Posts Tagged ‘Plasma Arc Cutter’

The Plasma Cutting Process : PAC

Monday, October 3rd, 2011

Plasma Arc Cutting (PAC) is probably one of the single most coveted items in a well equipped shop. Almost all commercial shops are equipped with Oxy-fuel for cutting. In fact, I can’t think of any reason a commercial shop would not have a Oxy-Acetylene rig. But up until the last 10 years, many established shops did not have a plasma cutter. A few still don’t. As technology has improved, and prices have gone down and availability has gone up, more and more shops and even hobbyists are making the plasma plunge.

What makes plasma so desirable? It would be difficult to pinpoint any one feature. Plasma cutters are capable of making extremely clean and accurate in any metal, something that cannot be done with Oxy-Acetylene torches. Speed is another factor, with plasma having an edge over Oxy-Acetylene when trying to achieve similar cut quality. Low temperature input also reduces metal distortion while cutting. A major deciding factor for most is the relatively low skill required to operate one. Almost anyone can turn out competent cuts within a short amount of time with just a little practice. Most plasma cutters are easily taken right to the site to work. There’s no dangerous gases to work with. There’s no large bottles to carry around or fill. Most plasma cutters use air compressors which are already found in many shops. Air hoses can be run quite a long ways to the unit giving a lot more portability around the shop with a reduced foot print. Some plasma cutters even have the compressor built in and will operate on 120 volts, allowing it to be used almost anywhere in or out of the shop.

There are some drawbacks to plasma though. While plasma may give Oxy-Fuel a run for its money on performance cutting, it cannot be used in situations where it is necessary to heat metal. Nor can it weld or braze. Plasma can only be used to cut or gouge any metal. Oxy/Acetyelene will weld, cut, braze and heat…though it is limited mostly to steel on cutting. The initial purchase of a plasma system is much higher as well, especially if an air compressor is needed. Consumables should always be kept handy as this is a wear item that is constantly needed. Also, electricity is needed and may be a limiting factor in remote locations. Oxy-Fuel rigs have no such requirements. Torch tips for Oxy-Fuel last much longer for sure and rarely need replacing.

Carefully evaluate your needs and capabilities before purchasing a plasma cutter. It is not a good fit for everyone. It is not a substitute for a good Oxy-Fuel rig because of its limitations. But if you do feel it’s a good fit for you, Everlast offers a full range of plasma cutters from 50 to 100 amps, with cutting capacities up to nearly 2 inches. Well priced from $700 dollars, there’s probably a unit that will fit your needs.

Share

Operating Procedures of Plasma Arc Cutter

Wednesday, December 16th, 2009
  1. To start the plasma arc cutter make sure the air pressure is an adequately around 70 p.s.i. for most plasma arc cutter units and the ground clamp is attached
    to the work piece.
  2. Turn the plasma arc cutter on and regulate the amperage the manufacturers specifications for the thickness of metal to be cut.
  3. Position the defensive cup over the metal, press the igniter button and permit the arc to become established. Next, move the arc over the cut line and create the cut.
  4. The thicker the metal the slower the travel speed must be to get a good cut and vice versa. The quality of the cut generally decreases as the metal thickness increases and the travel speed decreases.
  5. A guide bar may be used to help to get good straight cuts.
  6. The shielding cup and contracting nozzle should be held approximately 1/8″ to 1/4″ above the metal being cut. The operator should avoid dragging the contracting nozzle and shielding cup on the metal when making the cut except they are specifically designed to touch the base metal while cutting.
  7. Always make cuts on the waste side of the cut line.
  8. Avoid cutting with the plasma arc cutter in damp or wet locations. The hazards of electrical stock really increased.
  9. If plasma arc cutting over an open drum with a grate be aware that the fume plume will be directed back toward the operator. Avoid this condition if at all possible, otherwise limit the exposure to fumes to short duration’s.
  10. Cuts with the plasma arc cutter may be made by moving forward, backward, or sideways. Establish which direction is easiest for you and use that process as often as possible.
  11. Always shift the plasma arc cutter as fast as possible when making a cut. This increases time efficiency, improves the cut quality, and reduces the build up of dross.
  12. Compressed air used in plasma arc cutter should be dry or the cutter will not give way to a quality cut or it not cut at all. An auxiliary air filter may be place in the compressed air line to condition the air for a plasma arc cutter.
  13. Always turn the plasma arc cutter off before resting the torch down and leaving the work area.
  14. If the quality of the cut deteriorates to an intolerable level either the constricting nozzle, the electrode, or both may need to be changed. The electrode on most plasma arc cutter will have a life of about twice the life of the constraint nozzle. Keep a supply of constricting nozzles and electrodes on hand as they deteriorate quickly during continuous use. Turn the plasma arc cutter off to put on replacement parts. Keep the plasma arc cutter torch leads and ground lead stored so they will not be cut or damaged when not in use.
Share