suitable for all plasma machines
B) limited to high-power machines
C) limited to robotic processes
D) limited to low-power machines

Question 19

The ____ has a small, cone-shaped, constricting orifice in the center.

A) nozzle tip
B) nozzle insulator
C) electrode tip
D) water shroud

Question 20

What tip material is resistant to oxidation at high temperatures?

A) Tungsten
B) Hafnium
C) Copper
D) Brass

Question 21

A(n) ____________________ is used to reduce the noise level, control the plasma light, trap the sparks, eliminate most of the fume hazard, and reduce distortion.

Question 22

The metal parts of a plasma torch are usually made of ________ or ____________.

Question 23

The spacing between the electrode tip and the nozzle tip is called ____________________.

Question 24

Explain how high-frequency alternating current and a pilot arc can be used to start a plasma arc torch.

Question 25

All nontransfer-type plasma torches must have ________________.

A) argon shielding gas
B) two power cables-one for + and one for -
C) a hose to carry cooling water
D) a drag type nozzle

Question 26

Sheets can be stacked in the PAC process because PAC does not rely on the ____________________ between stacked parts.

Question 27

Explain how the gouge groove's shape can be controlled or changed in plasma arc gouging.

Question 28

Explain how metal becomes distorted during the welding process.

Question 29

What metals can produce poisonous metal fumes that must be collected in a fume collection system to prevent air pollution?

A) cadmium
B) zinc
C) chromium
D) All of the above

Question 30

____________________ is the metal compound that resolidifies and attaches itself to the bottom of a cut.

Question 31

The ____________________ distance is the distance from the nozzle tip to the work.

Question 32

Which gas produces the fastest and cleanest cuts on mild steels?

A) Compressed air
B) Oxygen
C) Argon hydrogen
D) Nitrogen

Question 33

____________________ can extend the life of the stack with up to 800 to 1500 starts.

Question 34

Describe the history of the development of plasma arc cutting.

Question 35

Any material that is ____________________ can be cut using the PAC process.

Question 36

What happens if the standoff distance is increased?

A) The arc force is increased because the resistance is higher and the voltage increases.
B) The plasma are will begin to drift sideways due to arc blow.
C) The plasma stream will lose some of its stiffness.
D) Not much happens until the distance is so great that the arc goes out.

Question 37

The nozzle is sometimes called the ____________________.

Question 38

Explain how watts are calculated.

Question 39

Why would some large plasma cutting machines have two gas hoses?

A) One is for cooling and one is for the plasma gas.
B) One is a backup in case the other is damaged by the hot sparks and slag.
C) One is for the plasma gas and one is for the shielding gas.
D) Torches only need one gas hose.

Question 40

What happens if the standoff distance becomes too close?

A) The working life of the nozzle tip is reduced.
B) The plasma stream becomes too cool to continue the cut due to the lower arc voltage.
C) As long as the arc keeps going, the cut will be better and can be cut faster.
D) On sheet metal the plate can be overheated and begin to distort from the heat.