FreeWeldingForum.com 
Welding Forum Community presented by LONGEVITY
877 - Long - Inc | 877.566.4462
Results 1 to 10 of 10

Thread: Plasma cutting gasses

  1. #1

    Plasma cutting gasses

    i am with sic on this Nitrogen makes a Clean cut on certian materials We use it at work with the plasmas

    Here is a lil info
    Air is the most versatile plasma gas; it produces good cut quality and speed on mild steel, stainless, and aluminum. Air also lowers the cost of operation because it is not necessary to purchase gases. (For this reason air plasma systems are not popular with gas suppliers.) However air is not free. Shop air must be cleaned to remove contamination such as particulate, oil mist, and moisture. The best solution for air plasma systems is a good-sized, dedicated air compressor, a refrigerated dryer, and a bank of filters to take out particulate, oil mist, and any remaining moisture. Another concern with air plasma is weldability of the cut edge. Some nitriding and oxidation of the cut surface occurs with air plasma; this can cause porosity in welds. The problem is usually corrected by simply using good quality weld wire with denitriders and deoxidizers. For versatility, good speed, low dross levels, and parts life up to 600 starts, air is a good option for many shops. Air shield gas is the best choice when using air plasma.

    Oxygen has become the industry standard for cutting Carbon Steel because it provides the best cut quality and fastest cutting speed of any plasma gas. Steels (Cutting stainless or aluminum with oxygen plasma gas is not recommended.) Oxygen plasma gas reacts with carbon steel to produce a finer spray of molten metal, each droplet having a lower surface tension. This molten spray is more easily ejected from the kerf. The disadvantage of oxygen is the cost of the gas and the consumable parts life. However state-of-the-art oxygen plasma systems use inert starting gases (such as nitrogen) with oxygen plasma to achieve similar parts life to nitrogen or air systems. These systems may have parts life in the 800-1500-start range. Increased consumable and gas costs are usually offset by a decrease in expensive secondary operations to remove dross and straighten beveled parts. Air shield is typically used with oxygen plasma.

    Nitrogen was used in most early plasma torches. It is still the best choice if you cut a lot of aluminum and stainless. The cut quality and parts life is excellent. (Over 1000 starts is normal) However, on thick materials (usually over "), at the high end of your plasma system's capability, switch to Argon-Hydrogen. Generally air is the best secondary when using nitrogen plasma. CO2 works well-slightly improving surface finish, cutting speed, and parts life over air. But CO2 costs more than air and requires multiple manifolded gas cylinders or a bulk system to deliver adequate flow. Water is a good secondary to use with nitrogen plasma if the system allows. It makes a very smooth shiny cut surface on stainless and aluminum. Water secondary must be used with a water table.

    Argon Hydrogen is the gas of choice for thick stainless and aluminum cutting (>1/2") The mixture typically used is 35% Hydrogen: 65% Argon (H-35). Argon hydrogen is the hottest burning plasma gas and provides the maximum cutting capability. (Argon hydrogen is used in water injection torches up to 1000 amps for cutting up to 6" stainless.) In multi-gas torches, Argon hydrogen provides a straight cut and a very smooth almost polished surface on stainless steel. Some jagged dross may occur along the bottom edge. Nitrogen is typically used as the shield gas with argon hydrogen. The disadvantage of this combination is its expense.

    so with all that

    For mild steel use oxygen plasma and air shield for the best cut quality, lowest dross levels, minimal rework, excellent weldability and highest cutting speed/productivity.

    For best cut quality on stainless and aluminum under " use nitrogen plasma and air secondary for a good balance of cut quality and affordability. For a slightly better and faster cut, use CO2 as the secondary. If your system allows, water shield will provide the best edge quality.

    For best cut quality on thick stainless and aluminum use Argon-Hydrogen with Nitrogen secondary. WARNING! Your system must be equipped for safe operation with argon hydrogen gas.

    For most economical cutting, clean dry shop air is the best choice for mild steel, stainless, and aluminum.

    ---------- Post added at 02:47 AM ---------- Previous post was at 02:29 AM ----------

    Quote Originally Posted by LONGEVITY View Post
    No,

    The plasma cutter will work only of the air compressor. The argon is used for Tig, but the lp-50d is a stand alone plasma cutter.

