Plasma cutting is a popular cutting method used to cut metals such as steel and aluminium. To understand the process properly, we must first recognise what plasma actually is. Plasma is one of the four primary states of matter – the others are gas, liquid and solid. When a gas is ionized, plasma is formed with similar conductive properties as metal.
As a gas is heated intensely, the electrons inside separate from the nucleus and being to move around very quickly; leaving behind positively charge ions. When these ions and electrodes collide with one another they produce huge amounts of energy; giving plasma its tremendous cutting power.
How Does the Machine Work?
Firstly, pressurised gas is sent down an extremely small channel. In the centre of this channel you will find an electrode that has been negatively charged. When power is applied to this electrode and the top of the nozzle meets the material being cut, a circuit is created. This then produces a spark in the space amid the metal and the electrode. Gas travelling down the channel is heated by the spark and so it becomes plasma.
At incredibly high speed, this reaction causes a steady flow of directed plasma that can reach above 16,000 degrees Celsius. The speed and immense heat reduces the metal to molten slag. As long as the plasma remains in contact with the metal and the electrode is supplied with power, this arc cycle remains continuous; this is because the plasma itself is an electrical conductor. To ensure that this happens and to ensure the cut is protected from oxidation, the nozzle also features a second important set of channels. Supplied through these channels is a constant flow of shielding gas that is released around the cutting zone; the pressure from this gas effectively restrains the span of the plasma beam
History Behind the Machine
Plasma cutting first came into prominence in the 1960s and took inspiration from plasma welding. The process took a few years to evolve and was not used to cut sheets of metal until the 1980s. The main advantages of using a plasma cutter in those days included having no metal chips afterwards, more accurate cuts and a cleaner edge finish.
The very first plasma cutters were massive, slow and certainly not cheap! You would only usually find one on large scale production lines dealing with massive, repetitive cuts. CNC technology was applied to these machines in the early 1990s, just like many other machines of its kind. This allowed for increased flexibility and greater control.
What Does the Future Hold for Plasma Cutting?
In modern times, plasma cutters are a lot smaller and a lot cheaper too; meaning they are more available for personal projects. This means that these machines now appeal to a wider audience, not just metallurgists. Nowadays, even contemporary artists are using plasma cutters to create some unique designs and artistic pieces. The machine allows them to bore precise holes, cut any shape imaginable and perform bevel cuts too! This is just one example of how a plasma cutter can be used for personal use, rather than just being exclusive to large scale production. Who knows what else the future holds for this amazing piece of technology? What else can we achieve by harnessing the power of the fourth state of matter? Only time will tell!