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 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 Thickness Current Travel Speed 1/16” 35 amps 175 in/min 1/8” 40 amps 90 in/min 1/4” 40 in/min 80 amps 100 in/min 3/8” 18 in/min 55 in/min 1/2” 20 in/min 35 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

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.

OFC Equipment Combination Cutting Torch with Cutting Attachment Straight Cutting Torch

Cutting Tips 3690 Cutting Tip 3690-P Cutting Tip

OFC Cutting Tip Information

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)

Cutting Flame Types Carburizing Flame Neutral Flame Neutral Flame with Oxygen Cutting Stream Oxidizing Flame

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