    Thanks
    I am assuming the Torches you use are single supply inlet so you cant run multiple gas shielding
    Last edited by Gadget; 02-10-2011 at 09:19 AM.
    Ahp 200x tig acdc
    forcecut 42i
    Miller xmt350
    Lincoln LN-25
    Victor oxy/acetylene/
    Bunch of tools of the trade to much to list
    http://instagram.com/weldor_wes/

  2. #2
    I moved this post so it could be made sticky. Thank you for this very informative information Welding Wookie.
    Units owned Longevity PROmts 200

    Force Cut LP80 plasma cutter
    Longevity auto dark welding helmet

    Atlas 10x36" lathe
    Craftsman 5HP 30 Gal compressor
    Home made CNC router/plasma/hot wire foam cutting, 3D printing table powered by Longevity Force Cut LP80
    Home built aluminum foundry, HF 4x6 bandsaw

  3. #3
    thanks, wookie.... and yes, the longevity torches are single supply inlet..
    Torchmate 5 x 10 custom built CNC table
    6 (each) Thermadyne 252i mig/ stick/ tig
    Thermal Dynamics a-60 automated cutter
    Thermal cutmaster 52 handheld cutter
    '07 pro300 miller
    '08 275 trailblazer miller
    '99 250 trailblazer
    12vs extreme suitcase feeder
    2 (each) xr-a 50 foot push-pull feeders (for aluminum mig)
    800 ton break
    400 ton shear
    MM350p
    xmt 304
    (do i REALLY need to keep going?)

    nothing fancy, just a few hot glue guns for metal

    www.sicfabrications.com

  4. #4
    Plasma cutting is a process that is used to cut steel and other metals of different thicknesses (or sometimes other materials) using a plasma torch. In this process, an inert gas (in some units, compressed air) is blown at high speed out of a nozzle; at the same time an electrical arc is formed through that gas from the nozzle to the surface being cut, turning some of that gas to plasma. The plasma is sufficiently hot to melt the metal being cut and moves sufficiently fast to blow molten metal away from the cut

  5. #5
    Hi Fruehauf and welcome to the forum. We like pictures here so be sure to include some showing your work. Be sure to post a bit about yourself in the introduce yourself section so we can get to know you. Also, keep an eye out for the next contest here. The odds of winning a great new Longevity machine are very good.
    Dan
    Units owned Longevity PROmts 200

    Force Cut LP80 plasma cutter
    Longevity auto dark welding helmet

    Atlas 10x36" lathe
    Craftsman 5HP 30 Gal compressor
    Home made CNC router/plasma/hot wire foam cutting, 3D printing table powered by Longevity Force Cut LP80
    Home built aluminum foundry, HF 4x6 bandsaw

  6. #6

    Cool Many thanks -

    Excellent article - slowly gaining knowledge on my own time and really appreciate the efforts on material such as this. Deebs

  7. #7
    Hi Deebs and welcome to the forum. When you get a chance, please post a bit about yourself in the introduce yourself section so we can get to know you.
    Dan
    Units owned Longevity PROmts 200

    Force Cut LP80 plasma cutter
    Longevity auto dark welding helmet

    Atlas 10x36" lathe
    Craftsman 5HP 30 Gal compressor
    Home made CNC router/plasma/hot wire foam cutting, 3D printing table powered by Longevity Force Cut LP80
    Home built aluminum foundry, HF 4x6 bandsaw

  8. #8
    Member
    Join Date
    Mar 2014
    Location
    Coimbatore,Tamil Nadu
    Posts
    90
    Many fabricators choose plasma systems with "dual-gas" or "multi-gas" capability,Air is the most versatile plasma gas; it produces good cut quality and speed on mild steel, stainless, and aluminum,Oxygen has become the industry standard for cutting Carbon Steel,nitrogen was used in most early plasma torches,argon hydrogen is the gas of choice for thick stainless and aluminum cutting

  9. #9
    Moderator KHK's Avatar
    Join Date
    Oct 2008
    Location
    Chicago suburbs
    Posts
    2,702
    Good info Thanks!
    keith
    The older the Boys, the more expensive the TOYS
    Previously Owned equipment;
    lot's
    Current equipment;
    3HP Speedair air compressor, Wilton drill press, Craftsman 10x36 lathe, 10 ton hydrolic press, Portaband band saw, OA torch, Small home brew CNC machine, powered by my 200PI
    2 Longevity autodarking helmets
    160d MIG
    WeldAll 200PI

  10. #10
    Hey Keith, long time no see. Good to have you back.
    Dan
    Units owned Longevity PROmts 200

    Force Cut LP80 plasma cutter
    Longevity auto dark welding helmet

    Atlas 10x36" lathe
    Craftsman 5HP 30 Gal compressor
    Home made CNC router/plasma/hot wire foam cutting, 3D printing table powered by Longevity Force Cut LP80
    Home built aluminum foundry, HF 4x6 bandsaw

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •