What's the difference between a torch and a plasma cutter?
roughsawn is correct in that a plasma torch cuts metal using super-heated air (plasma) to cut through almost anything that will conduct electricity.
The advantage of a plasma torch over an oxy-acetylene torch is that the kerf of the cut is very narrow, allowing great accuracy, and the plasma is extremely hot, allowing thick material to be cut quickly with little blowout and less slag than with a conventional torch. Also, modern plasma cutting units are usually self contained with their own air compressor and filter system in the unit.
The disadvantage of plasma cutting systems, as opposed to oxy-acetylene or other fuel based type cutting systems is that you need a source of electricity and, if it's an older unit without it's own air supply, a source of clean air at a pressure of at least 30PSI (more PSI depending on thickness of material) . This isn't a problem in a shop setting, but if you are out in the field you will need some type of generator and air compressor with good filtration.
I noticed that in your post you mentioned "heating" of the metal. This really isn't feasible with a plasma torch, since the point of heat is very small. Trying to heat a metal surface, such as in a dent removal operation, will mar the surface.
"The physician can bury his mistakes, but the architect can only advise his clients to plant vines." -- Frank Lloyd Wright
Last edited by fabrk8r; 03-08-2011 at 10:04 AM.