2 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 flameSuch as:Stainless steelAluminumCopper
3 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:HydrogenArgonNitrogen and mixture ,plus air and oxygen
4 PACHow it cutsThe plasma gas (compressed air) is forced through a nozzle and heated by the arc which reaches to 5,0000°F
5 Advantages of PAC Can cut all metals Fast cutting speeds Little distortion from heatNo hazardous gasesOxygen based system do not leave nitride depositsNitrogen based systems are for aluminum, stainless steel and nickel
6 Disadvantages Plasma Torch is expensive Not portable (needs electricity)Metal fumes created can be a health hazardPuts tremendous heat into the metal around the cutCreates HAZHardens materials next to the cut
7 Safety/ Maintenance A minimum of a #9 filter shield should be used Need proper ventilation to remove harmful gasesDip electrode into anti-spatter compoundDo not allow Pilot Arc to continue for long periods of time
8 Setting the PAC Torch If torch amps is set too high travel speed needs to be increased ThicknessCurrentTravel Speed1/16”35 amps175 in/min1/8”40 amps90 in/min1/4”40 in/min80 amps100 in/min3/8”18 in/min55 in/min1/2”20 in/min35 in/min
9 How to Use Clean metal Hook up ground cable Draw cutting pattern on metalHold torch 1/16-1/8” from metal (torch stand will help maintain this)Hold torch at a 70 to 90° anglePull button when arc begins pull torch across metal
10 Cutting SpeedToo 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
12 Oxy-Fuel Cutting, Welding Definition:Burning is the rapid oxidation of a materialDoes 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, ° COxygen burns preheated metal and blows it away from the work piece.
13 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.
17 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
18 Oxy-Fuel Cutting Process Clean metalDraw lineMake jig to keep cut straightHold tip 1/16-1/8” above metalPreheat metal to cherry red colorOpen oxygen valve and push torch through metal(Angle tip slightly toward direction of cut)
20 AdvantagesCan cut complex shapeCan cut carbon and low carbon steelInexpensive processCan have multiple cutting torchDisadvantagesIt is slower than other cutting systemsCut accuracy is not as good as plasma, water jet ,laserCreates heat affected zone