Presentation on theme: "Metal Cutting Plasma Oxy Fuel. Plasma Arc Cutting (PAC) is a cutting process that uses an arc and a high-velocity, ionized gas coming through a nozzle."— Presentation transcript:
Plasma Arc Cutting (PAC) is a cutting process that uses an arc and a high-velocity, ionized gas coming through a nozzle to cut all metals that can not be cut with flame Such as: Stainless steel Aluminum Copper
PAC Plasma is a super heated gas that is ionized. Ionized- Electrons in the gas have broken away form their atoms and will conduct electricity. Gases used for plasma cutting includes: Hydrogen Argon Nitrogen and mixture,plus air and oxygen
PAC How it cuts ◦ The plasma gas (compressed air) is forced through a nozzle and heated by the arc which reaches to 5,0000 °F
Advantages of PAC Can cut all metals Fast cutting speeds Little distortion from heat No hazardous gases Oxygen based system do not leave nitride deposits Nitrogen based systems are for aluminum, stainless steel and nickel
Disadvantages Plasma Torch is expensive Not portable (needs electricity) Metal fumes created can be a health hazard Puts tremendous heat into the metal around the cut Creates HAZ Hardens materials next to the cut
Safety/ Maintenance A minimum of a #9 filter shield should be used Need proper ventilation to remove harmful gases Dip electrode into anti-spatter compound Do not allow Pilot Arc to continue for long periods of time
Setting the PAC Torch If torch amps is set too high travel speed needs to be increased ThicknessCurrentTravel Speed 1/16”35 amps175 in/min 1/8”40 amps90 in/min 1/4”40 amps40 in/min 1/4”80 amps100 in/min 3/8”40 amps18 in/min 3/8”80 amps55 in/min 1/2”40 amps20 in/min 1/2”80 amps35 in/min
How to Use Clean metal Hook up ground cable Draw cutting pattern on metal Hold torch 1/16-1/8” from metal (torch stand will help maintain this) Hold torch at a 70 to 90 ° angle Pull button when arc begins pull torch across metal
Cutting Speed Too Slow- Molten metal will collect on bottom of work piece and need to be ground off (this is called Dross) Too Fast- Metal will not be cut all the way through
Oxy-Fuel Cutting, Welding Definition: Burning is the rapid oxidation of a material Does Metal Burn? ◦ Virtually all materials will burn if they are first heated to their ignition temperature. ◦ Steel ignition temp is when it is cherry red, 1300-1400 ° C ◦ Oxygen burns preheated metal and blows it away from the work piece.
Oxyacetylene welding (OAW) Oxygen and acetylene gas are mixed in the torch tip. The mixture burns at the torch tip. The heat from this flame is used to melt the base metal and welding rod. This melted material forms a weld joint.
Oxy-Fuel Cutting Set-up Oxy-Fuel Cutting Set-up All set up the same as oxy-fuel welding except: ◦ To set working pressure for oxygen must open cutting valve
Oxy-Fuel Cutting Process Clean metal Draw line Make jig to keep cut straight Hold tip 1/16-1/8” above metal Preheat metal to cherry red color Open oxygen valve and push torch through metal ◦ (Angle tip slightly toward direction of cut)
Advantages Can cut complex shape Can cut carbon and low carbon steel Inexpensive process Can have multiple cutting torch Disadvantages It is slower than other cutting systems Cut accuracy is not as good as plasma, water jet,laser Creates heat affected zone