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  • A technical question

    Hi:

    After reading some Wikipedia article about plasma cutters, there is something in my mind which don't fit right and it just keep bothering me.
    How come the torch's Tip doesn't melt away if it serves as the outlet for the 16000 °C plasma flame?

    Please help.

  • #2
    Because "flame" is generated eternal to tip and being pushed away from tip, not being generated in the tip... And it not a flame but a jet of super heated gas...

    Dale
    "Fear The Government That Wants To Take Your Guns" - Thomas Jefferson..

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    • #3
      Welcome to the forum.
      Lincoln A/C 225
      Everlast PA 200

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      • #4
        Same as oxy-acetylene, the actual jet and maximum heat is external, but improper standoff can tear up the consumables. As a beginner, the "guides" are worthwhile. Freehand is for TV stars.
        Blacksmith
        Stickmate LX AC/DC
        Big cheap (Chinese) Anvil
        Hand cranked coal forge
        Freon bottle propane forge
        HH 210 and bottle of C25

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        • #5
          Left out of the above is cooling and speed of the plasma. The plasma is traveling close to the speed of sound and the torch is cooled by gas or water, and the plasma jet does not actually contact the hafnium insert.

          BTW, plasma is not just "superheated gas", but, is a fourth state of matter (solid,liquid, gas, and plasma), and the most abundant state in the universe. And the process is actually closer to TIG welding, which also uses gas and water cooling to prevent the electrode from melting away from the plasma heat (all arcs are plasma). The OA process is a chemical reaction.

          Here is a better source than Wikipedia:

          http://www.twi-global.com/technical-...derations-051/
          Last edited by Northweldor; 04-03-2015, 07:53 AM.

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          • #6
            Copper melts at a bit over 1000 degrees F, the plasma arc that is shaped by the nozzle orifice is somewhere between 24,000 degrees F and 50,000 degrees F.

            The actual reason the nozzle orifice does not instantly melt has to do with the design and engineering that goes into the gas flow (or air flow in an air plasma torch) inside the torch.

            All plasma cutting torches today have a method of swirling the gas inside the torch, with the original reason for swirl being the ability to control cut edge angularity better than with the earliest torches (late 1950's through early 1960's) which use a laminar or straight gas flow. In the last 20 years plasma process engineers have developed swirl patterns in better technology torches that actually use the centrifugal properties of the gas swirl to sling cooler, heavier particles of the ionized gas to the outside of the plasma plenum (inside the torch). These cooler gas particles are un-ionized (non conductive) and are cooler than the melting temperature of the copper nozzle.....and tend to create a boundary layer of cool gas that insulates the nozzle bore from the hot plasma stream that is forced down through the center of the nozzle orifice. Further, surface resistance of the nozzle bore helps to slow this boundary layer of cool gas down, maintaining and increasing the cooling effect.

            In order to make the above technology work.....excellent design of the torch is necessary, and, accurate control of the gas pressure, gas flow and swirl rate are absolutely necessary. Newer, better technology plasma systems from the major suppliers provide dramatically longer consumable parts life as compared to older plasmas, or most of the low cost imports that are not well engineered.

            So....when you have one of the good quality plasma systems that takes advantage of the better torch technology...be sure to use the correct consumables as manufactured by the designers of the torch, and be sure to follow cutting specs listed in the manufacturers operators manual in terms of gas flow or pressure, cut height, cut speed, amperage...and make sure you have the correct set of consumables in the torch for what you are cutting. Changing anything with the process will upset the delicate balance of gas swirl in the torch, and can cause even the best torch to provide short consumable parts life.

            Jim Colt Hypertherm

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            • #7
              I have the same question, thanks for the answer

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              • #8
                A technical que

                If you have any technical issues, feel free to submit a post. We would be more than glad to answer any and all of your technical questions.

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