How Plasma Cutter technology works

This section gives some background on Plasma and its use

We've included a bit about the physics and the design of the cutters themselves.
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The properties of Plasma

Most people recognise the three common states of matter, solid, liquid and gas, but there is a fourth state called plasma. The matter in the universe contains a huge proportion of plasma but we don't see it here because of its very high temperatures, for instance the Sun is mainly plasma.

Naturally, on Earth, we do see it in lightning, which of course carries a huge amount of energy.

How does it form ? In physical terms, as you put more energy into each state of matter, the molecules speed up, which is what causes solids to melt into liquids and liquids to evaporate to gas. However, if gas is super-heated, electrons break free and start to collide, releasing massive amounts of energy.

This energy is what is used in a controlled way in a plasma cutter and also in flourescent lights and neons.

Temperatures in cutter arcs reach around 25,000 degrees centrigrade, which is what gives plasma cutters their ability to cut thick metal easily.

Design of Plasma Cutters

These work by sending a pressurized gas through a constricted opening equipped with an electrode at its centre. Power is applied to the electrode and a powerful spark is generated to start the process (there are different spark methods used). This spark heats the gas into its plasma state, creating the arc, which is also conductive, forming a circuit with the metal being cut.

As long as power is applied and the circuit is maintained, the cutting arc is continuously applied to the metal surface for cutting, in whatever direction you choose.

In practice, a free arc would be out of control in its direction, so the cutter nozzle is surrounded by a set of gas channels which release shielding gas. The gas pressure controls the plasma arc stability, direction and radius.

Starting the arc

Many plasma cutters form the initial spark when the nozzle is touched onto the metal to be cut. There are also those with an initial internal pilot arc which transfers to the work when touched, or those with a high frequency start circuit (effectively a spark plug type function).