When cutting metal, a plasma cutter is one of the best tools to use because it is simple and efficient. Large amounts of research and technology have been put into plasma cutters and as a results they are easy to use and cut almost as precisely as a laser.
Do not confuse a plasma cutter with a welding torch. A welding torch uses a flame created from burning a certain gas, like oxyacetylene. On the other hand, a plasma cutter creates plasma (the fourth state of matter) to cut metal. The idea of plasma is simple enough and I believe before you can use a plasma cutter properly you have to know how plasma cutters work. When you ionize and heat an inert gas (Argon) or oxygen/nitrogen (air) to temperatures around 15,000 degrees Celsius it becomes plasma. Plasma is difficult to visualize and explain. Basically, it is a substance that is a gas and a liquid at the same time. Plasma can be used to cut through metal without having any affect on the metal adjacent to the cut, so it cuts very cleanly.
Creating the plasma in the nozzle of the plasma cutter is an interesting process. Inside the nozzle there is a negative electrode. The metal that you will be cutting is turned into the positive electrode by clamping a cable from the plasma cutting machine onto the metal. The inert gas is forced passed the negative electrode, where it is ionized, and then out through the nozzle at very high speeds. When the end of the nozzle is touched to the metal (completing the circuit) a spark fires up through the nozzle to the negative electrode (this is also known as an “arc”). The spark is what heats the rushing, ionized gas to 15,000 degrees Celsius creating plasma. The plasma streams out of the tiny hole in the nozzle and sears through the metal making a cut.
In the past, plasma cutters were imprecise because the flow of plasma out of the nozzle was not focused. Advances in technology have changed that. Today, plasma cutters are much neater and do not require as much power to function.
You can buy used plasma cutters online for around $1,000. For example, the Hobart AirForce 250ci for cutting and piercing retails for $1,035.00. A great use of plasma cutters is body panel work on cars. A car’s metal is relatively thin and body panels are usually not that big so they are easy to work with. Unfortunately, the cars of today have a lot of plastic panels which are not the ideal candidates for plasma cutting.
Understanding how plasma cutters work goes a long way towards protecting yourself. It is important to remember that plasma cutters can be dangerous machines when they are not used properly, so make sure you know a bit about plasma cutter safety