There are low cost plasma cutters (under $500) that can cut up to about 1/2" thick...and there are more expensive industrial grade plasma cutters for cutting up to 1/2" that sell in the $1200 to $2500 range. There are air plasma 's (lowest cost, portable) and there are plasmas that can cut over 6' thick stainless steel at 1000 amps...that cost in excess of $100,000. Just like anything else there is a wide range of capability, a wide range of quality and reliability, as well as a wide price range.
The plasma torch develops an ionized gas (air in most small units) that becomes electrically conductive....the gas is forced through a nozzle orifice and DC power (similar to welding power...but typically much higher voltage) is applied to the gas stream ...this power increases the temperature of the gas stream to as much as 50,000 degrees fahrenheit. The high temperature arcs velocity increases dramatically as it passes through a small nozzle orifice...and the combined high temperature and velocity can melt any conductive material and blow it out the bottom of the cut as molten droplets.
The better plasma systems (major manufacturers, typically higher priced) do a much better job of controlling the shape of the arc and also controlling the heat in the torch and consumables...resulting in very nice cut quality at very high speeds, and with a very low operating cost (long consumable parts life). Lower cost units with lesser technology typically will be less reliable under high duty cycle usage, will use a lot of consumable parts (costly) and will provide lesser cut quality. Think about the design and physics of a plasma torch producing a 50,000 degree high velocity arc......how does it stay cool, how do the consumable last for thousands of cut cycles?
In industry, plasma is the product most often used for cutting steel, aluminum and stainless from gauge materil to about 1-1/2" thick....mechanized cutting produces amazing cut quality at speeds that are over 6 times faster than oxyfuel, and mfaster than a C02 laser on materials thicker than 3/16". Plasma , primarily due to its high cutting speed is the least costly, most productive way to cut most metals. Laser is most often used on thinner materials, water jet is slow....and used on materials or parts that cannot tolerate a heat affected zone.
The big advantage to plasma is with todays hand held plasma cutting systems.....portable devices (the Hypertherm Powermax30 as an example, is the size of a two slice electric toaster, operates off a 120 volt circuit and 4.5 cfm of regular shop compressed air.....cuts 1/4" metals with ease and can sever 1/2" steel) that have been used in place of many other metal cutting methods for about 5 decades. With the latest inverter based power supply technology...these systems can be small, reliable, and can cut with exceptional quality, ease and speed.
There.....that's why plasma can be expensive!
Jim Colt
