OAC/PAC Flashcards
What are some advantages of PAC?
Can cut all metals that conduct electricity, faster cutting speeds, no preheating required, Heat Affected Zone is Smaller.
What are some disadvantages of PAC?
Expensive, requires electricity, compressed air or pressurized oxygen this makes it less portable.
Air is used for two purposes in PAC what are they?
Shielding Gas, & the Plasma Gas
What must be removed from the compressed air for PAC?
Moisture, Dirt, Oil, Water Vapour.
What is dross?
Residue from cutting process similar to slag.
PAC uses what polarity?
DCEN, Direct Current Electrode Negative.
Why must the pilot arc time be limited to as little as possible?
The pilot arc consumes the electrode and constricting nozzle of the Plasma Arc Cutting Torch at a higher rate than cutting.
What is the minimum required thickness of an oxygen cylinder
1/4”
What is the slot which is formed when cutting called?
Kerf
Why must you line up the at least one outside orifice with the centre orifice when OAC?
The outside orifice is a preheating orifice which brings and keeps the steel at a high enough temperature to maintain the cut.
How does the added oxygen cut the steel in OAC
As the oxygen emerges from the tip, it oxidizes the metal and blows it away to form a clean kerf.
What are some advantages of OAC over PAC?
OAC is often much more portable then PAC,
What are some disadvantages of OAC?
Cylinders are quite bulky, Can only cut ferrous metals, (metals containing significant amounts of iron) larger Heat Affected Zone, slower cutting speeds.
What happens when you use pure oxygen when PAC?
Travel speed increases, the surfaces are not contaminated with nitrogen.
What must you do to a PAC kerf that has been cut with compressed air as the gas supply before welding?
You must remove the nitriding and oxidation as these can cause porosity.
