Lets talk plasma and plasma tables

[jeepsr4ever]

(pt1)

Plasma

Plasma cutters work by sending an electric arc through a gas that is passing through a constricted opening. The gas can be shop air, nitrogen, argon, oxygen. etc.

This elevates the temperature of the gas to the point that it enters a 4th state of matter. We all are familiar with the first three: i.e., solid, liquid, and gas. Scientists call this additional state plasma. As the metal being cut is part of the circuit, the electrical conductivity of the plasma causes the arc to transfer to the work.

The restricted opening (nozzle) the gas passes through causes it to sqeeze by at a high speed, like air passing through a venturi in a carburetor. This high speed gas cuts through the molten metal. The gas is also directed around the perimeter of the cutting area to shield the cut

In many of today's better plasma cutters, a pilot arc between the electrode and nozzle is used to ionize the gas and initially generate the plasma prior to the arc transfer.

Other methods that have been used are touching the torch tip to the work to create a spark, and the use of a high-frequency starting circuit (like a spark plug). Neither of these latter two methods is compatible with CNC (automated) cutting.

http://www.plasma-cutter.com/plasma_process.jpg

[jeepsr4ever]

The plasma-arc process had its origin almost 50 years ago, during the height of World War II. In an effort to improve the joining of aircraft materials, a method of welding was developed that used a protective barrier of inert gas around an electric arc to protect the weld from oxidation.

Over the course of the next couple of decades, it was discovered that by restricting the opening through which the inert gas passed, the heat produced by the process was greatly increased. At the same time, the smaller opening caused the flow of gas to speed up dramatically, ultimately blowing out a channel in the work.

The plasma-arc cutting process started seeing commercial use in the first few years of the sixties. It was an extremely expensive process to undertake, and most cutting was performed by large burning services that used their systems continuously to help amortize the equipment.

In the ensuing years, various manufacturers have realized the enormous benefit even small shop owners could derive from being able to burn both ferous and non-ferrous metals. Today, dozens of manufacturers offer portable plasma cutters -- some so light they can be carried with little effort. Units are starting to appear with built-in air compressors that make the whole operation fully mobile.

Most, if not all, of the light portable plasma cutters are 110 volt machines that are suited primarily for cutting sheetmetal and other light work. The next level up are the 220 volt machines with 50 to 80 amp output current. These are portable from the standpoint that one person can put it on a truck and take it to the job.

[cheapjeep]

Damn, I understand it now :? Thanks for posting that. I want one but just can't bring myself to spend the money.

[Mudrat]

Puulllllllaaaasssssmmmaaaaaa (Homer Simpsons best voice) :lo1l:

So much fun in so little time :wink: Been using the one here are work, 1/4" plate at about an inch per second :t: :shock:

Not to be confused with Plasma Displays and monitors #-o

Mudrat

[Penguin]

Puulllllllaaaasssssmmmaaaaaa (Homer Simpsons best voice) :lo1l:

So much fun in so little time :wink: Been using the one here are work, 1/4" plate at about an inch per second :t: :shock:

Not to be confused with Plasma Displays and monitors #-o

Mudrat
Crap, no wonder my new TV wouldn't go through that chunk of steel. I wonder if the warrenty will cover it? :-|

[Goose]

We use the big plasma cutters here at work.. Man are they slick, I have cut several projects that simply would have been too time consuming in grinding and layout with standard oxy rigs or carbon arc..(although carbon arc has a cool factor with all the fireworks).

Plasma the next best thing to a lightsaber.. Now Darth hold still while I clip this gorund lead on..

[CJ Shark]

We have one of the smaller 220v lincoln plasma torches and its the best thing we ever got.

From cutting bumpers to sheet metal it works wonders.

Use a straight edge and you'll wonder why you ever used a grinder to cut metal.

[Goose]

Just an interesting little factoid I picked up the other day.. the main expense on a plasma cutter is the tip design..the company that has the patent on this tip is running out this year or next so the price on a plasma cutter should be dropping dramatically soon..

[Mudrat]

(pt1)

Plasma

Plasma cutters work by sending an electric arc through a gas that is passing through a constricted opening. The gas can be shop air, nitrogen, argon, oxygen. etc.

http://www.plasma-cutter.com/plasma_process.jpg
OK where is part 2 and 'Splain to me the 2 channels of shielding and cutting gasses. The plasma cutter I use at the shop runs off dry LP air 40-80# from a regular compressor.

Good news the price may be coming down - I want one - but don't under stand the difference between the shielding and cutting gas when it's from the same source.

Mudrat