Chapter 11 Plasma Cutting
_______ is the most efficient orifice gas for PAC.
Shop air
True or false? A properly made cut on thin base metal produces a kerf width that is two times the diameter of the hole in the constricting nozzle
True
True or false? An inverter creates a square-wave alternating current
True
True or false? For manual cutting, the torch should be brought 1/16"-1/8" (1.5mm-3mm) from the work before the switch is pressed to start the cut.
True
True or false? For plasma arc cutting with up to 300 amperes, a welding helmet with filter plate of number 9 should be worn
True
True or false? Free electrons in plasma conduct electricity.
True
True or false? Oxygen can be used to cut carbon steel
True
True or false? Plasma arc gouging removes only a portion of the thickness of the base metal
True
True or false? Plasma arc welding power supplies are constant current machines
True
True or false? The minimum number lens that should be worn during plasma arc cutting is #9.
True
True or false? The pilot arc is located between the electrode and the constricting nozzle
True
True or false? The transferred arc is between the electrode and the base metal
True
True or False? There should be a short period of shielding gas preflow when air is used as the cutting gas.
false
True or false? A transferred arc erodes both the electrode and the constricting nozzle
false
True or false? The most commonly used orifice gas for manual plasma arc cutting is nitrogen
false
True or false? The polarity of the electrode in plasma arc cutting is positive
false
Which of the following is used as an electrode material?
hafnium
The term dual flow plasma arc cutting refers to PAC that uses _______.
A plasma and shielding gas
True or false? If the proper current setting is unknown, it is better to set the current a little lower than needed prior to cutting.
False
True or false? Metal being blown through the kerf that exits the bottom surface and creates a trail of molten metal indicates a travel speed that is too slow.
False
For plasma arc cutting, the torch is held ________ above the work.
1/8"- ¼" (3mm-6mm)
The purpose of the high velocity gas in the PAC process is to _______.
Blow the molten metal through the base metal
Which of the following is not a shielding gas used for plasma arc gouging?
Carbon dioxide
Metal that is removed during a cut but becomes attached to the metal surface is referred to as _____.
Dross
Which of the following is not a shielding gas for plasma arc gouging.
Hydrogen
When H-35 is used as an orifice for cutting stainless steel, the shielding gas is _____.
Nitrogen
Which statement about gases used in PAC is false?
Oxygen is used to cut stainless steel
Match the labels for the parts of the plasma arc cutting torch with the names of the parts.
b electrode d heat shield a torch body c constricting nozzle e swirl ring
The purpose of the _____ is to ionize orifice gas.
pilot arc
True or False? The term dual-flow plasma arc cutting refers to the use of two different orifice gases in the PAC process.
true
True or false? If gas from a shop manifold is used, a hose is connected from the regulator on the manifold to the power source
true
